Article

Effects of palatability and learned satiety on energy density influences on breakfast intake in humans

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Abstract

The present report explored firstly how palatability modified the effects of energy density (ED) on short-term food intake and changes in rated appetite within a single test meal, and secondly how repeated consumption altered these relationships. Experiment 1 contrasted disguised high (HED) and low (LED) versions of a food presented in bland and palatable forms. Mass consumed varied as an interaction of palatability and ED, with subjects eating least of the bland/HED version, suggesting some un-learned satiating effects. No such compensation for ED was seen in the palatable/HED condition, and overall energy intake increased with ED. Palatability had the expected stimulatory effect on appetite, but rated hunger decreased more rapidly as a function of energy consumed in the HED conditions. Experiment 2 introduced novel distinctive flavours to examine whether repeated experience of palatable HED and LED versions resulted in learned satiety. Participants ate the same mass of LED and HED versions on first exposure, but after two training days with each food, where they consumed a fixed amount, they subsequently ate a greater mass of the LED version, consistent with learned satiety. Increased intake was accompanied by a slower rate of decline in hunger in the LED condition. Despite these changes, energy intake remained higher with the HED version. Liking for the LED version was greater than the HED version at the end, possibly due to mild aversive qualities of eating a fixed portion of the HED food during training. Together these data suggest that energy density is the major determinant of short-term energy intake in the absence of orosensory cues predictive of energy differences, but that learning of flavour-energy associations can, to some extent, allow short-term energy consumption to be regulated.

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... This would suggest that individuals had learnt that less of the flavour associated with the high energy content needed to be consumed in order to achieve satiation than of the flavour paired with the low energy content. Evidence of FNL-S was later replicated by Booth, Mather & Fuller (1982), Gibson & Booth (2000), Yeomans, Weinberg, & James (2005) and more recently Yeomans, McCrickerd, Brunstrom, & Chambers (2014). However, a larger number of studies have failed to replicate this association between orosensory properties of food and satiety (e.g., Specter et al., 1998;Zandstra, Syubenitsky, De Graaf, & Mela, 2002;;Hogenkamp et al., 2010, Zeinstra et al., 2009). ...
... One explanation put forward to specifically explain the difficulty in observing FNL-S may be that both FNL-H and FNL-S are both expressions of the same learning mechanism, which may not be identifiable given previous study designs (Yeomans, 2012). This concept is demonstrated in a study by Yeomans, Weinberg, & James (2005) who found that individuals consumed more of a food previously associated with a flavour signalling low-energy content, which is consistent with FNL-S but there was also an increase in liking for the low-energy version of the food. It is therefore difficult to disentangle whether changes in intake reflected an increased desire to consume the low energy dense version or learning that more of the flavour paired with the low-energy needed to be consumed in order to achieve satiation. ...
... Conversely, if an expectation is low from the outset then this may limit the extent to which it can reduce still further (a floor effect). However, it is also possible that individuals who felt fuller than initially expected may have selected smaller ideal portion sizes because they experienced sensations of oversatiation, which has been identified as a potential confound in previous studies of FNL (Yeomans, Weinberg, & James, 2005;). This does however seem unlikely in the current study as individuals provided ratings of aversive feelings for three hours after eating, with no significant differences in ratings of discomfort, nausea, bloatedness, or sluggishness observed across the three unanticipated fullness groups. ...
Thesis
Various physiological and psychological factors are thought to be important in determining energy intake and meal control. This thesis focuses on two such factors: dietary learning and individual differences in interoception (the ability to detect internal bodily signals). Chapters 4 and 5, focus primarily on flavour-nutrient learning, which refers to instances where associations develop between a foods orosensory properties (e.g., flavour, texture) and the post-ingestive consequences of consumption (e.g., satiety, pleasure). Some weak evidence was observed for this form of learning, with individuals believing a flavour was more rewarding if it had previously been paired with a high rather than low-energy dairy breakfast. These studies also revealed that individuals may form dietary associations where they experience a sense of surprise satiety after eating. Specifically, individuals who felt fuller than they had initially anticipated, showed a large change in how filling they expected the food to be in the future. This ‘surprise satiety’ finding is exciting as the concept of surprise does not appear to have been applied to dietary learning before. The second theme of research focused on the role individual differences in interoception (the ability to detect internal bodily signals) may have upon different dietary behaviours (chapters 5-9). This revealed little evidence to suggest that interoceptive variability might influence: dietary learning (chapter 5), decisions individuals make about portion size (chapter 6), whether the negative effects of consuming large meals on post-prandial cognitive function are anticipated (chapter 7), the propensity to exhibit different eating traits (external, emotional and restrained eating) (chapter 8), and whether having a strong sense of internal bodily signals and being able to form a clear memory for foods eaten combine, to reduce later intake and attentional biases towards foods (chapter 9). In conclusion, unanticipated fullness appears to be an exciting prospect for future research in human dietary learning. In contrast, there was little evidence to suggest that individual variation in interoception might influence eating behaviours.
... A more recent study found evidence suggestive of such learning for intake of a breakfast food: Yeomans et al. (2005b) compared ad libitum consumption of high and low energy versions of porridge before and after two training experiences of fixed intake of these versions with distinct arbitrary flavors. On the first occasion, participants ate the same weight of both versions on average. ...
... Since eating is habitual, the amount eaten (and associated sensorimotor cues) is usually an approximate (and learned) predictor of energy intake, on which, in the novel context of a laboratory study, participants may be happy to rely. So energy intake will follow disguised manipulations of energy density, as is found (Yeomans et al., 2005b). Gibson and Booth (2000) argued that it is more meaningful to explain this as "active" regulation of amount eaten, through learning, rather than "passive" overconsumption of energy (e.g., Blundell et al., 1995). ...
... This idea is now more widely accepted, even if the mechanisms have not been fully appreciated (Stubbs and Whybrow, 2004). Of course, sensory and nutritional properties of the foods, and genetic and psychological characteristics of the eaters, will add variability to this regulation (De Castro, 2001;Westerterp-Plantenga, 2004;Yeomans et al., 2005b). ...
Chapter
Learning underlies the development and regulation of habitual eating, including our likes and dislikes, choosing foods most appropriate to our current motivational state, and controlling how much is eaten. In young children, mere exposure to the flavor of a food increases acceptance of that food. Similarly, exposure to flavors in amniotic fluid and breast milk might link maternal dietary choice with preference development in children. Children's preferences are strongly correlated with the energy density of foods because of the reinforcing effects of energy eaten when hungry, that is, flavor consequence learning. Carbohydrate, fat, and protein have all proved effective in reinforcing flavor preferences. Flavors associated with higher energy consumption are preferred when hungry, but conversely less liked when full than lower energy-paired flavors, and they suppress subsequent intake. Sensitivity to post-ingestive energy differences may weaken with age and externalization of eating control. Frequent eating of high fat energy-dense foods may impair neural inhibition of learned appetite, creating a vicious circle leading to obesity. Flavor-flavor learning occurs when a neutral flavor is eaten together with a flavor that already has strong positive or, more robustly, aversive properties. This could form a shortcut for transferring important information from one sensory property to another. The necessity for explicit awareness of flavor-consequence or flavor-flavor associations for learned control of eating is discussed. This is important because it has implications as to who should be held accountable for eating behavior, and so for public health strategies to control obesity and dietary-related disease.
... 104 This hypothalamic system of orexigenic and anorexigenic neuropeptides is modulated by a complex coordination of gastrointestinal hormones that act either on the promotion of food intake or on the promotion of satiety and food intake inhibition (Table 1). 5,6,9,17,18,31,36,37,[42][43][44]66,68,69,77,93,95,97,103,105,106 Other food-intake regulators What determines food intake is not as straightforward as being hungry and seeking food. Numerous factors, internal and external, can directly affect ingestive behavior. ...
... A lower Satiety Quotient is also associated with food cravings that could result in binge-eating episodes and overconsumption of food. 105,172 Using a VAS, it is possible to calculate the Satiety Index, determined by the area under the curve of subjective satiety or fullness ratings after the ingestion of a specific type of food, and comparing this with the area under the curve obtained from reference foods. 173 The Satiety Index correlates directly with the nutritional composition of foods, being higher in foods with higher protein and fiber content. ...
Article
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Satiety is a complex state, influenced by numerous factors that go beyond food ingestion. Satiety influences food habits and behavior, thus affecting human health. This review provides an overview of physiological mechanisms involved in satiety and of methodologies to assess food intake and satiety in both animal models and humans. The following topics are highlighted: differences between satiety and satiation; how the central nervous system regulates food intake and satiety; the impact of different macronutrients on satiety; and how the manipulation of food composition might influence overall satiety. Bringing together knowledge on this myriad of satiety mechanisms and how we can study them is useful to better understand and control obesity and other eating disorders.
... It has been proposed that this is a part of the food control system that ensures adequate amounts of the macronutrients (fat, carbohydrate, and protein) are ingested to meet nutritional needs. It might seem that measuring hunger or satiety levels might be a way to predict food intake but this has met with varying levels of success (Yeomans, 1998;Yeomans, Weinberg, & James, 2005) and this topic is excluded from this review due to a lack of consensus. Emotional factors (e.g., stress and mood) and their relationship to food intake have been studied on Earth and the underlying principles have been reviewed (Canetti, Bachar, & Berry, 2002;Piqueras-Fiszman & Jaeger, 2014). ...
... Trials with the general population to study the link between food sensory properties and food intake have also been carried out (Forde, 2018;Sorensen, Moller, Flint, Martens, & Raben, 2003;Yeomans, 1998;Yeomans et al., 2005;Yin, Hewson, Linforth, Taylor, & Fisk, 2017;Zandstra, De Graaf, Mela, & Van Staveren, 2000). There is a general trend of food acceptability driving intake, although, as in the military studies, other factors seem to be involved. ...
Article
Full-text available
The intention to send a crewed mission to Mars involves a huge amount of planning to ensure a safe and successful mission. Providing adequate amounts of food for the crew is a major task, but 20 years of feeding astronauts on the International Space Station (ISS) have resulted in a good knowledge base. A crucial observation from the ISS is that astronauts typically consume only 80% of their daily calorie requirements when in space. This is despite daily exercise regimes that keep energy usage at very similar levels to those found on Earth. This calorie deficit seems to have little effect on astronauts who spend up to 12 months on the ISS, but given that a mission to Mars would take 30 to 36 months to complete, there is concern that a calorie deficit over this period may lead to adverse effects in crew members. The key question is why astronauts undereat when they have a supply of food designed to fully deliver their nutritional needs. This review focuses on evidence from astronauts that foods taste different in space, compared to on Earth. The underlying hypothesis is that conditions in space may change the perceived flavor of the food, and this flavor change may, in turn, lead to underconsumption by astronauts. The key areas investigated in this review for their potential impact on food intake are the effects of food shelf life, physiological changes, noise, air and water quality on the perception of food flavor, as well as the link between food flavor and food intake.
... It has been proposed that this is a part of the food control system that ensures adequate amounts of the macronutrients (fat, carbohydrate, and protein) are ingested to meet nutritional needs. It might seem that measuring hunger or satiety levels might be a way to predict food intake but this has met with varying levels of success (Yeomans, 1998;Yeomans, Weinberg, & James, 2005) and this topic is excluded from this review due to a lack of consensus. Emotional factors (e.g., stress and mood) and their relationship to food intake have been studied on Earth and the underlying principles have been reviewed (Canetti, Bachar, & Berry, 2002;Piqueras-Fiszman & Jaeger, 2014). ...
... Trials with the general population to study the link between food sensory properties and food intake have also been carried out (Forde, 2018;Sorensen, Moller, Flint, Martens, & Raben, 2003;Yeomans, 1998;Yeomans et al., 2005;Yin, Hewson, Linforth, Taylor, & Fisk, 2017;Zandstra, De Graaf, Mela, & Van Staveren, 2000). There is a general trend of food acceptability driving intake, although, as in the military studies, other factors seem to be involved. ...
Article
Andrew Taylor, Jonathan Beauchamp, Loic Briand, Victor Demaria Pesce, Martina Heer, Thomas Hummel, Scott McGrane, Christian Margot, Serge Pieters, Paola Pittia and Charles Spence consider the role of food flavour in combatting under-consumption of nutrients by astronauts on the Mars expedition.
... food intake or loss of compliance (15)(16)(17). Findings from previous research are mixed: one 84 study indicated possible increased compensatory intake after repeated consumption of LED 85 foods (18), another did not (19). 86 SW has been shown to be broadly comparable to similar commercial and slightly better than 87 non-commercial programs for weight loss (20). ...
