Variety enhances food intake in humans: Role of sensory-specific satiety
L. Brondela,⁎, M. Romera,b, V. Van Wymelbekea, N. Pineaua, T. Jianga, C. Hanusa, D. Rigauda
aCentre Européen des Sciences du Goût, UMR CNRS 5170, Dijon, France
bDepartment of Clinical Neurology, Vienna, Austria
a b s t r a c ta r t i c l ei n f o
Received 14 January 2009
Accepted 27 January 2009
Twenty-one subjects were studied to evaluate the effect of renewal of sensory stimulations of previously
eaten foods on sensory-specific satiety and intake. The subjects ate French fries then brownie cakes ad
libitum in three situations: “monotonous” — fries then brownies were consumed alone; “simultaneous” —
condiments (ketchup and mayonnaise for the fries, vanilla cream and whipped cream for the brownies) were
added during intakes; “successive” — after intake of fries alone, ketchup then mayonnaise were available
with fries and, after intake of brownies alone, vanilla cream then whipped creamwere offered with brownies.
The quantities eaten in the “simultaneous” and “successive” situations were higher (pb0.001) than those in
the “monotonous” one (1485±582 and 1682±777 kcal vs 1195±552 kcal, respectively). In the “successive”
situation, hedonic ratings for fries diminished during intake but increased after the introduction of ketchup,
leading to additional intake of fries. Similarly, hedonic ratings for brownies diminished during intake and
increased after the introduction of vanilla cream leading to additional brownie intake (mayonnaise and
whipped cream had no significant effect). Food variety, obtained by adding condiments can increase food
intake in the short term. The mechanism by which food consumption is increased after the addition of
condiments is introduced is at least partly related to the attenuation of sensory-satiety for a given food.
© 2009 Elsevier Inc. All rights reserved.
Obesity is increasing world-wide , especially in western nations
. The reasons leading to the imbalance between energy intake and
energy expenditure are multifactorial . Among the different factors,
food variety could play a role [4–7]. Actually, several animal studies
have shown that variety increases food intake and leads to body-
weight gain [8,9]. It has also been observed in normal-weight humans
that food variety may stimulate food intake in the short term [10–14].
It is not clearhow varietystimulates food-intake. Fromonepointof
view, variety may increase intake by an appetite-stimulating mechan-
ism. This could be due to renewed palatability (i.e. the ‘liking’ or
pleasantness of food) in relation to the diversity of the eaten foods
[15,16], by sustaining interest in eating , by another stimulating
mechanism involving metabolic and hormonal responses, or environ-
mental, psychological and social variables [6,18]. From another point
of view, food variety may increase intake by delaying satiation (i.e.
meal termination). This could be related to a decrease in sensory-
specific satiety  or by a dishabituation mechanism  induced by
Sensory-specific satiety (SSS) is a satiation mechanism defined as
the decline in pleasantness of the flavour of a specific food that has
just been eaten in contrast to other non-consumed foods [20,21]. The
decrease in pleasantness linked to SSS is observed very rapidly, 2 min
after the end of ad libitum intake, before food enters the intestinal
tract and before intestinal absorption [22,23]. The implication of SSS
on elevated food intake associated with varied meals has been known
for a long time. Actually, as sensory-specific satiety is specific for eaten
foods, when a great variety of foods is available during a meal, it may
take longer for satiation to occur for all foods, which leads to greater
Although the link between high consumption of varied meals and
sensory-specific satiety is well established, several researchers
stressed that this link needs to be strengthened. McCrory et al. 
wrote, ‘although the mechanism by which a drive for dietary variety
gets translated into increased food consumption is not known, the
phenomenon of sensory-specific satiety is a probable candidate’.
Similarly, Raynor and Epstein  wrote that ‘sensory-specific satiety
may be the process through which a greater variety of food is
associated with increased intake’ and, Norton et al.  argued that ‘a
potential mechanism underlying the variety effect may be due to the
increased stimulation associated with multiple foods delaying the
development of sensory-specific satiety’. Furthermore, to our knowl-
edge, neither the temporal evolution of hedonic sensations for a
varietyof foods offered successivelyand simultaneously (i.e. change in
SSS) , nor the effect of introducing of a new flavour in a previously
eaten food have been reported in fundamental experiments.
The present experiment was conducted to bring new arguments to
the relationship between SSS and the high food-consumption during
intake of a varied meal as well as to study how small amounts of
Physiology & Behavior 97 (2009) 44–51
⁎ Corresponding author. Centre Européen des Sciences du Goût, 15 rue Hugues
Picardet, 21000 Dijon Cedex, France. Tel.: +33 3 80 68 16 77.
E-mail address: email@example.com (L. Brondel).
0031-9384/$ – see front matter © 2009 Elsevier Inc. All rights reserved.
Contents lists available at ScienceDirect
Physiology & Behavior
journal homepage: www.elsevier.com/locate/phb
variability may disrupt SSS. More precisely, the study set out to
determine whether modification of the sensory properties of a food
eaten ad libitum by adding condiments could decrease sensory satiety
for that food and subsequently lead to additional intake of that food. A
within-subject design was created to rate relative preference-changes
of an ad libitum two-course meal in either a monotonous form or with
simultaneous or successive variety via the addition of condiments.
The meal was of the ‘fast-food’ type since it has been suggested that
this type of meal could play a role in the prevalence of obesity .