... Although not demonstrated in the time frame used in this study, it is possible that after 466 following an LED diet for a sustained period, individuals learn to associate the sensory 467 properties of LED meals with low energy and compensate by increasing portion size or 468 seeking higher energy dense foods (17,18). Thus, it would be useful to repeat this study and Analyses controlled for method of assessing body composition (BodPod or bioelectrical impedance). ...
Article
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Background: Low energy density foods (LED) reduce energy intake (EI); whether this effect is sustained over time and during weight loss is unknown. Objective: This trial examined the effects of LED compared to high energy density (HED) meals on appetite, EI and control over eating in the laboratory and during a weight management program that encourages unrestricted intake of LED foods [Slimming World, UK (SW)] compared to a self-led Standard Care program [NHS weight loss plan (SC)]. Methods: Overweight and obese women (n=96;age:41.03±12.61 years; BMI:34.00±3.61 kg/m2) were recruited from SW- or SC-program. Primary outcomes included appetite, food preferences (liking and wanting for LED and HED foods), cravings and evening meal EI (LED, HED) in response to calorie-matched LED (≤0.8 kcal/g) and HED (≥2.5 kcal/g) breakfast and lunch meals. Probe day tests were conducted at weeks 3 and 4 and repeated at weeks 12 and 13 in a within-day cross-over design. Secondary outcomes including body weight and program experience were measured from week 1 to 14 in a parallel-group design. Dietary compliance was monitored using weighed food diaries at weeks 3 and 12. Results: Intention-to-treat (ITT) and completers-analyses showed SW lost more weight compared to SC [ITT:-5.9% (95%CI:-4.7, -7.2) versus -3.5% (-2.3,-4.8), p<0.05; completers:-6.2% (-4.8,-7.6) versus 3.9% (-2.5,-5.2), p<0.05]. SW reported greater control over eating and more motivation to continue the program compared to SC. LED meals increased sensations of fullness and reduced hunger on probe days (p<0.001). Total-day-EI was 1057±73 kcal less (95% CI:912, 1203;36%) under LED compared to HED (p<.001). Liking for LED and HED foods and wanting for HED foods were lower pre-lunch under LED compared to HED conditions and liking decreased to a greater extent after the LED-lunch. SW reported fewer cravings under LED compared to HED conditions (p<0.05). On probe days, appetite and EI outcomes did not differ between weeks 3 and 12 or SW- and SC-groups. Conclusion: LED meals improve appetite control in women attempting weight loss and the effect is sustainable. Consumption of LED meals likely contributed to weight loss in the SW-program.ClinicalTrials.gov #NCT02012426.
... As well as evidence of a change in flavour pleasantness, participants increased their intake of breakfast only in the Unlabelled HE condition. This finding is in line with other studies of human FNL, where increased liking has been shown alongside increased intake (Yeomans, Gould, Mobini, & Prescott, 2008;Yeomans et al., 2009;Yeomans, Leitch, Gould, & Mobini, 2008;Yeomans, Weinberg, & James, 2005). Thus, the simplest explanation for this finding is that increased liking enhanced intake, given the well-documented effects of palatability as a driver of intake (Yeomans, Blundell, & Lesham, 2004). ...
... Those ideas might have suggested that participants would learn that the HE breakfast was more filling, and the LE less so, and altered their intake in order to optimise the effects on ingestion (perhaps increasing intake of the LE version which might have been perceived as inadequately filling, and decreasing intake of the HE version if it was perceived as too filling). Since the only change in intake was an increase in the Unlabelled HE condition, this implies that these breakfasts were not so large that they generated the unpleasant post-ingestive effects shown in other studies to reduce liking and mealsize (Yeomans et al., 2009;Yeomans, Weinberg, & James, 2005), and so liking and consequent intake increased. ...
Article
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Associations between flavours and the consequences of ingestion can lead to changes in flavour liking depending on nutrient content, an example of flavour-nutrient learning. Expectations about the consequences of ingestion can be modified by information at the point of ingestion, such as nutritional labelling. What is unknown is the extent to which these label-based expectations modify flavour-nutrient learning. Since nutrient information can alter expectations about how filling a product would be, we hypothesised that labels predicting higher energy (HE) content would enhance satiety and so promote more rapid flavour learning. To test this, participants consumed either a lower (LE: 164kcal) or HE (330kcal) yoghurt breakfast on four separate days, either with no product label or with labels displaying either the actual energy content (Congruent label) or inaccurate energy (Incongruent label). Participants rated liking on all four days: on days one and four they could also consume as much as they liked, but consumed a fixed amount (300g) on days two and three. Both liking and intake increased with exposure in the HE, and decreased in the LE, condition when unlabelled in line with flavour-nutrient learning. In contrast, no significant changes were seen in either the Congruent or Incongruent label conditions. Contrary to predictions, these data suggest that flavour-nutrient learning occurs when there is an absence of explicit expectations of actual nutrient content, with both accurate and inaccurate information on nutrient content disrupting learning.
... However, after the second exposure to isocaloric preloads, no difference in meal intakes was observed between the 2 preloads, which suggested that the caloric adjustment may have been be adapted to the effective ED of the preload after 2 exposures. In adults, it has been shown that the liking for a new flavor increased after only 1 or 2 exposures (23,24), whereas in children, the number of exposures ranged from 6 to 8 (13,14,20,25). To our knowledge, the effect of a lower number of exposures on liking has never been tested in children. ...
... This result is consistent with previous studies conducted in children, which showed that caloric adjustment was improved after 2 or 3 exposures to an unfamiliar food (19,20,22). In adults, it has previously been shown that flavor-nutrient hedonic learning may occur after only 1 or 2 exposures (23,24). However, this null finding may have also been related to a lack of power of the current design to reveal it. ...
... One of the key mechanisms responsible for the promotion of energy intake and encouraging food ingestion is taste. Promotion of food intake occurs due to the palatability of food (Yeomans et al. 2005) and the sensitivity of the mouth in relaying the attributes of the palatable food. Palatability increases appetite and therefore food consumption, whereas satiety limits consumption by reducing meal size or by delaying the time of the next meal (Drewnowski 1998). ...
... Short-term intake of foods (i.e. snacking) due to palatability is associated with high fat, high energy dense foods which are consumed out-with mealtimes resulting in satiety responses being overridden (Yeomans et al. 2005). In this instance cessation is strongly affected by sensory-specific satiety, the intake of a single food relative to the intake of other foods. ...
... However, after the second exposure to isocaloric preloads, no difference in meal intakes was observed between the 2 preloads, which suggested that the caloric adjustment may have been be adapted to the effective ED of the preload after 2 exposures. In adults, it has been shown that the liking for a new flavor increased after only 1 or 2 exposures (23,24), whereas in children, the number of exposures ranged from 6 to 8 (13,14,20,25). To our knowledge, the effect of a lower number of exposures on liking has never been tested in children. ...
... This result is consistent with previous studies conducted in children, which showed that caloric adjustment was improved after 2 or 3 exposures to an unfamiliar food (19,20,22). In adults, it has previously been shown that flavor-nutrient hedonic learning may occur after only 1 or 2 exposures (23,24). However, this null finding may have also been related to a lack of power of the current design to reveal it. ...
Article
Background: The contribution of sweet beverages to weight gain in children is controversial; the impact of these beverages on caloric adjustment needs clarification. Objective: We studied the influence of energy-density (ED) conditioning on the liking for sweet beverages and caloric adjustment after their consumption in children. Design: We used a within-subject design. Forty-four 8-11-y-old children were exposed to the following 2 distinctly flavored, sweetened beverages: a high-energy (HE) version (150 kcal) and a no-energy (NE) version (0 kcal). During a 4-wk initial conditioning period, children were exposed either 2 or 7 times to each beverage. After a 3-wk stability period (without exposure), children were exposed 3 times to both beverages with a reversed association between the ED and flavor (4-wk reversed-conditioning period). Flavor liking and food intake during meals after the consumption of each beverage were assessed before and after each period. Results: After the initial conditioning, the liking for both beverages increased (P < 0.001). After the stability period, the liking for the HE flavor was higher than for the NE flavor (P = 0.024). After the reversed conditioning, the liking for the flavor initially paired with the HE beverage tended to remain higher than for the NE flavor (P = 0.089). Initially, energy intakes during the meal did not differ after the consumption of NE or HE beverages. After the initial conditioning and up until the end of the reversed conditioning, energy intakes were lower after the HE beverage than after the NE beverage regardless of the beverage flavor (eg, after reversal; caloric compensation score: 29%). The number of exposures did not influence liking or energy intake. Conclusion: After the association between a flavor and ED and reversal of this association, liking may be first guided by ED and then the flavor firstly associated with ED, whereas the partial caloric compensation may consistently be guided by ED. This trial was registered at clinicaltrials.gov as NCT02070185.
... However, other researchers have been unable to replicate these results with humans. For example, after repeated exposure to flavour-cued high-and low-energy porridge, at subsequent ad libitum breakfasts a significantly greater portion (measured by weight) of the low-energy porridge was consumed, in comparison to the high-energy version (Yeomans, Weinberg, & James, 2005). These findings indicate learned satiety to a certain extent, but total energy intake was still greater for the high-than for the low-energy version of the porridge. ...
... It was expected that learned satiety may manifest in these experiments as changes to hunger ratings over the course of the exposures, which would indicate a learned association between the sensory aspects of the food and the satiating effect of consumption (e.g. Yeomans, Weinberg, et al., 2005) -in essence revealing anticipated satiety -but no such evidence was generated. ...
Thesis
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Sensory-specific satiety (SSS) is a significantly greater pleasantness decline for a consumed (Eaten) food, than foods that are tasted but not consumed (Uneaten). SSS occurs during consumption, reaches optimal magnitude immediately afterwards, and returns to baseline within two to three hours. The phenomenon is dependent on the sensory properties, rather than the energy or macronutrient content of the food. To the extent that an Uneaten food shares similar sensory properties with the Eaten food, the Uneaten food may be subject to pleasantness decline: a transfer effect. Repeated exposure to a food stimulus may alter liking in the long-term, through mere exposure, monotony, and dietary learning paradigms resulting in an association between the novel target food and either a known food stimulus, or a consequence of consumption. Novel foods are more susceptible to these effects than familiar foods, for which learned associations may have already formed. Repeated consumption alone does not modulate SSS, but to date such studies have not tested novel foods. Through six experiments this research explores the influences of long-term pleasantness changes of novel foods and the number and type of Uneaten foods present during SSS testing, on the magnitude of SSS for snack foods. While no evidence of mere exposure or dietary learning was found, and in some instances experiments failed to induce SSS, these negative results are likely due to methodological, and sometimes procedural issues in the design and conduct of experimental testing. Findings revealed SSS to be vulnerable to a number of procedural and methodological factors, such as: portion size; baseline novelty and pleasantness ratings; hunger; perceived ambiguity of measurement scales; and expectations raised by the type and number of Uneaten foods present during testing
... These variables were also observed together by the General Appetite Score (GAS). The score was adapted, since, in this case, it only has three variables, satiation, hunger, and desire to eat, and was calculated as follows: GAS = [satiation + (100-hunger) + (100-desire to eat)] /3, where 100 indicates more appetite and 0 indicates less appetite [18][19][20]. ...
Article
To evaluate the effect of the consumption of jucara and açai beverages on appetite. A randomized pilot double-blind and crossover study was conducted with sixteen healthy adults who were submitted to two trials, a beverage with acai or jucara.
... As ΔSatiety increased, consumer liking of the attributes decreased, while satiety before and after positively affected consumer liking. However, Yeomans et al. [131] suggested that flavor and palatability of porridges may be a better predictor of the intent to purchase of a product than perceived satiety. Further research into perceived satiety over the course of product evaluation may be necessary. ...
Article
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This study was conducted to evaluate three different food products containing cricket powder for consumer acceptability, emotional response, satiety, and plate waste. US untrained consumers (n = 108), from the San Luis Obispo, CA area, were recruited to evaluate three food products (sausage, pasta, and brownies) as components in a three-course meal that either contain cricket powder (CP) or not (Control). The CP sausage was found to have lower liking scores than the Control for the attributes tested (p < 0.05). The CP pasta was found to be higher in overall liking than the Control (p < 0.05). The CP Brownies were rated highly across the attributes, except for texture and aftertaste (p < 0.05). Though the CP products were found to be as acceptable as the Controls, the use of cricket powder may have affected the texture and flavor profile of both the CP sausage and brownies. The participants selected more positive emotions terms for both the CP and Control products than negative emotions. Negative terms selected, such as worried, decreased once the products were consumed (p < 0.05). Plate waste and subjective satiety may also be indicators of consumer acceptability. Significant correlations were found between appearance liking and satiety as well as taste liking and plate waste for both the Control and CP products/dishes (p < 0.05). Based on this work, future acceptance of insect-based products may be encouraged by evaluating the products throughout an eating experience.
... >10 total exposure days) (15)(16)(17). Compensation in these various studies represents an "unlearned" response to the satiating effect of calories (single or first exposure) (9,18) as well as a potentially learned response (repeated exposure) (9,(18)(19)(20)(21). ...
Article
Full-text available
Background A possible driver of obesity is insensitivity (passive overconsumption) to food energy density (ED, kcal/g); however, it is unclear whether this insensitivity applies to all meals. Objectives We assessed the influence of ED on energy intake (kcal) across a broad and continuous range of energy densities comprised of non-covertly manipulated, real-world meals. We also allowed for the possibility that the association between energy intake and ED is non-linear. Methods We completed a secondary analysis of 1,519 meals which occurred in a controlled environment as part of a study conducted by Hall and colleagues to assess the effects of food ultra-processing on energy intake. To establish the generalizability of the findings, the analyses were repeated in 32,162 meals collected from free-living humans using data from the UK National Diet and Nutrition Survey (NDNS). Segmented regressions were performed to establish ED ‘breakpoints’ at which the association between consumed meal ED and mean centered meal caloric intake (kcal) changed. Results Significant breakpoints were found in both the Hall dataset (1.41 kcal/g), and the NDNS dataset (1.75 and 2.94 kcal/g). Centered meal caloric intake did not increase linearly with consumed meal ED, and this pattern was captured by a two-component (‘volume’ and ‘calorie content’ (biologically derived from the sensing of fat, carbohydrate, and protein)) model of physical meal size (g), in which volume is the dominant signal with lower energy-dense foods and calorie content is the dominant signal with higher energy-dense foods. Conclusions These analyses reveal that, on some level, humans are sensitive to the energy content of meals and adjust meal size to minimize the acute aversive effects of overconsumption. Future research should consider the relative importance of volume and calorie content signals, and how individual differences impact everyday dietary behavior and energy balance.
... The pleasantness rating of the CSþ flavor increased after training with the small portion meals while the CSÀ rating remained unchanged. However, with the large portion meals, the rating of the CSÀ flavor increased while that of the CSþ flavor decreased after training, confirming earlier findings (Yeomans et al., 2005b). These studies indicated that flavor preference conditioning varied with the amount of energy consumed. ...
Chapter
Synopsis Although responses of humans and laboratory rodents to food and fluid flavors include some innate tendencies, many of their flavor preferences and aversions are learned by association with other flavors, or with postoral consequences of ingestion. This chapter reviews flavor-flavor and flavor-consequence learning, explaining the methods of study and differences in potency of postoral agents of conditioned aversion/avoidance and preference.
... This is often calculated through the equation: satiety + fullness + (100 − hunger) + (100 − prospective food consumption)/4. This approach also allows the satiety quotient relative to the energy/ weight content of the food provided to be calculated [18][19][20], allowing assessment of subjective appetite relative to amount of energy consumed. The use of this approach has allowed the identification of distinctive satiety phenotypes. ...
Article
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Purpose of Review The goals of this paper are to report current research practices in investigations of human appetite control and to assess their relationships with emerging theoretical principles. Appetite is often distinguished by the separation of homeostatic and hedonic processes. Recent Findings This report assesses the validity of a homeostatic toolkit to measure subjectively perceived hunger and its relationship to the developing processes of satiation (control of meal size) and satiety (control of the post-eating period). The capacity of a procedure to measure the influence of hedonic processes on food intake is also evaluated. A major issue is the relationship between the pattern of eating behaviour (influenced by the underlying drive to eat and the inhibition induced by the act of eating itself) and the parallel underlying profile of hormonal and other metabolic biomarkers. Summary Increasing recognition is being given to individual variability in the expression of appetite, and the fact that the use of the average (mean) response conceals important information about the nature of appetite control. There is a growing interest in the identification of satiety phenotypes that operate in parallel to metabolic phenotypes. Interestingly, energy expenditure (metabolic and behavioural) contributes to an energy balance framework for understanding energy intake (appetite).
... This is just an exercise." Amounts plated rather than consumption were measured in order to eliminate the effects of palatability and post-ingestive experiences on portion size selection during the subsequent visit [28,29]. Participants indicated if they drank diet or regular soda. ...
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This study examined the effects of one night of sleep curtailment on hunger, food cravings, food reward, and portion size selection. Women who reported habitually sleeping 7–9 h per night, were aged 18–55, were not obese, and had no sleep disorders were recruited. Sleep conditions in this randomized crossover study consisted of a normal night (NN) and a curtailed night (CN) where time in bed was reduced by 33%. Hunger, tiredness, sleep quality, sleepiness, and food cravings were measured. A progressive ratio task using chocolates assessed the food reward. Participants selected portions of various foods that reflected how much they wanted to eat at that time. The sleep duration was measured using a single-channel electroencephalograph. Twenty-four participants completed the study. The total sleep time was shorter during the CN (p < 0.001). Participants reported increased hunger (p = 0.013), tiredness (p < 0.001), sleepiness (p < 0.001), and food cravings (p = 0.002) after the CN. More chocolate was consumed after the CN (p = 0.004). Larger portion sizes selected after the CN resulted in increased energy plated for lunch (p = 0.034). In conclusion, the present study observed increased hunger, food cravings, food reward, and portion sizes of food after a night of modest sleep curtailment. These maladaptive responses could lead to higher energy intake and, ultimately, weight gain.
... The breakfast with enriched biscuits + enriched juice was evaluated the most unpleasant of the test breakfasts. Highly palatable foods have been found to be less satiating, as indicated by increased intake in a meal (Yeomans, Weinberg, & James, 2005). It is controversial whether lower palatability of food increases only satiation (occurring during the meal) or also satiety ( de Graaf, De Jong, & Lambers, 1999;Yeomans, Lee, Gray, & French, 2001;Sorensen, Moller, Flint, Martens, & Raben, 2003). ...
Thesis
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The current study explored the impact of cereal food structure on digestion and satiety. Food structure is important for acceptability, functionality and health effects. Cereal foods contribute significantly to energy and nutrient intakes in the diets worldwide. The benefits of consuming a diet rich in whole grain and dietary fibre (DF) are evident, and cereal DF complex is most likely behind the beneficial effects. The first part of the study investigated the effect of bread structure on mastication-induced structure disintegration, starch hydrolysis and dissolution of compounds from bread matrices. Despite the structural differences among the studied rye and wheat breads, there were only small differences in mastication processes. However, rye breads disintegrated to smaller particles than wheat bread and starch tended to hydrolyse at a slower rate by salivary α-amylase. A large array of compounds was dissolved from masticated breads to saliva. Specifically, peptides and amino acids were dissolved from rye breads and sugars from wheat bread. The relevance of food structure to satiety was explored in the second part of the study. Among rye products with different structures and similar chemical compositions, portions of wholemeal rye bread or extruded wholemeal rye puffs and juice were more effective than the portion of extruded wholemeal rye flakes and juice to maintain some aspects of satiety. Intense oral processing did not relate to satiety response but perceived pleasantness and satiety expectations did. Less pleasant food portions resulted in enhanced satiety as well as those that were anticipated already prior to ingestion to be satiating. Oat bran added to juice was more effective in maintaining the feelings of satiety and fullness compared to oat bran incorporated in biscuit matrix. The results showed that disintegration of bread structure and the release of compounds differed between bread types already in mastication. The current study was the first to explore the dissolution of compounds from food, namely bread, after mastication using non-targeted metabolomics approach. The significance of the released compounds warrants further research. The study also showed that food structure is of importance for the postprandial satiety responses of high fibre cereal foods. Perceptions of food, such as liking and expectations, as well as interactions of solid and liquid components (hydration and dissolution) of meal in stomach, are suggested to explain the observed differences in satiety responses.
... Other important parameters can be studied simultaneously such as the initial rate of eating and changes in the rate of eating (Laessle andGeiermann, 2012). This is particularly important for investigations of satiation when sensory characteristics have been manipulated, for example altering the palatability of a food (Yeomans et al 2005) or when comparing populations with binge eating or other eating problems (e.g. Schulz and Laessle, 2012). ...
Chapter
This chapter provides a basic background to sensory-specific satiation and satiety, the typical time-dependent methods used to measure these processes, recent methodological developments which have enhanced the understanding and some guidance on how to conduct these experiments. Sensory-specific satiety is a basic and adaptive feature of eating behaviour expressed by a number of different species and across the lifespan in humans. A variety of techniques are used to study sensory-specific satiety from the subjective and relatively simple self-report through to complex and intricate measures of brain activation during food cue presentations using functional imaging. Measuring the pleasantness of the sensory characteristics of a food in humans involves self-reported judgements of pleasantness. The chapter presents a case study that explores the effects of varying the protein content of a lunch meal on appetite and sensory-specific satiety.
... To further understand the link between real-time vibrotactile feedback, eating rate and food intake, future research might examine whether and how initial motivation to change one's eating rate or motivation to reduce food intake is affected by vibrotactile feedback. Finally, it has been argued that people may need to learn to associate the link between a slower eating rate, their satiety levels and energy intake (Brunstrom, 2011;Yeomans, Weinberg, & James, 2005). Although previous research has demonstrated the effects of a decelerated eating rate on food intake during a single meal (cf. ...
... A number of studies have indicated that "liquid" energy fails to suppress subjective appetite (Leidy, Apolzan, Mattes, & Campbell, 2010;McCrickerd, Chambers, Brunstrom, & Yeomans, 2012), eliciting weaker suppressive appetite responses than "more solid" iso-caloric versions of the same food product (Bertenshaw et al., 2009;Mattes & Rothacker, 2001;Zijlstra, Mars, Stafleu, & de Graaf, 2010). According to McCrickerd et al. (2012), the possible reason is that longer oro-sensory exposures contribute to the development of satiety through triggering anticipatory responses related to learned associations between the sensory characteristics of a food and its caloric value post-consumption (Yeomans, Weinberg, & James, 2005). These associations are likely to influence explicit expectations about the effect a food will have on appetite (Blundell et al., 2010;Brunstrom, Shakeshaft, & Scott-Samuel, 2008). ...
Article
'Satiation' and 'satiety' are key terms that have come to be widely used to help understand processes involved in appetite control. Satiation is considered to be the signals or processes that bring a meal to an end, whereas satiety is the signals or processes, following the end of a meal, that inhibit eating before hunger returns. Protein is the most effective food macronutrient providing a satiating effect. Thus, formulating foods with increased protein contents can help to modulate food intake, promoting body weight loss and body weight maintenance thereafter. Mechanisms explaining protein-induced satiety are primarily nutrient-specific, but they are of course not mathematically related to satiety. Different proteins cause different nutrient-related responses of anorexigenic hormones. Glucagon-like peptide-1 (GLP-1) release evoked by a high protein meal is stimulated by the carbohydrate content. Also, cholecystokinin (CCK) and peptide YY (PYY) release is stimulated by a high-protein meal. Sensory, cognitive, post-ingestive and post-absorptive signals will determine jointly the feeling of satiation and satiety. Oral perception cues also contribute increased expectations of satiating capacity when the oral residence time and in-mouth handling are longer and more laborious. In the present review, the authors want to obtain an overview of the satiating ability of dietary protein and its role in satiation and satiety. This could be really significant in showing the food industry the path for developing protein-rich satiating foods in response to consumer demand.
... Finally the presence of high content of polyphenols in the RSP meal compared to the CP and WSP meals may have contributed to the improved appetite sensations and reduced energy intake at the subsequent lunch. In a recent review by Panickar In addition to the nutrient composition of food, several other factors including weight or volume of a food (portion size), energy density and palatability could also affect satiety and energy intake (Ello-Martin, Ledikwe, & Rolls, 2005;Rosen et al., 2011a;Yeomans, Weinberg, & James, 2005). However, in the present study the portion size, energy density and macronutrient content of the pasta meals were matched and there were no significant differences in the palatability among the test meals. ...
... Thus, the organism requires mechanisms that monitor the amount and calories absorbed. Sight, taste, or smell which detect food to be ingested likely are involved as monitoring mechanisms (Yeomans, Weinberg, & James, 2005;Woods, 2004). French and Cecil (2001) indeed concluded that satiety is dependent on taste. ...