2. Subjects and methods
The participants were 21 male volunteers (age: 22±3 yr, range
18–28; BMI: 22.4±0.9 kg m−2, range 21.0–24.2), who gave written
consent to participate in the experiment. All participants were
students at the University of Dijon (Burgundy). Female subjects
were not retained because of hormonal variations during their
menstrual cycle and for their potential higher cognitive control of
eating . The ethical committee of the University Hospital of
Besançon (France) approved the protocol.
activity (less than 5 h/week) and non-smoking habits. Exclusion
criteria were eating disorders (evaluated by questionnaire during the
medical check up and by stability of body-weight from the 2–3
preceding years), dieting or fasting, food-snacking (more than
two intakes during daytime in addition to the 3 traditional French
Before the experiment, the Three Factor Eating Questionnaire 
was filled in. Participants had mean three-factor eating questionnaire
scores of ‘cognitive restriction of eating’=5.5±2.7, ‘eating disinhibi-
tion’=5.1±2.7 and ‘susceptibility to hunger’=4.8±3.0. Two sub-
jects were restricted eaters (scores of ‘cognitive restriction of eating’
≥9), but neither were disinhibited orhungry. Prior to the sessions, the
participants were not informed about the aims of the experiment, the
meal-structure or the measurements made. The subjects were tested
individually in a dining room of the laboratory. Theywereadvised that
they could retire their participation at any time without having to
2.2. Sessions and foods eaten
Three randomized sessions were held on three consecutive weeks
(one sessionper week). The sessions consisted in a 2-course meal: the
1st course consisted of lightly salted fries (with or without
condiments); the 2nd course of brownie cakes (with or without
In the “monotonous” session, the two courses, fries and brownies,
were offered without condiments and each was eaten ad libitum. In
the “successive” session, fries were first offered without condiments,
then fries with one of the condiments, and finally fries with the other
condiment were offered (the order of condiment presentation was
randomized). Each condiment was presented by the experimenter
immediately after the subject ceased intake of the preceding food
which was ad libitum (fries and condiments). The same procedurewas
repeated with brownie cakes in the 2nd course (brownies alone then
brownies with one condiment then brownies with the other
condiment, with the order of condiment presentation randomized).
In the “simultaneous” session, both condiments were freely available
during the whole of each course which was also eaten ad libitum.
Because a pilot session on 15 subjects had shown that spontaneous
intakes of the foods lasted less than 35 and 15 min for the two courses,
respectively, maximum durations of intake were limited to 35 min for
the 1st course and to15 min for the 2nd course. If participants finished
intake of the 1st course in less than 35 min, they had to wait until
minute 35. To avoid the effects of portion size on intake, the fries and
brownies were served in successive small portions on a plate (a new
portion was offered every time the plate was finished). Portions for
fries and brownies were approximately 100–120 g and 80–100 g,
respectively. Condiments were offered in quantities of about 30 g in
small separate cups. Energy contents of the foods (per 100 g) were:
fries: 1147 kJ (274 kcal); tomato ketchup: 414 kJ (99 kcal);
mayonnaise: 2771 kJ (662 kcal); brownie cakes: 1968 kJ (470 kcal);
vanilla cream: 523 kJ (125 kcal); whipped cream: 921 kJ (220 kcal). In
the pilot session, palatability for fries and for fries with condiments
was evaluated on a 100 mm visual analogue scale with the question:
“How good does this taste?” (the scale ranged from “very unplea-
sant”=−5 to “very pleasant”=+5). Palatability of the foods was for
fries: 0.3±1.5 (median 0.3); for fries with tomato ketchup: 1.4±1.9
(median 1.9); for fries with mayonnaise: 0.4±2.5 (median 1.4).
Thesameinvestigator,whoremainedin theroom, served thefoods
and recorded the data (time, weighting, and subjective ratings).
During intake, each participant had free access to 250 ml of tap water.
2.3. General procedure
Before each session, participants had to take their usual breakfast
at home and to fast during the 4 h preceding the experiment (only
water, notea or coffee, were allowed). Starting time was 11:00 a.m. for
11 subjects and 12:30 p.m. for 10 subjects.
After rating their pre-prandial hunger, the temporal sequence was
as follows (Fig. 1): 1st olfactory evaluation (at t−5); ad libitum intake
of the 1st course with Flavour–Pleasure evaluation for the consumed
foods and reasons for stopping eating (from t0to t35); 2nd olfactory
evaluation (at t35); ad libitum intake of the 2nd course with Flavour–
Pleasure evaluation for the consumed foods and reasons for stopping
eating (from t40to t55); 3rd olfactory evaluation (at t55).
Postprandial hunger was evaluated 5 min after the meal. To
confirm subjects' satiation, a buffet was offered 10 to 15 min after
finishing the meal. Subjects were uninformed about this buffet and
invited to eat whatever they wanted out of 16 different foods.
Subjective ratings (hunger, olfactory evaluations and Flavour–
Pleasure ratings)wereevaluated using100 mmvisualanaloguescales.
Hunger was assessed by the question: “How hungry do you feel at
this moment?” The scalewas anchored with “none” and “very high” at
tomato, mayonnaise, and tomato ketchup) were presented in a
random order. Each item was served in a separate cup and smelt
orthonasally for about 10 s at 10–15 cm from the nose. For each item,
questions were: “Could you estimate the pleasure you feel when you
smell the food?” and “Is your mouth watering?” The scales for
Olfactory Pleasure ranged from “very unpleasant” to “very pleasant”;
the scale for Stimulus-induced Salivation from “none” to “very high”.
Flavour–Pleasure for the consumed foods (i.e. pleasantness of the
food following tasting) was evaluated for the 1st mouthful, then every
2 min until the last mouthful of food and immediately when the
subjects said they did not want to eat more of the offered foods. The
question was: “How good does it taste?” The scale ranged from “very
unpleasant” to “very pleasant”.
After stopping eating either course, subjects were also asked to
choose three out of a list of ten predetermined reasons for stopping
eating and to rank them by their order of importance.
Food consumptionwas established every 2 min by weighing initial
and final foods separately using three digital balances accurate to 1 g
(ScoutProSPU 401; max.weight:400 g;d=0.1 g). Food energyintake
L. Brondel et al. / Physiology & Behavior 97 (2009) 44–51
was then computed using Bilnut 4.0 software (S.C.D.A. Nutrisoft, 37390
Cerelles, France). Spontaneous durations of intake of each main course
Finally, the freely consumed quantity (g) of each food from the
buffet was measured and energy intake calculated with Bilnut
2.5. Statistical analyses
Values are expressed as means±SD. Data on Flavour–Pleasure are
analyzed in 4 different ways as: i) the absolute value, ii) the values at
the beginning, a quarter of theway, half way, threequartersof theway
through the meal and at the end of intake because as it was ad libitum,
the duration of the spontaneous intake varied from one individual/
session to another, iii) the change in hedonic ratings between the
beginning and the end of intake (delta rating), iv) the change in
hedonic ratings per gram of consumed foods. The evolution of
subjective ratings in each situation, as well as the differences among
the experimental sessions, was analyzed using one-way repeated
were observed, Tukey' post-hoc test was applied to isolate the group
differing from the others. Spearman's correlation test was performed
to screen for links between data. Analyses were conducted using
SigmaStat software (version 3.1, Systat Software Inc., Richmond,
3.1. Food intake and Flavour–Pleasure ratings
Ingested quantities and durations of intake differed according to the
was 40%and35% higher(F(2,40)=12.75,pb0.001) inthesuccessive and
simultaneous sessions, respectively, than in the monotonous one. In the
successive session, mean intake of fries eaten alone was 270±128 g,
fries eaten with tomato ketchup 27±27 g, and fries eaten with
mayonnaise 22±26 g (i.e. 740±341, 74±74, and 60±71 kcal, respec-
tively); mean intake of brownies eaten alone was 119±71 g, brownies
eaten with vanilla cream 24±25 g, and brownies eaten with whipped
cream 15±20 g (i.e. 559±334,113±117, and 70±94 kcal, respectively).
The weights of condiments consumed compared to the total intake were
8% in the successive session and 19% in the simultaneous one.
The mean total energy intake was 41% and 24% greater (F(2,40)=
11.93, pb0.001) and the mean duration of intake was 21% and 17%
higher (F(2,40)=3.61, pb0.05) in the successive and simultaneous
sessions than in the monotonous one. There was no significant
difference in water intake for the 3 sessions.
Ingested food weight, energy intake and duration of intake in the three sessions.
French friesTomato ketchup MayonnaiseBrownies Vanilla creamWhipped cream Total intake
Ingested food weight (g)
Energy intake (kcal)
Duration of intake (min)
Values are mean±SD.aanda′: pb0.001 and pb0.05 respectively, between the monotonous and the successive sessions;bandb′: pb0.001 and pb0.05 respectively, between the
monotonous and the simultaneous sessions;c: pb0.01 between the successive and the simultaneous sessions.
Fig.1. Timing of the experiment:In the three sessions (monotonous, successive and simultaneous), the followingparameters wereevaluated by visual analogue scales: hungerbefore
and after intake; Olfactory Pleasure (OP) and Stimulus-induced Salivation (SIS) for eight foods during olfactory evaluation; Flavour–Pleasure (FP) for fries and brownies and Reasons
for Stopping Eating (RSE), during and after intake. Time (t) in min.
L. Brondel et al. / Physiology & Behavior 97 (2009) 44–51
The energy content of foods freely consumed during the buffet
(which was presented to confirm subjects' satiation after the two
courses) did not differ (F(2,40)=2.51, p=0.09) among the three
sessions (monotonous: 93±132 kcal; successive: 56±91 kcal;
simultaneous: 66±109 kcal).
Evolution of Flavour–Pleasure is shown in Fig. 2. In the monotonous
session, Flavour–Pleasure for fries decreased after ad libitum ingestion
(F(4,80)=24.32, pb0.001), as did that for brownies after ad libitum
intake (F(4,80)=24.94, pb0.001). In the successive session, Flavour–
21.08, pb0.001), but the subsequent presentation of tomato ketchup
increased Flavour–Pleasure for fries (F(1,20)=8.11, pb0.01), and
was accompanied by the resumption of intake of fries. The
presentation of Mayonnaise had no significant effect on Flavour–
Pleasure and intake. Similarly, Flavour–Pleasure for brownies
decreased during intake (F(4,80)=34.14, pb0.001), but the sub-
sequent presentation of vanilla cream increased Flavour–Pleasure
for brownies (F(1,19)=12.83, pb0.01) and triggered resumption of
intake of brownies. The presentation of whipped cream had neither
an enhancing effect on pleasure nor on intake. In the simultaneous
session, the decrease in Flavour–Pleasure for fries plus tomato ketchup
and mayonnaise (F(4,80)=33.23, pb0.001) and for brownies plus
vanilla cream and whipped cream (F(4,80)=15.73, pb0.001) was
very similar to that in the successive session. Finally, the changes in
Flavour–Pleasure for fries per gram of the ingested food during the
1st course and for brownies per gram of the ingested food during the
2nd course did not differ between the three sessions.