Thesis
During the last decade, anatomic and physiological neuroscience research has yielded extensive information on the physiological regulators of short-term satiety, visceral and interoceptive sensation. Distinct neural circuits regulate the elements of food ingestion physiologically. The general aim of the current studies is to elucidate the peripheral neural pathways to the brain in healthy subjects to establish the groundwork for the study of the pathophysiology of bulimia nervosa (BN). We aimed to define the central activation pattern during non-nutritive gastric distension in humans, and aimed to define the cognitive responses to this mechanical gastric distension. We estimated regional cerebral blood flow with 15O-water positron emission tomography during intragastric balloon inflation and deflation in 18 healthy young women of normal weight. The contrast between inflated minus deflated in the exploratory analysis revealed activation in more than 20 brain regions. The analysis confirmed several well known areas in the central nervous system that contribute to visceral processing: the inferior frontal cortex, representing a zone of convergence for food related stimuli; the insula and operculum referred to as “visceral cortex“; the anterior cingulate gyrus (and insula), processing affective information; and the brainstem, a site of vagal relay for visceral afferent stimuli. Brain activation in the left ventrolateral prefrontal cortex was reproducible. This area is well known for higher cognitive processing, especially reward-related stimuli. The ventrolateral prefrontal cortex with the insular regions may provide a link between the affective and rewarding components of eating and disordered eating as observed in BN and binge-eating obesity. Gastric distension caused a significant rapid, reversible, and reproducible increase in the feelings of fullness, sleepiness, and gastric discomfort as well as a significant rapid, reversible, and reproducible decrease in the feeling of hunger. We showed that mechanical activation of the neurocircuitry involved in meal termination led to the described phenomena. The current brain activation studies of non-painful, proximal gastric distension could provide groundwork in the field of abnormal eating behavior by suggesting a link between visceral sensation and abnormal eating patterns. A potential treatment for disordered eating and obesity could alter the conscious and unconscious perception and interoceptive awareness of gastric distension contributing to meal termination.
... A low SQ in response to a fixed-energy meal has been shown to be associated with greater subsequent ad libitum energy intake measured under both laboratory [8,9] and free-living conditions [9]. The SQ has been used in a wide range of research and has been shown to have value in studies examining acute [12] and long term human appetite control [13] and in research examining the effects of drugs on appetite [14]. Using the SQ, research has demonstrated that the low satiety phenotype is characterised by greater levels of state anxiety and night eating symptoms, an external locus of hunger, and a blunted cortisol response to a standard test meal, suggesting the low satiety phenotype may experience some level of hypothalamic-pituitary-adrenal (HPA) axis activity dysregulation [10]. ...
Article
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Some individuals exhibit a weak satiety response to food and may be susceptible to overconsumption. The current study identified women showing consistently low or high satiety responses to standardised servings of food across four separate days and compared them on behavioural, psychological and physiological risk factors for overeating and future weight gain. In a crossover design, 30 female participants (age: 28.0 ± 10.6; body mass index (BMI): 23.1 ± 3.0) recorded sensations of hunger in the post-prandial period following four graded energy level breakfasts. Satiety quotients were calculated to compare individuals on satiety responsiveness across conditions. Body composition, resting metabolic rate (RMR), energy intake, food reward and craving, and eating behaviour traits were assessed under controlled laboratory conditions. A distinct low satiety phenotype (LSP) was identified with good consistency across separate study days. These individuals had a higher RMR, greater levels of disinhibition and reported feeling lower control over food cravings. Further, they consumed more energy and exhibited greater wanting for high-fat food. The inverse pattern of characteristics was observed in those exhibiting a consistently high satiety phenotype (HSP). Weak satiety responsiveness is a reliable trait identifiable using the satiety quotient. The LSP was characterised by distinct behavioural and psychological characteristics indicating a risk for overeating, compared to HSP.
... those responding to the conventional homeostatic model of appetite control; Blundell and Finlayson 2008). For instance, food liking and wanting in humans can override the inhibitory effects of satiety signals and actually increase food intake (Yeomans et al. 2001(Yeomans et al. , 2005; see also papers in Blundell and Bellisle 2013). ...
Article
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Conventional models of foraging, such as optimal foraging theory, generally take the univariate approach to explain the decisions of consumers on the basis of the intrinsic properties of foods, including nutrient concentration and abundance. However, the food environment is inherently diverse and, as a consequence, foraging decisions are influenced by the interactions among multiple food components and the forager. Foraging behaviour is affected by the consumer's past experiences with the biochemical context in which a food is ingested, including the kinds and amounts of nutrients and plant secondary compounds in a plant and its neighbours. In addition, past experiences with food have the potential to influence food preference and intake through a mechanism, namely, food hedonics, which is not entirely dependent on the classical homeostatic model of appetite control. Research on the impacts of experience with food context and its behavioural expression in natural settings should pioneer innovative management strategies aimed at modifying food intake and preference of herbivores to enhance their nutrition, health and welfare, as well as the health and integrity of the landscapes they inhabit.
... Oro-sensory exposure to food is thought to trigger anticipatory responses because animals, including humans, learn to associate the sensory characteristics of a food with its caloric value post-consumption [20][21][22][23], and these associations are likely to influence explicit expectations about the effect a food will have on appetite [24,25], including how filling a food is likely to be (expected satiation) and the extent to which it will stave off hunger until the next meal (expected satiety): such expectations have been shown to influence appetitive satisfaction and portion size selection [26][27][28] and seem to be more strongly influenced by certain sensory characteristics. For example, a food is expected to be more filling when it is perceived to be heavier [29] or thicker in texture [30]. ...
Conference Paper
Previous research indicates that small increases in satiety-relevant orosensory properties (thick mouthfeel and creamy flavour) enhance the satiating effects of a high energy drink. One explanation is that orosensory cues generate expectations that a food will be filling which enhances our physiological responses to nutrients. Two studies investigated the extent to which small changes in drink viscosity are perceived and the role of such sensory cues in the generation of satiety expectations. In Study 1, 24 participants (12 male) rated the sensory properties of 16 fruit yogurt drinks of increasing viscosity. In Study 2, 25 participants (9 male) evaluated 8 versions of the fruit yogurt drink for sensory and hedonic properties and satiety expectations. The drinks consisted of high and low energy versions in four sensory contexts: low sensory, creamy, thick, high sensory (thick and creamy). Results from Study 1 indicate that participants were able to perceive small changes in drink viscosity (p< 0.001), showing good test–retest reliability. In Study 2 we observed significant effects of sensory context on both satiety expectations (p< 0.001) and filling ratings (p< 0.001) with no effect of energy content. These findings indicate that untrained participants are sensitive to the sensory properties of a drink and small manipulations of texture and flavour increase expectations that a fruit yogurt drink will be filling and suppress hunger, independent of its actual energy content. Prospective research will investigate the impact of such expectations on satiation in a drink context.
... Fewer studies have investigated the effects of macronutrients on intrameal energy intake. Consistent evidence shows that high-fiber meals can lead to a longer chewing time and increased gastric distension resulting in earlier sense of fullness (4,36) and earlier meal cessation and reduced energy intake (10,38,39). The fiber content of the LB was Ȃ6 g/1000 kJ greater than that of the WB. ...
Article
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Article
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Purpose The energy density (ED) of a diet can be leveraged to prevent weight gain or treat overweight and obesity. By lowering the ED of the diet, energy intake can be reduced while maintaining portion size. However, a reliable meta-analysis of data from randomized controlled trials (RCTs) is missing. Therefore, this meta-analysis synthesized the evidence of ED manipulation on energy intake in RCTs. Methods The systematic literature search of multiple databases according to PRISMA criteria considered RCTs investigating the objectively measured energy intake from meals with different ED (lower ED (median 1.1 kcal/g) versus higher ED (median 1.5 kcal/g)) under controlled conditions. Subgroup analyses for age (children versus adults), meal type (preload versus entrée design), and intervention length (1 meal versus > 1 meal) were performed to achieve the most homogeneous result. Results The meta-analysis of 38 included studies demonstrated that lowering ED considerably reduced energy intake – 223 kcal (95% CI: – 259.7, – 186.0) in comparison to the higher ED interventions. As heterogeneity was high among studies, subgroup analyses were conducted. Heterogeneity decreased in subgroup analyses for age and meal type combined, strengthening the results. An extended analysis showed a positive linear relationship between ED and energy intake. Dietary ED did not affect the amount of food intake. Conclusion Manipulating ED substantially affects energy intake whereas food intake remains constant. Thus, this approach can be regarded as a powerful tool for weight management through nutrition therapy. Registration on 08/08/2021: CRD42021266653.
Chapter
Flavor perception has several characteristics: (1) smell is a key part, but there is little awareness of its role; (2) central interactions occur between smell, taste, and somatosensation; (3) flavor is localized to the mouth; (4) discontinuities in odorant delivery are not noticed; and (5) there is limited access to some parts. Together, these suggest flavor is partially holistic, with odor and taste forming a common sensory channel in the mouth. One reason for this mode of perception is food choice. Flavor memories can support the identification of safe and nutritious food via: (1) recovery of the flavor percept—thus including taste (and somatosensory) experiences—via sniffing; (2) visual priming of flavor expectancies; and (3) affective reaction to flavor, reflecting the consequences of previous bouts of ingestion (e.g., sickness). These allow food acceptability to be assessed prior to ingestion, as well as supporting the expectancies to detect adulterated food.
Chapter
In this chapter, the authors present a broad view of the current background to the obesity pandemic and the importance of eating behavior. By examining differences in factors known to affect appetite regulation in individuals identified as “resistant” or “susceptible” to weight gain, they show how appetite processes mediate the relationship between differences in an individual's biology, physiology, and psychology and their eating behavior, and their response to (variations in) the environment. One approach to characterizing individual susceptibility is through the identification and characterization of phenotypes. Under controlled laboratory conditions, appetite sensations have been shown to be a valid and reliable method for measuring subjective motivation to eat and have been found to be associated with measured energy intake. However, not everyone reports a good relationship between their sensations of hunger and fullness and their eating behavior, and a weakened satiety response to food may contribute to impaired appetite control.
Chapter
The scientific study of human appetite and eating behavior has become increasingly important in recent years due to the rise of body fat dysregulation and the conditions of obesity, diabetes and eating disorders. In addition, changes in appetite occur in several other disease states and physical conditions affecting general health. For these reasons a strong methodology is required to ensure objective and quantifiable measures of appetite behavior and associated psychological sensations. The use of a multi-level research platform can help the alignment of psychological, behavioral and physiological variables. The Satiety Cascade provides a graphic formulation for clarifying distinct measurable variables such as hunger, satiation and satiety. An agreed methodology allows outcomes from different studies to be compared. Specific experimental designs, measurement instruments, and standard operating procedures have been developed to ensure good conduct. Several study designs are widely used and can be deployed to answer specific research questions. Specific procedures have been developed for the measurement of homeostatic and hedonic processes involved in appetite. A case study of the comprehensive assessment of a potential anti-obesity drug is described as a model procedure. Good Laboratory Practice applies in this field as in other areas of biomedical research.
Article
Eating rate is a basic determinant of appetite regulation, as people who eat more slowly feel sated earlier and eat less. Without assistance, eating rate is difficult to modify due to its automatic nature. In the current study, participants used an augmented fork that aimed to decelerate their rate of eating. A total of 114 participants were randomly assigned to the Feedback Condition (FC), in which they received vibrotactile feedback from their fork when eating too fast (i.e., taking more than one bite per 10 seconds), or a Non-Feedback Condition (NFC). Participants in the FC took fewer bites per minute than did those in the NFC. Participants in the FC also had a higher success ratio, indicating that they had significantly more bites outside the designated time interval of 10 seconds than did participants in the NFC. A slower eating rate, however, did not lead to a significant reduction in the amount of food consumed or level of satiation. These findings indicate that real-time vibrotactile feedback delivered through an augmented fork is capable of reducing eating rate, but there is no evidence from this study that this reduction in eating rate is translated into an increase in satiation or reduction in food consumption. Overall, this study shows that real-time vibrotactile feedback may be a viable tool in interventions that aim to reduce eating rate. The long-term effectiveness of this form of feedback on satiation and food consumption, however, awaits further investigation.
Chapter
Intake is one of the most essential behaviors since all living organisms require adequate nutrients for survival. Ingestive behavior is a complex phenomenon under the influence of three main mechanisms: homeostatic, hedonic, and cognitive. The sensory perception resulting from the taste, odor, texture, and temperature of the food, that is, its flavor, allow us to analyze, identify and eventually recognize the food and will then be a central contributor in the decision to ingest or reject the food. The treatment of sensory information (perception) is a complex multimodal process. Food seeking and ingestion are also influenced by (1) memories of the orosensory, olfactory and postingestive effects of previous encounters with a similar substance; and (2) emotional, cognitive and social factors such as culture and context. This aim of this chapter is to describe some of these mechanisms as well as their time course through the alimentary sequences.