3.2. Correlations between Flavour–Pleasure and ingested quantities
In the three sessions, initial Flavour–Pleasure for fries (at t0) did
not correlate with ingested quantity and duration of intake of fries
when eaten subsequently. In the same way, Flavour–Pleasure for
brownies (at t40) did not correlate with ingested quantities and
duration of intake of brownies when eaten subsequently, a part in the
successive session (Flavour–Pleasure, r=0.604, pb0.01 and duration
of intake, r=0.434, pb0.05). In contrast, the increase in Flavour–
Pleasure from before to after the presentation of tomato ketchup and
mayonnaise in the successive session (delta pleasure) correlated with
the subsequent intake of fries (g and kcal: r=0.557, pb0.01) and the
duration of intake (r=0.482, pb0.01). In the same way, the increase
in Flavour–Pleasure for brownies from before to after the presentation
of vanilla cream and whipped cream (delta pleasure) correlated with
the subsequent ingestion of brownies (g and kcal: r=0.461, pb0.01),
as well as with the duration of intake (r=0.373, pb0.05).
3.3. Olfactory evaluations
As shown in Fig. 3, after ingestion of the fries (between t0and t35), i)
Olfactory Pleasure for fries and mayonnaise decreased in a similar way
in the three sessions (F(1,40)=82.30 and F(1,40)=22.92 respectively,
pb0.001), ii) Olfactory Pleasure for tomato ketchup, tomato and ham
decreased only in the sessions when fries were eaten with tomato
ketchup (F(1,40)=12.40, F(1,40)=6.45 and F(1,40)=13.19, respec-
tively, pb0.01), iii) Olfactory Pleasure for brownies, vanilla cream and
banana did not change. For all eight foods, changes in Stimulus-induced
Salivation from before to after ingestion of fries correlated (pb0.01)
After ingestion of the brownies (between t40and t55), i) Olfactory
Pleasure for brownies decreased in all three sessions (F(1,40)=30.70,
pb0.001), ii) Olfactory Pleasure for vanilla cream decreased only in
the two sessions when vanilla cream was eaten (F(1,40)=23.25,
pb0.001, pb0.05), iii) Olfactory Pleasure for tomato ketchup and
tomato continued to decrease in the three sessions (F(1,40)=23.45
and F(1,40)=27.83 respectively, pb0.001) in particular in the
sessions when tomato ketchup was eaten previously (tomato ketchup:
F(2,40)=7.96, pb0.001; tomato: F(2,40)=11.02, pb0.001), iv)
Olfactory Pleasure for fries decreased in the monotonous session
(F(1,40)=11.61, pb0.01), for mayonnaise and banana in the
simultaneous session (F(1,40)=7.27 and F(1,40)=6.77 respec-
tively, pb0.05) and for ham in the monotonous and in the
simultaneous sessions (F(1,40)=15.65, pb0.001). Changes in
Stimulus-induced Salivation for the eight foods from before to
after ingestion of brownies correlated (pb0.01) with the corresponding
changes in Olfactory Pleasure apart from that for fries, which did not
(data not shown).
3.4. Hunger ratings and reasons for stopping eating
There was no difference in initial hunger (monotonous: 71±15;
successive: 64±18; simultaneous: 68±20) nor in final hunger
(monotonous: 15±14; successive: 16±26; simultaneous: 15±49).
The drop in hunger from before to after final intake (F(1,40)=190.07,
pb0.001) did not differ among the three sessions.
The three predetermined reasons for stopping eating the 1st
coursewere thesamein all three sessions.Themost frequentlychosen
reasons were “I got tired of the food” (25%), “no more hunger” (17%),
“mouth/tongue dryness” (15%), “taste less tasty than initially” (15%),
and “stomach full” (12%). Similarly, no difference in predetermined
reasons for stopping intake in the 2nd course was observed between
the three sessions with “no more hunger” (28%), “stomach full” (20%),
“I got tired of the food” (20%), “mouth/tongue dryness” (12%) and
“tastes less tasty than initially” (12%).
Fig. 2. Time course evolution of the Flavour–Pleasure (in mm) in the three sessions:
monotonous, successive, and simultaneous (high, medium and low part of the figure,
respectively). ⁎⁎ indicates significant Flavour–Pleasure increases (pb0.01) after presenta-
tion of tomato ketchup (K) and vanilla cream (V); ns indicates non significant changes in
Flavour–Pleasure after presentation of mayonnaise (M) and whipped cream (W).
L. Brondel et al. / Physiology & Behavior 97 (2009) 44–51
3.5. Order effect of the sessions
There was an order effect on intake between the three sessions:
5.01, pb0.05) and less brownies during the third time (F(2,40)=4.23,
pb0.05) [weight of fries eaten (g): 1st time 253±124, 2nd time 318±
2nd time 137±732, 3rd time 93±60]. In contrast, there was neither
an order effect for fries with brownies, nor for initial and final
Flavour–Pleasure for both courses. There wasalso noorder effect on the
foods freely consumed during the buffet to confirm subjects' satiation
[weight (g): 1st time 48±50, 2nd time 42±61, 3rd time 38±47;
energy (kcal): 1st time 82±120, 2nd time 62±94, 3rd time 71±121].
The present study confirms the stimulating effects of food variety
on food intake in normal-weight adults in the short term [10–14]. In
both the simultaneous and successive sessions, in which condiments
were offered, food intake at lunch increased in comparison with the
“monotonous” session. This increase in food consumption was similar
(25% to 40%) to that usually reported in the literature on food variety
in humans [6,17,24]. Above all, in the “successive” session, the
decrease in Flavour–Pleasure after the ad libitum ingestion of fries
and brownies was partially reversible by adding tomato ketchup and
vanilla cream, respectively. This increase in hedonic ratings (i.e. delta
rating from before to after the condiment introduction) correlated
withthesubsequentconsumptionofeach of thetwofoodsandled to a
total intake (weight, calories and duration) similar to that observed in
the simultaneous session.
The lower energy intake in the monotonous session in compar-
ison with the two varied ones cannot be attributed to lower hunger
or reduced preference for fries and brownies when eaten alone,
because subjects had similar hunger and similar high palatability for
all the eaten foods before ingestion (i.e. high initial Olfactory– and
Flavour–Pleasure). In the same way, the lower intake in the
monotonous session cannot be related to a difference in hunger
after ingestion since, hunger after intake was similar in all three
sessions, quantities freely consumed during the buffet after the two
courses were very low and similar for the three sessions and,
predetermined reasons for stopping intake did not differ among the
sessions. These results indicate that, in spite of the lower intake in
the monotonous session, different intakes nevertheless produced
similar indicators of satiation. As in the present observation, similar
indicators of satiation after the ingestion of meals differing inweight
and volume [30,31], in particular in experiments studying the
influence of food portion sizes [32–34], have previously been
observed. Furthermore, it seems that in all experiments comparing
ad libitum intake of a variety of foods with ad libitum intake of a
single food, variety increased intake even though there was no
difference in final hunger ratings [14,35–37].
The decline in Olfactory–Pleasure observed from the beginning to
the end of ingestions were primarily food-specific (apart from a
decrease in Olfactory Pleasure for mayonnaise after intake of fries in
the monotonous session; and a decrease in Olfactory Pleasure for ham
and banana after intake of fries and brownies, respectively, in the two
Fig. 3. Olfactory pleasure (in mm) for eight foods during the three olfactoryevaluations (before, between and after the two courses) in the three sessions. ⁎ and ⁎⁎ indicate significant
differences (pb0.05 and pb0.01, respectively) between two evaluations of the same food item.
L. Brondel et al. / Physiology & Behavior 97 (2009) 44–51
varied sessions). The decline in Flavour–Pleasure was noted at the end
of each food eaten when subjects ceased eating (Flavour–Pleasure
could not be evaluated with non eaten foods in order not to
dishabituate the subjects as it was the case with the condiments).
Thesehedoniccharacteristics (food specificityandtemporalpatternof
hedonic decline) correspond to SSS as described by Le Magnen in rats
, and by Rolls et al. in humans . SSS does not require food to
enter the gastrointestinal tract, and is independent of the ingestion of
calories . In contrast, such hedonic variations do not seem to be
attributed to negative alimentary alliesthesia described by Cabanac
, which develops more slowly (its onset is only 15–20 min after
intake), after modification of the internal milieu, and above all which
is not reversible in the very short term after ingestion of similar
In the “successive” session, the increase in hedonic ratings after ad
libitum intake of fries and brownies by adding tomato ketchup and
vanilla cream, respectively, could be attributed to a partial disruption
of sensorysatiety for the food previouslyeaten (i.e. an “attenuation” of
SSS). This attenuation of sensory satiety by the introduction of new
flavours correlated with the subsequent ingestion of fries and
brownies and thus explained the additional consumption of both
foods. Suchattenuationin sensorysatiety is consistent withour recent
observation during which a reduction in SSS was observed after the
introduction of a new flavour or after seasoning a food just eaten .
This is also consistent with observations in rats  and in humans
[17,25,42], where resumption of intake of one food was observed after
presentation of a different food. Recently, Hetherington et al. also
observed that asking participants to taste and rate a different food
while eating one food increased overall intake and delayed the normal
decline in pleasantness and desire to eat that food compared to eating
and rating the same food over time .
The attenuation of sensory satiety and resumption of consumption
was not observed in the successive session after offering mayonnaise
with fries and whipped creamwith brownies. This seems to be related
to an insufficient palatability of the association of the food with the
condiment as shown in Fig. 2. Actually, the palatability of the first
mouthful of fries with mayonnaise had the same hedonic value as the
fries alone at the end of ingestion. Similarly, the palatability of the first
mouthful of brownies with whipped cream had the same hedonic
value as the brownies alone at the end of intake. Of course, others
factors could have also play a role in the non resumption of
consumption (similarity of the sensory properties of the food and
the condiment, unusual consumption of the association of the food
and the condiment, post-ingestive factors and cognitive factors).
In summary, adding condiments to a food just eaten in the
“successive” session was able to attenuate its sensory satiety,
whenever the flavour resulting from the association of the food and
the condiment was palatable.
In the simultaneous session, hedonic ratings for each consumed
food were not evaluated during ingestion in order to avoid interfering
with spontaneous intake. Therefore, SSS-attenuation by adding
condiments could not be evaluated during ingestion. However, as
ingested quantities and duration of intake were similar in the
successive and simultaneous sessions, it is presumable that food
variety by adding condiments attenuated or delayed sensory satiety
foreach eaten food in a similar way tothat in the successive session. In
order to support this hypothesis, it can be noted that the change in
Flavour–Pleasure per gram of fries and per gram of brownies did not
differ between the successive and the simultaneous sessions. More-
over, there is no support for the hypothesis that the subjects were
under pressure to eat more during the successive session because of
the successive presentations of the foods with condiments since
similarintakes were noted in thesuccessiveandsimultaneous session,
during which the investigator did not present successive variations. In
the same way, it cannot be suggested that subjects considered fries
with tomato ketchup or brownies with vanilla cream to be new foods
in the successive session compared to fries or brownies alone, since
subjects ate equal amounts in the simultaneous and in the successive
session (with tomato ketchup, mayonnaise and vanilla cream always
present during respective courses).