Chapter
Flavor perception supports food choice, and it has several characteristics: (1) smell is a key part, but there is little awareness of its role; (2) variations in odorant delivery are not noticed; (3) flavor is localized to the mouth; (4) central interactions occur between all flavor senses; and (5) there is limited access to some sensory components. Together, these suggest flavor perception is partially holistic, with odor and taste forming a common sensory channel in the mouth. One reason for this mode of perception is food choice. Flavor memories can support the identification of nutritious food via: (1) recovery of the flavor percept—thus including taste and somatosensory experiences—via sniffing; (2) visual priming of flavor expectancies; and (3) affective reaction to flavor, reflecting the effects of previous bouts of ingestion (eg, sickness). These allow food acceptability to be assessed prior to ingestion, as well as supporting the detection of adulterated food.
Chapter
This chapter discusses the current understanding of the role of palatability in appetite control in humans. It focuses on the phenomenology of palatability effects, theoretical interpretations of palatability effects, and the relationship between palatability and homeostatic controls of eating. It also focuses specifically on obesity, and explores whether individual differences in response to palatability might explain phenotypical variation in susceptibility to weight gain, and how increased understanding of the role of palatability in appetite control might inform the future treatment and prevention of obesity. Over-consumption of palatable foods is one of the factors contributing to the current worldwide increase in the incidence of obesity. Palatability effects reflect stimulation of central reward systems by the sensory qualities of foods, and that these effects interact with satiety mechanisms to determine meal size. Appetite stimulation is a direct function of perceived palatability, with incremental increases in intake, as foods become more liked. Most food likes are acquired responses. Enhanced responsivity to palatability may underlie the failure to respond to obesity treatment, and that future treatments are likely to benefit by the inclusion of strategies or specific drug treatments that ameliorate the role of palatability in subsequent overeating.
Chapter
The present chapter describes the influence of satiety on intake as it occurs in the complex, multi-determinant environments where intake normally occurs. Rhythms, social facilitation, stomach contents, palatability, dietary density, restraint, and the built environment have all been shown to have significant, genetically affected, influences on intake, independent of each other and of the influence of satiety. Hence, in the real-world environments of humans, satiety appears to play a role affecting intake, but its impact is relatively small and embedded among a myriad of other factors.
Book
The current approach for evaluating feelings of satiety using visual analog scales (VAS) is well developed. Although widely validated, there are certain limitations inherent to VAS, such as the difficulty of understanding and using them or the limited introspection naïve consumers have for evaluating appetite sensations. The hypothesis of the new approach presented here is that selecting sensory panelists used to evaluating feelings about foods, then giving them specific training followed by application to foods in the assessment of appetite feelings provides more discriminative results.
Chapter
Food choice and energy intake are often motivated by the expectation or experience of pleasure (wanting and liking for food). An extension to the conventional 'homeostatic' model of appetite control recognises that these 'hedonic' aspects operate through their interaction with episodic mechanisms involved in satiation and satiety. More recently, evidence is emerging to show how tonic signals from nutrient status and energy balance affect liking and wanting to influence food preference and nutrient composition of the diet. Finally, enhanced hedonic response to highly palatable foods predicts loss of appetite control; raising the question of whether liking or wanting could be targeted to reduce overconsumption.
Chapter
The human diet is extremely varied, and humans have the ability to recognize valuable sources of nutrition while avoiding items which are poisonous. Critical to this ability is an appetite control system that facilitates the development of liking for the flavor of foods which provide nutritional or other benefits, ambivalence to items with little or no benefit, and dislike of items which are harmful. These acquired likes and dislikes guide food choice, and in part determine the amount we consume. As this chapter details, since it is clear that we rapidly acquire a liking for energy-dense foods, the system which underlies flavor preference development may also contribute to overconsumption and consequent risk of obesity. This chapter therefore explores current theories of how we acquire flavor likes and dislikes, examines the impact of these changes on eating behavior, and considers how individual differences in the ability to acquire such preferences may be a risk factor for development of obesity.
Article
Drivers of liking (DOL) studies are useful for product development to formulate acceptable products; however, DOL alone are insufficient for understanding why a product is purchased and repurchased, which is ultimately the indication of a successful product. Ultimately sensory attributes drive product success (that is, repeat and continued purchase). However, ignoring the importance of extrinsic factors may neglect the vital product attributes responsible for the initial purchase, which may in turn, affect repeat purchase. The perception of sensory attributes assessed by DOL is mitigated by external perceptions of quality. If the sensory attributes do not deliver based upon the quality cues, the product will not be acceptable. Four key extrinsic factors that affect DOL are the perceived satiety, brand and labeling, price, and the emotional impact to decision making. In order to more thoroughly understand what the DOL for a product is, these 4 product cues should be considered in conjunction with sensory attribute perception to gain a holistic understanding of product acceptance. © 2015 Institute of Food Technologists®
Article
Designing food items with high satiating capacity is an area of increasing interest. It would be desirable for consumers to be able to make informed choices about individual products based on understanding the energy balance and the meaning of satiety. In the present work, the perceptions that consumers have of the word "satiating" and of different protein-based dishes were investigated in two populations (100 subjects related to the field of food science and technology and 100 unrelated to it). The Word Association (WA) technique was used, asking the consumers for the first four words that came into their mind when they thought of "satiating food". This was followed by a Free Listing (FL) exercise that asked them to list four satiating food items, They also completed a Nutritional Knowledge Questionnaire. To evaluate the consumers' perception of the expected satiating capacity of different protein-based meals, they were shown eight photographs of equicaloric dishes composed of one piece of protein (beef, pork, chicken or fish) and one of two different side vegetables (salad or boiled potatoes). The expected satiety scores ranked fish last among the protein foods and potatoes last among the side vegetables. The results indicated that "satiating" food was related more with the immediate sensation of "stomach full" than with the cessation of hunger. This was reinforced by the mention of negative sensations of discomfort after a copious meal. Hearty dishes and meat were the meals most associated with satiating food items.
Article
Abstract Abstract Since protein has been shown to have the highest satiating-inducing effects of all the macronutrients, increasing the protein level is one of the main strategies for designing food with enhanced satiating capacity. However, few studies analyze the effect that protein addition has on the texture and flavor characteristics of the target food item to relate them to the expected satiating capacity it elicits. The present work studied cheese pies with three levels of soy and whey proteins. Since the protein level altered the rheological behavior of the batters before baking and the texture of the baked pies, the feasibility of adding several protein levels for obtaining a range of final products was investigated. A Check-all-that-apply question containing 32 sensory and non-sensory characteristics of the samples were performed with consumers (n=131) who also scored the perceived samples’ satiating capacity. The results showed that the type and content of protein contributed distinctive sensory characteristics to the samples that could be related to their satiating capacity perception. Harder and drier samples (high protein levels) were perceived as more satiating with less perceptible sweet and milky cheese pie characteristic flavors Soy contributed off-flavour. These results will contribute a better understanding of the interrelation of all these factors, aiding the development of highly palatable solid foods with enhanced satiating capacities.
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The role of dietary energy density (ED) in the regulation of energy intake (EI) is controversial. Methodologically, there is also debate about whether beverages should be included in dietary ED calculations. To address these issues, studies examining the effects of ED on EI or body weight in nonelderly adults were reviewed. Different approaches to calculating dietary ED do not appear to alter the direction of reported relations between ED and body weight. Evidence that lowering dietary ED reduces EI in short-term studies is convincing, but there are currently insufficient data to determine long-term effectiveness for weight loss. The review also identified key barriers to progress in understanding the role of ED in energy regulation, in particular the absence of a standard definition of ED, and the lack of data from multiple long-term clinical trials examining the effectiveness of low-ED diet recommendations for preventing both primary weight gain and weight regain in nonobese individuals. Long-term clinical trials designed to examine the impact of dietary ED on energy regulation, and including multiple ED calculation methods within the same study, are still needed to determine the importance of ED in the regulation of EI and body weight.
Article
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The study of human appetite and eating behaviour has become increasingly important in recent years due to the rise in body weight dysregulation through both obesity and eating disorders. Adequate control over appetite is paramount for the control of body weight and in order to understand appetite, it is necessary to measure eating behaviour accurately. So far, research in this field has revealed that no single experimental design can answer all research questions. Each research question posed will require a specific study design that will limit the findings of that study to those particular conditions. For example, choices will be made among the use of laboratory or free-living studies, time period for examination, specific measurement techniques and investigative methodologies employed. It is important that these represent informed decisions about what design and which methodology will provide the most meaningful outcomes. This review will examine some of the 'gold standard' study designs and methodologies currently employed in the study of human appetite and eating behaviour.
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Background: Foods that are high in dietary fiber can promote satiety, but previous studies report conflicting results. Objective: The objective was to determine differences in satiety response to three conditions (10 g oat bran, 10 g barley bran and a low fiber condition) consumed at dinner and breakfast. In addition, we compared energy intake at an ad libitum lunch after consumption of the breakfast bars. Design: Randomized, double-blind crossover study. Participants/setting: 42 normal weight women. Intervention: Women consumed a dinner food bar from one of the three conditions the evening before testing. On test mornings, fasted women consumed the corresponding breakfast food bar with their choice of coffee, tea or water. An ad libitum pizza lunch was served 4 hours after breakfast. Primary outcomes: Visual analogue scales (VAS) were used to assess satiety at baseline, 15, 30, 45, 60, 90, 120, 180 and 240 minutes. Energy intake was assessed by an ad libitum pizza lunch (4 hours after breakfast) and 24-hour energy intake was measured by a food diary. Statistical analyses: Treatments were compared using the mixed-effects linear models. Outcomes are reported as mean ± SEM. Results: There were no significant differences among conditions on any of the satiety scales and no significant differences among conditions in energy consumed at lunch or over 24 hours. The fiber bars were well tolerated and no significant differences were found for gastrointestinal tolerance. Conclusions: Our results do not support an effect of bran fibers on satiety above a low fiber control. We acknowledge results of this study may be intricately tied to the choice of a single pizza lunch, as other ad libitum meal options could have resulted in different outcomes.
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Sensory properties guide the amount that people eat. In particular, food texture plays an important role in a food's 'expected satiation', which in turn affects the food-related decision making process. One hypothesis is that incongruent pairing of a textural cue with a post-ingestive outcome compromises this process, leading to poor energy compensation. Several studies examined the effect of both energy density and sensory characteristics (i.e. increased creaminess and thickness) on expectations, subjective appetite and food intake. To add to this literature, a re-analysis of data assessed whether the effect of sensory-nutrient pairings on energy intake compensation persisted after repeated exposure to a food. In this cross-over design, 27 participants consumed two preloads with 'congruent' (low-energy/liquid; high-energy/semi-solid) and two preloads with 'incongruent' (low-energy/semi-solid; high-energy/liquid) texture-nutrient combinations during nine subsequent meals, during which ad libitum intake was measured. Intake at first exposure did not differ between the low-energy (280±150kcal) or high-energy preload (292±183kcal) in the incongruent conditions. By contrast, it was greater after the low-energy (332±203kcal) than after the high-energy (236±132kcal) preload in the congruent conditions (energy * incongruent/congruent, p=0.04). Post-exposure, this pattern changed: intake depended on the energy density of the preloads in all conditions, and was greater after low-energy preloads (day * energy * incongruent/congruent-interaction for breakfast: p=0.02). Thus, manipulating the sensory properties of a food influenced energy compensation and meal size, but only at initial exposure. Repeated exposure 'corrected' the initial lack of compensation observed in conditions with incongruent sensory-nutrient pairings.
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The hedonic element of eating is much harder to measure than has traditionally been assumed, in and out of psychology. Nothing is gained, and much is lost, by careless extension of the idea of hedonic experience to the observed behavioral dispositions of conditioned preferences and appetites.
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The adaptive importance of acquired feeding habits has long been acknowledged in research on obesity1 and animal foraging2 for example. Yet so few experiments have measured learning under physiologically and ecologically normal conditions that there is insufficient information for effective applications in the clinic and everyday life,3 the foods4 or Pharmaceuticals5 industries, or animal husbandry.6 Nevertheless, it has been established that normal feeding in the laboratory rat is associatively conditioned by nutritional consequences.7–11 Occasionally, aversions are conditioned. However, what is usually learned is facilitation of feeding (Table 1), which accounts for much of the incentive to forage and the palatability of foods and drinks.13
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In 3 experiments with a total of 72 male albino Wistar or Sprague-Dawley rats, liquid or solid diets differing in carbohydrate or triglyceride content were presented 1 at a time to each S once or twice a day. For a given S, each caloric density consistently had a particular odor and/or taste. Results show the size of the feeding bout on the dilute nutrient became larger than that on the more concentrated nutrient after several pairs of presentations. This differentiation was at least partly controlled by the oral cues which had been paired with nutrient differences. Results were attributable to acquired differences in the development of feeding inhibition during the meal, and not to original or acquired differences in initial rate of feeding or in the preference for 1 diet over the other in 2 stimulus tests. (33 ref.)