The hypothesis that resuming consumption of fries and brownies
by adding condiment could be due to an appetite stimulating
mechanism alone (rather than disruption of the satiation mechanism
such as SSS) is not supported by results of the present study. In fact, in
the successive session, initial hedonic ratings (i.e. palatability) for fries
and brownies did not correlate with subsequently ingested quantities
or duration of intake. This contrasts with the increase in hedonic
ratings after the introduction of condiments (i.e. attenuation in
sensory satiety for the food previouslyeaten) which did. Furthermore,
the higher final FP after ingestion of each course in the simultaneous
session as compared with the successive one indicates that the
decrease inpalatabilitywas not the principalmotivation tostopeating
(if this had been the case, subjects would have continued to eat in the
simultaneous session). At least, attenuation in sensory satiety for the
food previously eaten can be observed only if the association of the
food and the condiment is palatable (as it is observed with tomato
ketchup and vanilla cream but as it is not noted with mayonnaise and
whipped cream). Thus the influence of palatability on intake which is
a classical notion cannot be ruled out [15,43–46].
The mechanism by which sensory satiety is disrupted when
sensory variety (i.e. by offering condiments) is offered remains to be
elucidated. Sensory habituation/dishabituation during ingestion with
no notable modification in sensory perception could play a role
according to research in animals  and humans [48,49]. Such
habituation/dishabituation has been observed in non-human pri-
mates in neurophysiological investigations of feeding [50,51] and in
humans, according to reported hedonic sensations to food
[5,12,37,52,53]. Several arguments may be put forward to support
the habituation/dishabituation hypothesis as an explanation of the
results of the present experiment. First, it has been observed that
sensory habituation/dishabituation mechanisms play a role in
salivary responses and motivated responses to food [35,48,54–56].
In fact, humans habituate to repeated food cues (with a decrease in
the amount of saliva produced) and dishabituate or recover response
(with a return to salivation baseline levels) when a new food cue is
presented. These salivary responses when presenting the same or a
new food are very similar to the hedonic changes observed in the
present experiment. Furthermore, in the present study, changes in
Stimulus-induced Salivation ratings correlated with changes in
hedonic ratings (sensory satiety disruption). Another argument in
favour of habituation when eating the same food and for dish-
abituation when renewing the food's sensory properties relates to the
reasons given by subjects for meal termination. Most frequently,
subjects rated ‘I got tired of the food’ (25%) after eating fries and ‘no
more hunger’ (28%) after eating brownies. These reasons are
consistent with those noted by Hetherington et al. , who reported
that after eating a first course, subjects rated more frequently ‘I got
tired of the food’ (40%) and after eating a second one, ‘I felt full’ (48%).
It thus appears that the sensation ‘getting tired of the food’ which
were most frequently given by subjects before satiety occurred could
reflect a habituation process.
Introducing a new flavour while eating a food as in the varied
sessions in the present experiment could therefore dishabituate a
subject and may consequently explain the higher intake than that
noted in the monotonousmeal. Such interpretations are in accordance
with Temple et al.  who wrote that “habituation theories provide a
general theoretical approach in which any stimulus that alters
attention may disrupt habituation and influence eating, whether the
stimulus involves food cues or audiovisual cues, such as television”.
Habituation/dishabituation mechanisms have been proposed to
explain the potential for food intake to increase when subjects are
distracted [58–64]. Forinstance,it hasbeen shownthat dishabituating
L. Brondel et al. / Physiology & Behavior 97 (2009) 44–51
intake by introducing within-meal pauses increased overall intake in
comparison to continuous intake of the same food . Similarly, it
has been observed that watching television dishabituated eating or
disrupted the development of habituation, which may provide an
explanation for increased energy intake associated with watching TV
[55,66,67]. Dishabituation by the presentation of a new food or after a
new food cue, could as least in part and as suggested by others
[5,12,17,35], mediate the influence of food variety on the increase in
food intake. The intermediate mechanism leading to the recovery of
intake could be a renewal in hedonic ratings (i.e. attenuation of SSS) as
shown in the present experiment.
SSS may have had an important role in food selection and might
have been advantageous during human evolution as it ensured
diversification of food intake in a poor nutritional environment in
order to avoid nutrient deficiency [12,68,69]. Today, the high sensory
variety of foods available in mass-market countries and the renewal of
be in part responsible for over consumption in the short term. This
could be a factor leading to the growingepidemic of obesity [70,71] and
conversely, could explain the effectiveness of monotonous diets
prescribed to obese patients for weight reduction [5,12,72]. Of course,
individual attitudes and preferences for a wide range of food choices
may differ among countries and cultures .
The present experiment shows in humans that food variety,
obtained byadding condiments to foods like in a ‘fast food’-style meal,
can increase food intake in the short term. This increase in food
consumption may stem from disruption of sensory satiety for a given
food by renewal of sensory stimulation. This disruption of sensory
satiety by food variety could play a role in the obesity epidemic in
western countries. This subject warrants further investigation in long-
Special thanks to the English department of the Faculty of
Medicine of Dijon for revision of the English.
 World Health Organization W. Obesity and overweight. URL:http://www.who.
 Rubenstein AH. Obesity: a modern epidemic. Trans Am Clin Climatol Assoc
 Finkelstein EA, Ruhm CJ, Kosa KM. Economic causes and consequences of obesity.
Annu Rev Public Health 2005;26:239–57.
 Rolls BJ, Hetherington MM. The role of variety in eating and body weight
regulation. In: Shepherd R, editor. Handbook of the psychophysiology of human
eating. New York: Wiley, J; 1989. p. 57–84.
 RaynorHA, Epstein LH. Dietary variety,energy regulation, and obesity. Psychol Bull
 McCrory MA, Suen VM, Roberts SB. Biobehavioral influences on energy intake and
adult weight gain. J Nutr 2002;132:3830S–4S.
 Kennedy E. Dietary diversity, diet quality, and body weight regulation. Nutrition
 Rolls BJ, Van Duijvenvoorde PM, Rowe EA. Variety in the diet enhances intake in a
meal and contributes to the development of obesity in the rat. Physiol Behav
 Louis-Sylvestre J, Giachetti I, Le Magnen J. Sensory versus dietary factors in
cafeteria-induced overweight. Physiol Behav 1984;32:901–5.
 Bellisle F, Le Magnen J. The structure of meals in humans: eating and drinking
patterns in lean and obese subjects. Physiol Behav 1981;27:649–58.
 Rolls BJ, Rowe EA, Rolls ET, Kingston B, Megson A, Gunary R. Variety in a meal
enhances food intake in man. Physiol Behav 1981;26:215–21.
 Rolls BJ. Experimental analyses of the effects of variety in a meal on human
feeding. Am J Clin Nutr 1985;42:932–9.
 Spiegel TA, Stellar E. Effects of variety on food intake of underweight, normal-
weight and overweight women. Appetite 1990;15:47–61.
 Stubbs RJ, Johnstone AM, Mazlan N, Mbaiwa SE, Ferris S. Effect of altering the
variety of sensorially distinct foods, of the same macronutrient content, on food
intake and body weight in men. Eur J Clin Nutr 2001;55:19–28.
 de Castro JM, Bellisle F, Dalix AM, Pearcey SM. Palatability and intake relationships
in free-living humans. Characterization and independence of influence in North
Americans. Physiol Behav 2000;70::343–350.
 Yeomans MR, Blundell JE, Leshem M. Palatability: response to nutritional need or
need-free stimulation of appetite? Br J Nutr 2004;92(Suppl 1):S3–S14.
 Hetherington MM, Foster R, Newman T, Anderson AS, Norton G. Understanding
variety: tasting different foods delays satiation. Physiol Behav 2006;87:263–71.
 de Castro JM. Eating behavior: lessons from the real world of humans. Nutrition
 Romer M, Lehrner J, Van Wymelbeke V, Jiang T, Deecke L, Brondel L. Does
modification of olfacto-gustatory stimulation diminish sensory-specific satiety in
humans? Physiol Behav 2006;87:469–77.
 Rolls BJ, Rolls ET, Rowe EA, Sweeney K. Sensory specific satiety in man. Physiol
 Rolls BJ. Sensory-specific satiety. Nutr Rev 1986;44:93–101.
 Hetherington MM, Rolls BJ, Burley VJ. The time course of sensory-specific satiety.
 Rolls ET, Rolls JH. Olfactory sensory-specific satiety in humans. Physiol Behav
 Rolls BJ, Van Duijvenvoorde PM, Rolls ET. Pleasantness changes and food intake in
a varied four-course meal. Appetite 1984;5:337–48.
 Cornell CE, Rodin J, Weingarten H. Stimulus-induced eating when satiated. Physiol
 McCrory MA, Fuss PJ, McCallum JE, et al. Dietary variety within food groups:
association with energy intake and body fatness in men and women. Am J Clin
 Norton GN, Anderson AS, Hetherington MM. Volume and variety: relative effects
on food intake. Physiol Behav 2006;87:714–22.
 Pereira MA, Kartashov AI, Ebbeling CB, et al. Fast-food habits, weight gain, and
insulin resistance (the CARDIA study): 15-year prospective analysis. Lancet
 Westenhoefer J. Age and gender dependent profile of food choice. Forum Nutr
 Stunkard AJ, Messick S. The three-factor eating questionnaire to measure dietary
restraint, disinhibition and hunger. J Psychosom Res 1985;29:71–83.
 Blundell JE, Freeman DG. Sensitivity of stimulus-induced-salivation (SIS), hunger
ratings and alliesthesia to a glucose load: SIS as a measure of specific satiation.
 Rolls BJ, Roe LS. Effect of the volume of liquid food infused intragastrically on
satiety in women. Physiol Behav 2002;76:623–31.
 Devitt AA, Mattes RD. Effects of food unit size and energy density on intake in
humans. Appetite 2004;42:213–20.
 KralTV, Rolls BJ. Energy densityand portion size: their independent and combined
effects on energy intake. Physiol Behav 2004;82:131–8.
 Rolls BJ, Roe LS, Meengs JS. Reductions in portion size and energy density of foods
are additive and lead to sustained decreases in energy intake. Am J Clin Nutr
 Wisniewski L, Epstein LH, Caggiula AR. Effect of food change on consumption,
hedonics, and salivation. Physiol Behav 1992;52:21–6.
 Porrini M, Crovetti R, Testolin G, Silva S. Evaluation of satiety sensations and food
intake after different preloads. Appetite 1995;25:17–30.
 Myers Ernst M, Epstein LH. Habituation of responding for food in humans.