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Obesity is a multifactorial and complex affectation that is characterized by a long-term excess energy intake (EI) above energy expenditure (EE). Since fat oxidation seems to be dependent on SNS activation and also seems to remain acutely unaffected by fat intake, this macronutrient is certainly partly responsible for this situation. In addition, high-fat intake does not induce as potent satiety signals or a compensation effect on subsequent EI as do diets rich in carbohydrates or proteins. Moreover, since alcohol intake acutely inhibits fat oxidation and does not promote subsequent compensation for its energy content, it should consequently be regarded as a substrate which can induce a positive energy balance under free-living conditions. Thus, in a weight reducing context, each energy substrate should be manipulated while taking into account its specific characteristics. Obesity has also often been associated to a decreased sympathetic nervous system (SNS) activity, hence sympathomimetic agents have been proposed as a possible way to partially correct this situation. Two of these agents are the widely consumed caffeine (CAF) and the pungent principle of hot red pepper, capsaicin (CAP), which acutely increase EE and reduce EI under some circumstances. Furthermore, other factors like dietary fibers, that have been shown to increase satiety and fullness, and reduce EI in some cases, should also be considered.
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This study examined the effects of varying the energy density (ED) of high carbohydrate (HC) diets on food and energy intake (EI), subjective hunger and body weight in humans. Randomised cross-over design. Subjects were each studied twice during 14 d, throughout which they had ad libitum access to one of two covertly-manipulated diets. Six healthy men (mean age (s.d.)=32.17 y s.d. (5.26 y), mean weight=69.74 kg s.d. (2.75 kg), mean height=1.76 m s.d. (0.05 m), body mass index (BMI)=22.57 (2.2) kg/m2) were studied. The fat, carbohydrate (CHO) and protein content (as % energy) and ED of each diet were 21:66:13% and 357 kJ/100 g, (low-energy density (LED)) or 22:66:12% and 629 kJ/100 g (high-energy density (HED)). A medium fat diet was provided at maintenance (1.6 x BMR, MF for 2 d) before each ad libitum period. Subjects could alter the amount, but not the composition of foods eaten. Mean EI was 8.67 and 14.82 MJ/d on the LED and HED diets, respectively. Subjects felt significantly more hungry on the LED diet, than on the HED diet (F(1,160)38.28; P < 0.001) and found the diets to be similarly pleasant (72.72 mm vs 71.54 mm (F(1,392)0.31; P = 0.579)). Mean body weight decreased on the LED diet at a rate of 0.1 kg/d and increased at 0.06 kg/d on the HED diet (F(1,131)86.60; P < 0.001), giving total weight changes of -1.41 kg and +0.84 kg, respectively, both of which were significantly different from zero (P < 0.01). Excess EI is possible on HC, HED diets, at least under conditions where diet selection is precluded. Comparison of these results with previous studies, which altered ED using fat, suggests that CHO may be a better cue for hunger than fat.
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This study examined the effects of covert alterations in the energy density (ED) of mixed, medium fat (MF) diets on ad libitum food and energy intake (EI), subjective hunger and body weight in humans. Randomised cross-over design. Subjects were each studied three times (factorial design), during 14d, throughout which they had ad libitum access to one of three covertly-manipulated MF diets. Six healthy men, mean age (s.e.m.) = 30.0 y (12.76 y), mean weight = 71.67 kg (19.80 kg); mean height = 1.79 m (0.22 m), body mass index (BMI) = 22.36 (2.60) kg/m2, were studied. The fat, carbohydrate (CHO) and protein in each diet (as a proportion of the total energy) and energy density (ED) were, low-ED (LED), 38:49:13%; 373 kJ/100 g; medium-ED (MED), 40:47:13%; 549 kJ/100 g; high-ED (HED), 39:48:13%; 737 kJ/100 g. Subjects could alter the amount but not the composition of foods eaten. They were resident in (but not confined to) a metabolic suite throughout the study. Solid food intake decreased as ED increased, giving mean values of 2.84, 2.51 and 2.31 kg/d, respectively. This was insufficient to defend energy balance, since energy intake increased with increasing ED (F(2,10) 16.08; P < 0.001) giving mean intakes of 10.12, 12.80 and 16.17 MJ/d, respectively. Rated pleasantness of food (measured on visual analogue scales) was not significantly different between diets nor was subjective hunger different between the LED, MED and HED diets, respectively. Diet significantly affected body weight (F(2,10) = 4.62; P = 0.038), producing changes of -1.20, 0.02 and 0.95 kg, respectively, by day 14. Dietary ED can influence EI and body weight, since changes in amount eaten alone are insufficient to defend energy balance, when subjects feed on unfamiliar diets and diet selection is precluded. Comparison with our previous studies suggest that there was compensation in solid food intake when ED was altered using mixed diets (as in this study) compared to previous studies which primarily used fat or CHO to alter dietary ED.
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To test whether the palatability of a test meal altered compensatory eating following disguised high-energy fat and carbohydrate preloads. Effects of preload energy (low, 265 kJ, or high, 1510 kJ) and test-meal palatability (bland or palatable) were contrasted within-subjects, with a between-subjects contrast of fat and carbohydrate preloads. Twenty-four healthy, normal men (age 23.6+/-1.0 y, (body mass index) BMI 21.3+/-0.5). Microstructural analysis of test meal intake and rated appetite in the four test conditions, plus diary-based weighed intake analysis of energy intake post-lunch. Subjects ate significantly less at lunch after disguised high-energy fat or carbohydrate preloads relative to the low-energy preload, and ate significantly more of the palatable than bland lunch in all conditions. The reduction in eating following the high-energy preload was significantly less in the palatable condition. Intake post-lunch did not differ between conditions, and overall subjects had higher daily energy intake on the days they consumed the high-energy preloads. Rated hunger was significantly less 30 min after the high- than low-energy preloads, but increased on tasting the palatable food in all conditions. The high-energy preloads suppressed appetite immediately post-lunch. No differences between fat and carbohydrate were found on any measure. Manipulation of the palatability of a test meal modified the ability to respond to disguised high-energy preloads, with over-consumption most evident when disguised high-energy preloads were followed by a palatable food. Subsequent voluntary intake compensated for over-consumption of the palatable lunch, but not the high-energy preload.
Article
This study was carried out to disclose effects generated by the uncoupling of the sensory and energetic components of sweet solutions. A comparison was made between equi-sweet preloads of three intense sweeteners (saccharin, aspartame and acesulfame-K), a bulk sweetener (glucose) and a nonsweet water control. Measures were made of subjective ratings of motivation to eat, food preferences and energy intake in a test meal. The glucose load produced a consistent pattern of changes on all measures. The intense sweeteners tended to facilitate motivational ratings and food preference checklist responses, but marginally lowered intake in the test meal. The facilitative action is probably due to the stimulation of sensory receptors for sweetness by the high-intensity agents, while the effects on intake are most likely due to a ceiling effect imposed by methodological limitations of this particular design. The results of this study must be interpreted with reference to the prevailing experimental conditions, but they suggest that intense sweeteners can produce significant changes in appetite. Of the intense sweeteners, aspartame gave rise to the most pronounced effects.
Article
Lean male and female subjects who had been taking their meals as usual were given a 100 ml drink of starch immediately before a sandwich lunch. In the training phase,65 per cent starch was given before lunches which included a yoghurt-based dessert of one flavour and 5 per cent starch was given before another flavour. Subjects who initially ate lunches of similar size following the two drinks began after several pairings to take larger lunches following dilute starch than following concentrated starch. In extinction tests, identical 35 per cent starch drinks were given before lunches including desserts of either flavour. Lunches including the flavour hitherto paired with dilute starch remained larger than lunches including the other flavour, at least initially in extinction. Some of the difference in intake occurred in the dessert itself. None was attributable to differences in the early stage of the lunches. These results extend to man recent demonstrations that the satisfying power of a foodstuff is in part acquired by association of its sensory characteristics with some consequence of ingesting the nutrients which are consistently taken with or in that food. This consequence may be rapid intestinal absorption of glucose during or shortly after sensory input. The nature of the intake-suppressing response remains to be determined.
Article
The objective was to compare taste-and-spit pleasantness ratings of open sandwiches to ratings after ad libitum consumption. In the latter test, open sandwiches were ingested one at a time at a laboratory breakfast. Three rye breads of different acid and NaCl concentrations (non-sour + normal NaCl, sour + low NaCl, sour + normal NaCl) were evaluated with butter or margarine with two levels of NaCl (1 or 2 per cent). Subjects (N = 27) rated the samples more pleasant after consumption than in taste-and-spit tests. Mean pleasantness ratings by sample in taste-and-spit and postconsumption tests correlated with the amount of bread consumed (r = 0.63, r = 0.82, respectively). The taste-and-spit ratings of individual subjects correlated poorly with the amount of bread consumed, only three correlation coefficients out of 27 being significant. Taste-and-spit pleasantness ratings can perhaps be used to predict the average consumption of a product but not consumption by individual subjects. The laboratory tests should be developed further to reflect better food acceptability in natural conditions.
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A high-carbohydrate (CHO) yogurt (81% CHO) and a high-fat yogurt (65% fat), containing similar levels of protein, were given in equal volumes as preloads to 14 normal-weight, nondieting males and 14 normal-weight, nondieting females. The yogurts were formulated to have similar energy densities and sensory properties, so that differences in responses to the preloads would depend on postingestive physiological effects. Three intervals (30, 90, and 180 min) between the preloads and a self-selection meal consisting of a variety of foods were utilized. The self-selection meal was served at the subject's normal lunchtime under all conditions. In the 30-min-delay condition, subjects accurately compensated for the calories in the preloads compared with a no-preload condition, but as the interval increased, compensation was less precise. No significant differences in subsequent food intake were found between the high-CHO and high-fat yogurts at any time interval. Also, there were no differences in ratings of hunger and fullness between the yogurts. The macronutrient composition of the preloads did not affect the types of foods, or macronutrients, consumed at lunch.
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The shape of the cumulative food intake curve of normal weight and obese women was studied during solid food lunches, artificially prolonged meals, and energetically enriched meals eaten in a laboratory setting. Subjects (86 normal weight, 50 obese) displayed consistent eating behaviour over 3-6 repeated meals, with marked differences between individuals. Aspects of eating behaviour were reflected in decelerated and nondecelerated (or linear) cumulative intake curves depending on changes or no changes in eating rate during the course of a meal, respectively. A change in eating rate was generally related to decrease in bite size, with bite rate remaining constant, from the third temporal quarter of the meal onwards, resulting in a decelerated cumulative intake curve. The nondecelerated (linear) cumulative intake curve does not show this change in eating rate: in the first three temporal quarters bite size and bite rate were constant, whereas in the fourth temporal quarter bite size decreased slightly, compensated by a small increase in bite rate. Intraindividual ranges for meal parameters such as chewing time per bite, bite interval and initial eating rate indicated consistency of individual eating behaviour. In manipulation experiments with a subset of 21 subjects in which meals were artificially prolonged by an interval of 8 min, the cumulative intake curves did not differ significantly from the original cumulative intake curves in 10 nondecelerated (linear) eaters, but showed a change towards nondecelerated curves in 8 out of 11 decelerated eaters.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
In this experiment 11 children participated in a series of 8 pairs of conditioning trials in order to investigate the hypothesis that children could form conditioned flavor preferences based on caloric density. Unfamiliar drink flavors were used in these trials, and the drinks were either high in caloric density (155 kcal/150 ml) or low (less than 5 kcal/150 ml). Caloric density was altered by the addition of low glucose maltodextrin. Each child always had the same caloric density/flavor pairing throughout the conditioning trials. Each trial pair included one high and one low density preload, followed by ad lib consumption. These conditioning trials substituted for the children's regularly scheduled morning snack four days per week, one trial per day. Conditioning trials were given as a series of two-part snacks, consisting of fixed volumes of initially unfamiliar drinks, followed by the opportunity to eat a variety of foods ad lib. Two measures, obtained before and after conditioning, provided evidence for the formation of conditioned flavor preferences: 1) preference assessments, and 2) two-flavor choice tests. In addition, the ad lib consumption data indicated that the children were responsive to the caloric density manipulation, by consistently eating more following the low than the high density drink. The potential contribution of such acquired flavor preferences to the reduction of neophobia is discussed.