 Le Magnen J. [Induction of hyperphagia in white rats by changing the mechanism
of peripheral satiety.]. C R Seances Soc Biol Fil 1956;150:32–5.
 Cabanac M. Physiological role of pleasure. Science 1971;173:1103–7.
 Duclaux R, Feisthauer J, Cabanac M. Effects of a meal on the pleasantness of food
and nonfood odors in man. Physiol Behav 1973;10:1029–33.
 Clifton PG, Burton MJ, Sharp C. Rapid loss of stimulus-specific satiety after
consumption of a second food. Appetite 1987;9:149–56.
 Rolls BJ, Hetherington M, Burley VJ. Sensory stimulation and energy density in the
development of satiety. Physiol Behav 1988;44:727–33.
 Bobroff EM, Kissileff HR. Effects of changes in palatability on food intake and the
cumulative food intake curve in man. Appetite 1986;7:85–96.
 Yeomans MR. Palatability and the micro-structure of feeding in humans: the
appetizer effect. Appetite 1996;27:119–33.
 de Graaf C, de Jong LS, Lambers AC. Palatability affects satiation but not satiety.
Physiol Behav 1999;66:681–8.
 Sorensen LB, Moller P, Flint A, Martens M, Raben A. Effect of sensory perception of
foods on appetite and food intake: a review of studies on humans. Int J Obes Relat
Metab Disord 2003;27:1152–66.
 Swithers SE, Hall WG. Does oral experience terminate ingestion? Appetite
 Epstein LH, Rodefer JS, Wisniewski L, Caggiula AR. Habituation and dishabituation
of human salivary response. Physiol Behav 1992;51:945–50.
 McSweeney FK, Swindell S. General-process theories of motivation revisited: the
role of habituation. Psychological Bulletin 1999;125:437–57.
 Rolls ET. Central nervous mechanisms related to feeding and appetite. Br Med Bull
 Rolls ET. Smell, taste, texture, and temperature multimodal representations in the
brain, and their relevance to the control of appetite. Nutr Rev 2004;62:S193–204
 Hetherington MM, Rolls BJ. Sensory-specfic satiety: theoritical frameworks and
central characteristics. In: Capaldi ED, editor. Why we eat what we eat: the
psychology of eating. Washington, DC: American Psychological Association; 1996.
L. Brondel et al. / Physiology & Behavior 97 (2009) 44–51
 Theunissen MJ, Polet IA, Kroeze JH, Schifferstein HN. Taste adaptation during the Download full-text
eating of sweetened yogurt. Appetite 2000;34:21–7.
 Epstein LH, Paluch RA. Habituation of facial muscle responses to repeated food
stimuli. Appetite 1997;29:213–24.
 Temple JL, Kent KM, Giacomelli AM, Paluch RA, Roemmich JN, Epstein LH.
Habituation and recovery of salivation and motivated responding for food in
children. Appetite 2006;46:280–4.
 Epstein LH, Saad FG, Handley EA, Roemmich JN, Hawk LW, McSweeney FK.
Habituation of salivary and motivated responding for food in children. Appetite
 Hetherington MM. Sensory-specific satiety and its importance in meal termina-
tion. Neurosci Biobehav Rev 1996;20:113–7.
 Ward A, MannT. Don't mind if I do: disinhibited eating under cognitive load. J Pers
Soc Psychol 2000;78:753–63.
 Bellisle F, Dalix AM. Cognitive restraint can be offset by distraction, leading to
increased meal intake in women. Am J Clin Nutr 2001;74:197–200.
 Boon B, Stroebe W, Schut H, Ijntema R. Ironic processes in the eating behaviour of
restrained eaters. Br J Health Psychol 2002;7:1–10.
 Bellisle F, Dalix AM, Slama G. Non food-related environmental stimuli induce
increased meal intake in healthy women: comparison of television viewing versus
listening to a recorded story in laboratory settings. Appetite 2004;43:175–80.
 Mitchell GL, Brunstrom JM. Everyday dietary behaviour and the relationship
between attention and meal size. Appetite 2005;45:344–55.
 Stroebele N, de Castro JM. Listening to music while eating is related to increases in
people's food intake and meal duration. Appetite 2006:285–9.
 BrunstromJM, Mitchell GL. Effects of distractionon the developmentof satiety. Br J
 Yeomans MR, Gray RW, Mitchell GL, True S. Independent effets of palatability and
within-meal pauses on intake and appetite ratings in human volunteers. Appetite
 PoothullilJM. Recognition of oralsensory satisfaction and regulationof the volume
of intake in humans. Nutr Neurosci 2005;8:245–50.
 Temple JL, Giacomelli AM, Kent KM, Roemmich JN, Epstein LH. Televisionwatching
increases motivated responding for food and energy intake in children. Am J Clin
 Rolls ET. Taste, olfactory, and food texture processing in the brain, and the control
of food intake. Physiol Behav 2005;85:45–56.
 Pinel JP, Assanand S, Lehman DR. Hunger, eating, and ill health. Am Psychol
 Levitsky DA. The non-regulation of food intake in humans: hope for reversing the
epidemic of obesity. Physiol Behav 2005;86:623–32.
 de Graaf C. Sensory responses, food intake and obesity. In: Mela D, editor. Food,
diet and obesity. Cambridge, UK: Woodhead publishing Ltd; 2005. p. 137–59.
 Rozin P, Fischler C, Shields C, Masson E. Attitudes towardslarge numbers of choices
in the food domain: a cross-cultural study of five countries in Europe and the USA.
L. Brondel et al. / Physiology & Behavior 97 (2009) 44–51