Article
The effects of preloads, deprivation, and palatability on the eating behavior of non-dieting lean and obese subjects were studied during laboratory meals, using small solid food units (SFUs) to measure the rate of ingestion over the time-course of the meals. In both weight groups, rate of intake decreased from the beginning to the end of meals. The smaller the preloads and the longer the deprivation interval, the faster subjects ate at the beginning of meals and the higher their hunger ratings were. The longest deprivation interval also increased palatability ratings, meal length, and the total amount that subjects ate. Increasing the palatability of the food increased the rate of intake at the beginning of meals, meal length, and the amount of food that subjects ate. Obese subjects were more sensitive to palatability and less responsive to deprivation than lean subjects. For example, while lean subjects became less discriminating about the palatability of the food at the beginning of meals as deprivation increased, obese subjects did not. The satiation mechanism of obese subjects was also different from lean subjects. For example, obese subjects overate after preloads while lean subjects underate compared to their baselines.
Article
The assessment of hunger in human subjects is complicated by the variety of response systems involved. In the present study, hunger was tracked by subjective, physiological and behavioural responses after identical-tasting high or low calorie preloads. The contribution of nutritional and psychological factors was evaluated by giving half the subjects false information about the caloric content of the preload. Ten women took part, with all subjects participating in each experimental condition and a control condition, in counter-balanced order. The results showed that ratings of hunger symptoms, preferred foods, global hunger and satiety in the inter-meal interval were sensitive both to deprivation effects and to differences in the energy content of the preload. No effects of the psychological manipulation (beliefs about caloric content) were observed. At the test meal two hours later, all the subjective responses converged on a single point and physiological and behavioural responses likewise failed to discriminate the different preload conditions. The results are discussed in terms of a loosely-coupled multidimensional model of hunger.
Article
Twenty-one two and half- to five-year-old children and 26 25- to 35-year-old adults participated in an experiment designed to provide evidence for two behavioral mechanisms involved in self regulation of food intake: caloric compensation and sensory specific satiety. All participants were seen in two lunch sessions that differed in the caloric density of the preload presented. To obtain evidence on sensory specific satiety, preference data were obtained immediately before and after, and 20 min after preload consumption. Subjects then ate an ad libitum lunch and consumption was recorded. Both children's and adults' preferences for the food eaten declined relative to foods not eaten, providing the first evidence of sensory specific satiety in children. The patterns of preference did not differ with the caloric density of the food eaten. Children showed much clearer evidence for caloric compensation than did the adults.
Article
This study was undertaken to quantify the relationship between palatability ratings and food consumption and to determine whether the initial rate of eating was affected by changes in food palatability without a change in nutrient content. Both men and women were given small samples of foods at a brief exposure taste test and asked to rate how much they liked or disliked them on a 9-point scale (like extremely to dislike extremely). Those who gave at least a 2-point difference in rating between a banana colada frozen yogurt drink with and without adulteration with cumin were given these foods to eat to satiety on non-consecutive days, and the same 9-point scale was used to rate these foods after they had been eaten as meals. Cumin was used as an adulterant because it is not intrinsically unpalatable, but is not liked by many individuals in yogurt-based foods. Intake was approximately 100 g different for every unit of difference on the scale, and higher for liked than disliked food. Intake was significantly different between the adulterated and unadulterated meals. The percentage of variance explained by the difference in palatability was 34% of the total variance but was 67% of the variance within subjects. Correlation between intake and ratings were poor across subjects for both palatability levels (i.e. adulterated and unadulterated). The initial rate of eating was significantly higher under the better liked than under the less liked food. These results indicate that quantification of effects of hedonic ratings on intake within subjects is possible, but that hedonic ratings may not be good discriminators of intake differences between subjects. The initial rate of eating reflects partly on palatability.
Article
This report describes the construction of a questionnaire to measure three dimensions of human eating behavior. The first step was a collation of items from two existing questionnaires that measure the related concepts of 'restrained eating' and 'latent obesity', to which were added items newly written to elucidate these concepts. This version was administered to several populations selected to include persons who exhibited the spectrum from extreme dietary restraint to extreme lack of restraint. The resulting responses were factor analyzed and the resulting factor structure was used to revise the questionnaire. This process was then repeated: administration of the revised questionnaire to groups representing extremes of dietary restraint, factor analysis of the results and questionnaire revision. Three stable factors emerged: (1) 'cognitive restraint of eating', (2) 'disinhibition' and (3) 'hunger'. The new 51-item questionnaire measuring these factors is presented.
Article
Changes in the micro-structure of meals were studied in ten human subjects under different palatability and deprivation conditions. The oscillographic recording of chewing and swallowing movements during standardized meals allowed many meal parameters to be precisely measured. Both increases in deprivation time (from 4 to 15 h) and in food preference produce larger, longer meals. These factor's effects were additive. Eating rate was accelerated in high relative to low preference conditions. The micro-structure of meals proved to be more sensitive to food preferences than to deprivation levels: chewing activity per standard food piece tended to decrease as preference increased, as observed in a previous study. However, in the first quarter of meals, chewing time was affected similarly by deprivation and by preference. A clear deceleration of eating rate was apparent between the beginning and the end of meals. The results are discussed in perspective with other human studies and with reference to preference and deprivation as continua.
Article
This study investigated the effects of palatability on ratings of hunger and other states, food preferences, bodily sensations, feelings and moods. Assessments of these were made before, during and after 12 healthy female subjects ate small equicaloric meals of either highly preferred of less preferred food. The sight of highly preferred food markedly increased subjects' rated desire to eat and this elevation was maintained during consumption. Hunger ratings were also elevated but only during consumption of the highly preferred food and to a smaller extent. There was no effect of the palatability of the food on rated feelings of fullness. Two hours after the meal, ratings of desire to eat and hunger were significantly higher after consumption of highly preferred food. This effect did not occur after eating less preferred food. Feelings of general positive affect, which followed the highly preferred meal, did not occur with the less preferred food. These findings throw light on the nature of the rated expression of hunger and on other terms used in describing dispositions to eat.
Article
After one experience with the effects of a disguised augmentation of the starch content of a food eaten early in a meal, there was a decrease in the amount of that food eaten subsequently at meals on a menu that included the same flavours. Starch eaten late in the meal did not establish this suppression of intake of the item having a flavour paired with the extra starch, but did strengthen its subjective satiating effects, i.e., increased the reduction in rated pleasantness that occurs on eating most foods. When taken as snacks, the same starch-augmented foods had a direct satiating effect, similar in size to the satiating effect of believing the food to be high in calories: 20 min after ingesting the starch, both the amounts the consumer wished to eat and the ratings for pleasantness of foods on a separate menu were reliably lower than after the control snack. Associative conditioning of the pleasantness of eating the flavours of snacks augmented with starch also occurred, resulting in a pattern of acquired responses that accounted for the previously observed differentiation of meal sizes: that is, a conditioned decrease in the pleasantness of a starch-associated flavour was observed when that flavour was eaten and tested in relatively replete states, and a conditioned increase in its pleasantness was observed when training and testing were carried out during normal hunger. Thus, at least parts of both the appetite for a food and the satisfaction from it can be learned from experience of the after-effects of the food’s starch contents.
Article
The spontaneous food intake of six normal-weight male volunteers was measured for 24 days while the subjects were inpatients on a metabolic unit. They were fed a palatable diet of conventional foods and were kept unaware that their food intake was being measured. On days 7-18 the caloric content of their diet was covertly reduced by 25% by substituting aspartame-sweetened analogues for all menu items containing sucrose. Subjects did not alter their food intake for 3 days. Then between days 4-6 on the aspartame diet, they increased their intake to compensate for 40% of the missing calories. Food intake stabilized at 85% of baseline and remained the same for the rest of the 12-day dilution period. Subjects did not show a shift in either sweetened or unsweetened food choices while their diet was being diluted. In adjusting for the missing calories, they simply ate more of their customary diet. The replacement of sucrose by aspartame tended to curb the weight gain observed on the baseline diet.
Article
A universal eating monitor has been developed that permits covert continuous weighing of a subject's plate or other food reservoir by means of a concealed electronic balance. By coupling the device with a digital computer, it is possible to record precisely the amount consumed every 3 s throughout a single-course meal consisting of a relatively homogeneous mixture of foods. The monitor have been used to compare total intake, meal duration, initial rate of intake, and deceleration of intake in human subjects ingesting either a solid or liquid version of the same food after 3 or 6 h without food. It was found that the liquid form was eaten faster than the solid form, but that total amounts consumed in each form were not significantly different. These results suggest that when the rate of consumption is controlled by the physical consistency of the food, the amount eaten is not determined by the rate of consumption alone. Further studied are necessary to determine the relative roles of visual cues and interoceptive signals on quantity eaten.
Article
Preloads (250 ml) of 2% or 10% fructose containing 1% soluble fibre and 1% insoluble fibre or 10% fructose with 3% soluble fibre and 1% insoluble were administered 60 min before lunch to 24 healthy women, who were slightly overweight and considerably weight concerned. The fibre consisted of guar gum, partly hydrolysed for the soluble form. The placebo consisted of a solution of sweeteners (cyclamate and saccharin). After the experiment with three preload-types and a placebo, a random subset of 15 subjects returned for an experiment with one preload-type and a placebo, given 30 or 60 min before lunch. Food intake during the subsequent lunch was only significantly different from after the placebo in this subset of 15 subjects after the 10% fructose/3% soluble and 1% insoluble fibre preload after intervals of 30 or 60 min. However, energy intake of preload and meal was significantly higher than energy intake of placebo and meal. At the 30-min delay, eating rate was significantly lower after the preload than after the placebo; also, hunger ratings were lower after intake of a preload and meal than after intake of the placebo+meal, from immediately after lunch until 5 hours later. Energy intake over 24 h was not affected by administration of fructose/fibre or placebo 30 or 60 minutes before lunch in the 24 women.
Article
To investigate whether children acquire conditioned preferences for flavors associated with high dietary fat content, 27 3- and 4-year-old children participated in a series of 12 conditioning or mere exposure sessions. Following an overnight fast, children who participated in conditioning trials consumed fixed quantities of a flavored yogurt drink that on half the days was high in fat and energy (954 kJ, 18 g fat/150 g serving) or contained no fat (277 kJ, 0 g fat/150 g serving). Children in the conditioning group consumed 150 g servings, children in the mere exposure group tasted 16 g or less of these same stimuli. Preferences were assessed before and after conditioning when the children were hungry and also postconditioning when the children were satiated. Results provided evidence for conditioned preferences based on the postingestive consequences of dietary fat. Children in the conditioning group learned to prefer the high-density paired flavor over the low-density paired flavor, and increased their preference for the high-density paired flavor from pre- to postconditioning. Children in the mere exposure group showed positive shifts in preference for both the fat-free and the high-fat paired flavors. In the conditioning group, preferences for the high-fat flavor was depressed by satiety, whereas the preference of the mere exposure group did not vary with hunger state. Conditioned flavor preferences, based on the postingestive consequences of fat intake, may contribute to children's preferences for foods high in dietary fat.
Article
Ten pairs of obese and nonobese monkeys, matched for age and sex, received one liquid test meal a day for 4 days. Testing was conducted during the middle of a 6-h period of food deprivation. At all other times the monkeys were freely fed on maintenance chow biscuits. The first test meal of grape and orange flavor drinks familiarized them with fluids containing an intermediate level of added carbohydrate (CHO) (27.5%); equal volumes of grape and orange flavors were presented. During testing, the positions of the two flavors were switched three times, thus forcing the monkey to make four choices during the meal. On days 2 and 3, four pairs of monkeys received low-energy liquid meals (10% CHO), and six pairs received high-energy meals (45% CHO); half of the pairs in each group had orange flavor, half grape. On day 2, meal volumes did not differ between the 10% and 45% CHO groups; rather, the size of the meal (regardless of CHO composition) correlated with mean daily chow intake. On day 3, the volume consumed of the 10% CHO solution increased and the volume of the 45% CHO solution decreased, generating a difference between groups that indicated one-trial learning of control of meal size. On day 4, each monkey was given a test meal of repeated choices between samples of grape and orange flavor, both containing the intermediate 27.5% CHO.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
This study was done to determine the relative effects of energy content and weight of ingested food on subsequent satiety and food intake. The weight/volume and the energy content of nine preloads were manipulated, in a 3 x 3 factorial design, to give three weight levels, 250, 500 and 750 g, and three energy levels 0, 1.26 and 2.51 MJ (0, 300 and 600 kcal). The weights were varied by the addition of water, while the energy levels were varied by using yogurt and cream. Each of the 1.26 and 2.51 MJ preloads contained 27 g of protein and 31 g of carbohydrates. The 1.26 MJ preloads contained 8 g of fat and the 2.51 MJ preloads had 41 g of fat. Each of the nine preloads was presented as a lunch to 21 female and 16 male subjects. Two hours after the preloads, subjects consumed sweet and savory snacks and various drinks ad libitum from a buffet. The weight of the preload had a small but statistically significant effect on feelings of hunger and satiety between preload and buffet, and on energy intake during the buffet (5.34, 5.05 and 5.04 MJ after 250, 500 and 750 g preloads). There was a large difference between 0 and 1.26 MJ, but little difference in effect between 1.26 and 2.51 MJ preloads. Mean energy intakes in the buffet after the 0, 1.26 and 2.51 MJ preloads were 6.17, 4.83 and 4.42 MJ. These results suggest that the weight or amount of food affects subsequent appetite and food intake, but the effect of energy is stronger.
Article
The effects of manipulated palatability on eating were assessed in 54 human volunteers eating pasta with a tomato sauce, with palatability adjusted by the addition of three levels of oregano. Meals were divided into 2 min eating episodes separated by brief pauses during which subjects rated aspects of appetite. Both intake and eating rate were greatest in the most palatable condition (0.27% oregano), whereas the addition of 0.54% reduced intake and eating rate. Hunger ratings increased during the initial stages of the meal with 0.27% oregano, but fell throughout the meal in the other conditions, whereas fullness ratings increased similarly in all three conditions. Rated food attractiveness was greatest with 0.27% oregano, and least with 0.54% oregano, but declined similarly through the meal with all three foods. Initial ratings of palatability were similar to those for food attractiveness, but changes in palatability across meals varied between subjects. Male subjects consistently ate more and faster than females, but similar effects of manipulated palatability on intake and subjective appetite were seen in both sexes. These data are consistent with the idea that palatability increases intake through a positive-feedback reward mechanism, and offers a novel method for measuring these effects.
Article
The effects of 50 mg naltrexone on eating and subjective appetite were assessed in a double-blind placebo-controlled study with 20 male volunteers. Appetite was monitored using a disguised digital balance connected to a micro-computer, which constantly monitored the amount of food remaining, and which automatically interrupted feeding for 30 s after every 50 g consumed to allow appetite ratings to be made. Half the subjects ate pasta with a cheese sauce, and the remainder pasta with a tomato sauce. Subjects ate significantly less of both foods after 50 mg naltrexone than in either the placebo condition or on the initial (familiarisation) day. Naltrexone also reduced the rated pleasantness of both foods, and reduced overall eating rate. When best-fit quadratic functions were used to describe changes in rated hunger in relation to intake within the meal, naltrexone abolished the positive linear component reflecting the initial stimulation of appetite without altering either intercept or the negative quadratic function. Although mood ratings suggested that naltrexone had a mild sedative effect, mood changes alone could not explain the effects of naltrexone on appetite. Overall, these data suggest a specific role for opioids in the stimulation of appetite through palatability.
Article
The effects of the introduction of timed pauses within meals and palatability on food intake and changes in rated appetite during a meal were assessed in three experiments in which volunteers ate a lunch of pasta with a tomato sauce. Eating was monitored using a disguised electronic balance attached to a micro-computer, which also allowed the introduction of timed pauses within meals. In the first experiment, 16 subjects were tested with both a bland and palatable food (with 0.27% oregano), with eating uninterrupted or with pauses after every 50 g consumed during which appetite ratings were completed. Both the addition of oregano and the introduction of regular within-meal pauses enhanced overall intake. Rated hunger increased in the early stages of eating the palatable food in the interrupted condition, and then declined, whereas hunger declined throughout with the bland food. Similarly, the linear function relating intake to time in the uninterrupted condition was greater with the palatable food. In the second experiment, nine subjects ate the palatable food with no pauses within meals, with 30-second pauses with appetite ratings or with 30-second pauses in a non-appetite task. Intake was greater in both pause conditions than when eating was uninterrupted. In Experiment 3, the effect of pause duration was investigated in a further 16 subjects, with either no pause or a pause of 5, 30 or 60 seconds. Subjects ate more in all pause conditions than with no pauses, while ratings of hunger and fullness suggested that subjects were less satisfied at the end of the meal with longer pauses. These data confirm previous work which suggests that palatability exerts its effect by stimulating appetite and eating rate, but also suggest that the introduction of pauses within meals enhances intake as well, contradicting the idea that pausing within meals should reduce intake by allowing more time for post-ingestive satiety to develop.
Article
This paper introduces a satiety quotient (SQ) to assess the satiating effect of an eating episode. This procedure constitutes an improvement on previous measures by considering the satiating effects of the eating episode over time. A satiety quotient was calculated from data obtained from several studies involving the presentation of a preload/meal to young lean male and female subjects. Subjects were presented with preloads/meals of varying composition, and motivation to eat immediately prior to, and periodically following, the eating episode were measured. Food and fluids were not consumed whilst motivation to eat was measured in the post preload/meal period. The SQ was calculated by dividing the difference between ratings of motivation to eat before and after the eating episode (pre minus post) by the weight or energy content of intake during the episode. This quotient relates intake to the rate of return of motivation to eat in the post-ingestive period, a relationship which is not apparent on separate examination of the amount consumed or ratings of motivation to eat. Development of this satiety quotient is a further contribution to the evolution of the concept of quantifying satiating effects of foods, and provides additional information on the effects of food attributes on short-term appetite control.
Article
The effects of consumption of a soup preload with added maltodextrin, relative to a no-maltodextrin control soup matched for sensory properties, on intake and the pattern of changes in rated hunger and fullness during lunch were investigated in 24 male volunteers. Preloads were consumed 30 min before lunch and condition-order counterbalanced. Intake at lunch was reduced significantly by 77 g (407 kJ) after the maltodextrin preload, and this reduced intake was associated with a significant reduction in eating rate but not meal duration. Hunger ratings were significantly lower, and fullness ratings significantly higher, at the start of lunch after the maltodextrin compared with control preload. However, the pattern of changes in subjective appetite once eating had started (assessed by analyzing best-fit quadratic functions between rated appetite and actual intake) did not differ between preloads. Neither the rated pleasantness of the lunch food at the start of the test meal nor the pattern of change in pleasantness across the meal differed between preloads. These results imply that the effect of maltodextrin preloads on appetite is to reduce the general desire to eat, and possible mechanisms for this effect are discussed.
Article
High energy density tends to be associated with high palatability, and vice versa. As a rule, energy-dense foods are palatable but not satiating, whereas foods with low energy density are more satiating but less palatable. Low-energy-density foods are typically those that contain the most water and the least fat. Reducing energy density while maintaining palatability is a continuing challenge to the food industry.
Article
To investigate the contribution of oral, gastric and intestinal factors in the control of appetitc, 425 ml (400 kcal) tomato soup was administered either orally, intragastrically (covertly and overtly) or intraduodenally (overtly) to nine healthy, fasted, male volunteers. Ratings of fullness, hunger and desire to eat were recorded over a period of 2 h and gastric emptying was measured after soup fed orally and intragastrically. Infusion of the soup into the small intestine at a rate commensurate with normal gastric emptying exerted no significant suppression of ratings of hunger and desire to eat and no significant production of fullness. Covert, intragastric infusion of the same soup suppressed appetite and this suppression was increased when the subjects were informed of the nature of the infusion, but there were no differences in gastric emptying profiles between covert and overt intragastric infusions of soup. Oral administration of the soup produced the greatest suppression of appetite compared with other conditions and also generated a slower rate of gastric emptying compared with both intragastric soup infusions. Strong correlations were observed between appetite ratings and both gastric and intestinal contents following intragastric infusions of the soup meal and these were enhanced following oral administration of soup. These results indicate how information, orosensory, gastric and intestinal factors can interact to elicit optimal expression of fullness and suppression of hunger. Specifically, the data not only demonstrate how the influence of gastric distension appears to overwhelm any direct influence of intestinal chemostimulation on appetite and how information modulates this effect, but the data also support an important role in appetite suppression for psychophysiological mechanisms stimulated by orosensory mechanisms.
Article
Studies have shown that energy intake increases when both the fat content and energy density of the entire diet increases. When the fat content and energy density vary independently of one another, however, energy density, but not fat content, influences intake. The present study examined whether energy intake in lean and obese women is affected when either the energy density or the fat content of a portion of the diet is manipulated and palatability is held constant. In a within-subjects design, 17 lean and 17 obese women consumed meals in the laboratory for four, 4-d test periods. In 3 of these test periods the energy density (4.4 and 6.7 kJ/g) or the fat content (16% and 36% of energy) of compulsory entrees representing 50% of each subject's usual energy intake was manipulated. Additional self-selected foods were consumed ad libitum at meals and as snacks. There were no systematic differences in palatability of the manipulated foods across conditions. Obese and lean participants responded similarly to the dietary manipulations. Intake of self-selected foods at meals was reduced significantly by 16% for both lean and obese subjects in the low- compared with the high-energy-density condition. The fat content of the compulsory foods had no significant effect on energy intake. Ratings of hunger did not differ between diets. These results indicate that when a portion of the diet was manipulated, the energy density, but not the fat content, of the foods affected total energy intake at meals in both lean and obese women.
Article
The present study was designed to investigate the effect of the pleasantness of a food on satiation (meal termination) and satiety. It was also studied whether or not the subsequent availability of other attractive foods affected the effect of palatability on intake. In a within-subjects repeated-measures design, 35 (26 female and 9 male) young healthy nonrestrained subjects consumed at lunchtime a preload consisting of tomato soup, and a buffet/test meal consisting of many attractive food items. Three factors were manipulated. The palatability of the preload was manipulated by varying the citric acid concentration of the soup at three levels: 0 (pleasant), 7.5 (less pleasant), and 15 (unpleasant) g citric acid/kg soup. Intake of the soup was either ad lib (for investigation of satiation), or standardized (350 g for women, and 500 g for men; for investigation of satiety). The third factor was the availability of other foods, manipulated by the amount of time between start of preload and start of the test meal (intermeal interval = IMI), which was set at two levels: 15 and 90 min. Subjects rated hunger and satiety feelings, before the preload, and in between preload and test meal. The results showed that the ad lib intakes of the less pleasant and unpleasant soups were about 65 and 40% of the intake of the pleasant soup. Subjects ingested about 20% more soup when the subjects had to wait for the test meal about 90 min, compared to the 15 min IMI condition. The availability of other foods had no effect on the effect of pleasantness on ad lib intake. There was also no effect of the pleasantness on subsequent satiety: hunger ratings and test meal intake were similar after the three standardized soups. One conclusion is that pleasantness of foods has an effect on satiation but not on subsequent satiety. A second conclusion is that people eat more of a food when they know that they have no access to other foods for a particular amount of time.
Article
Detailed analysis of the pattern of change in rated appetite within a meal have proved a useful technique through which to explore appetite control. Variability in individual ratings, and technical difficulties in achieving ratings at equivalent stages of a meal, have lead to the use of curve-fitting techniques to model changes in rated appetite across a meal. These changes could best be described by a quadratic function, in which the three parameters (intercept, linear and quadratic coefficients) represented distinct influences on meal size. In normal subjects, manipulations of palatability and opioid receptor blockade and preloads of alcohol all modified the linear component of this function only, while preloading with maltodextrin reduced appetite at the start of eating (the intercept) but not the pattern of change in ratings within that meal. Thus the linear coefficient appears to measure the degree of stimulation of appetite by the sensory characteristics of the food, while the intercept reflects baseline appetite at the start of a meal. These results suggest that microstructural analyses of rating changes allow some dissociation of the factors underlying motivation to eat, and provide a novel methodology for future experimentation.
Article
To investigate palatability influences on the ad lib eating behavior of free-living humans, 54 French participants were paid to maintain food intake diaries for four 7-day periods. They recorded their intake along with palatability ratings, on a seven-point scale, of each individual item eaten and also a global rating of the palatability of the entire meal. Higher levels of palatability were found to be related to larger meal sizes, durations, and deprivation ratios, smaller satiety ratios, greater hunger, and lower depression and anxiety. The global palatability rating was found to be superior to individual item palatability ratings as a measure of the palatability of the meal. Although palatability was found to have fairly large effects on intake, it accounted for less than 2% of the variance. It was concluded that, in the natural environment, there are a large number of other powerful variables present that add variance. In addition, people tend to self-select only a restricted range of highly palatable foods. As a result, in the natural environment, the influence of palatability on intake is limited.