Kathleen Keller

Pennsylvania State University | Penn State · Department of Nutritional Sciences

It is recommended that preschoolers serve themselves their own food portions; however, it is unclear what factors influence the amount they select for consumption, and particularly how their selected portions are influenced by food properties such as energy density, volume, and weight. We offered preschool children snacks differing in energy densit...

Background: Since children often consume substantial proportions of their diets in childcare programs, it is critical to determine what they eat when served menus meeting dietary recommendations and how intake is related to individual characteristics. Objectives: Using weighed assessments, we characterized children's consumption across 15 daily...

Individuals eat more when served more food, but little is known about how this portion size effect is moderated by meal-related characteristics, particularly the inclusion of water served as a beverage. Patterns of eating and drinking as well as consumption of water could affect satiation by modifying exposure to the sensory qualities of food. In a...

The obesogenic food environment includes easy access to highly-palatable, energy-dense, “ultra-processed” foods that are heavily marketed to consumers; therefore, it is critical to understand the neurocognitive processes the underlie overeating in response to environmental food-cues (e.g., food images, food branding/advertisements). Eating habits a...

Serving larger portions leads to increased food intake, but behavioral factors that influence the magnitude of this portion size effect have not been well characterized. We investigated whether measures of eating microstructure such as eating rate and bite size moderated the portion size effect. We also explored how sensory-specific satiety (SSS; t...

Background When children choose amounts of food to eat, it is unclear what influences the portions they select and whether their selections are related to amounts they consume. Objectives Using a computer survey, we investigated the effect of food liking on portion selection in middle childhood and examined how children's selections related to mea...

The prefrontal cortex (PFC) is a key brain area in considering adaptive regulatory behaviors. This includes regulatory projections to regions of the limbic system such as the amygdala, where the nature of functional connections may confer lower risk for anxiety disorders. The PFC is also associated with behaviors like executive functioning. Inhibit...

Liking plays a primary role in determining what and how much children eat. Despite this, the relationship between liking and intake of foods and beverages served as part of a meal is not often reported, even though pediatric feeding studies frequently collect such data. In addition, few studies have reported on the test-retest reliability of both h...

Appetitive traits that contribute to appetite self-regulation have been shown to relate to non-food-related regulation in general domains of child development. Latent profile analysis (LPA) was used to identify typologies of preschool children's behavioral self-regulation (BSR) and appetitive traits related to appetite self-regulation (ASR), and we...

Longer exclusive breastfeeding duration has been associated with differences in neural development, better satiety responsiveness, and decreased risk for childhood obesity. Given hippocampus sensitivity to diet and potential role in the integration of satiety signals, hippocampus may play a role in these relationships. We conducted a secondary anal...

Increasing childhood obesity rates in both the United States and worldwide demonstrate a need for better prevention and intervention strategies. However, little is understood about what factors influence children's ability to sense and respond to hunger and fullness cues, a critical component of self-regulation of energy intake and maintenance of a...

The prefrontal cortex (PFC) is a key brain area in considering adaptive regulatory behaviors. This includes regulatory projections to regions of the limbic system such as the amygdala, where the nature of functional connections may confer lower risk for anxiety disorders. The PFC is also associated with behaviors like executive functioning. Inhibit...

Food variety, complexity, and portion size each influence food choice and consumption, but their relative importance is poorly understood. In an online discrete choice-experiment, we investigated the relative importance of variety, complexity, and portion size in consumer preferences by systematically varying ice cream offerings. Complexity was def...

Eating in the absence of hunger (EAH), a measure of children's propensity to eat beyond satiety in the presence of highly palatable food, has been associated with childhood obesity and later binge eating behavior. The EAH task is typically conducted in a research laboratory setting, which is resource intensive and lacks ecological validity. Assessi...

Observational coding of children's eating behaviors and meal microstructure (e.g., bites, chews) provides an opportunity to assess complex eating styles that may relate to individual differences in energy intake and weight status. Across studies, however, similar terms are often defined differently, which complicates the interpretation and replicat...

Background Although dietary guidelines recommend that vegetables and fruits make up half the diet, it is unclear whether serving vegetables and fruits in larger portions will have sustained effects on children's intake over multiple days. Objective This study tested the effects on children's intake of 2 strategies for increasing the proportion of...

Decision-making contributes to what and how much we consume, and deficits in decision-making have been associated with increased weight status in children. Nevertheless, the relationships between cognitive and affective processes underlying decision-making (i.e., decision-making processes) and laboratory food intake are unclear. We used data from a...

The Reflective-Impulsive Dual Processes Model suggests that overeating occurs when the temptation to consume food overrides inhibitory control processes. However, how rewards interact with inhibitory control and their relation to children's weight status and food intake is not understood. Here, 7-to-11-year-old children (n = 66; 32 overweight/obese...

Objectives Food liking influences food choice and the most-liked foods are often energy dense. Previous studies found that both food liking and energy density predicted the size of portions selected by adults. To extend these findings, we investigated the independent and combined effects of food liking and energy density on portion selection in chi...

Objectives Although current guidelines recommend that vegetables and fruits make up half the diet, it is not known whether serving a greater proportion of vegetables and fruits will have sustained effects on children's consumption over multiple days. This study tested the effects on children's intake of two strategies for increasing the proportion...

Objectives The relationship between parentally reported satiety responsiveness (i.e., trait) and laboratory-assessed satiety responsiveness (i.e., state) in children is not known, making it difficult to interpret and generalize lab-based findings. In addition, while many studies have shown weight-related differences in children's eating behaviors,...

Objectives Individuals eat more when served larger portions, and this may be influenced by eating-related microstructural behaviors. In a controlled study, we explored whether microstructural components of eating such as eating rate, bite size, bite count, and meal duration influenced the portion size effect. Methods In a randomized crossover desi...

This study investigated the independent and combined effects on preschool children’s vegetable intake of serving a larger portion of vegetables and enhancing their flavor. In a crossover design, lunch was served in childcare centers once a week for four weeks to 67 children aged 3-5 y (26 boys, 41 girls). The meal consisted of two familiar vegetabl...

The relative reinforcing value (RRV) of food measures how hard someone will work for a high-energy-dense (HED) food when an alternative reward is concurrently available. Higher RRV for HED food has been linked to obesity, yet this association has not been examined in low-income preschool-age children. Further, the development of individual differen...

Childhood loss of control (LOC)-eating, the perceived inability to stop or control eating, is associated with increased risk for binge-eating disorder and obesity. However, the correlates of LOC-eating in childhood remain unclear. A secondary analysis of 177, 7-12-year-old children from five laboratory feeding studies was performed to investigate p...

Dark green vegetables (DGVs; e.g., spinach) are a nutrient rich source of essential vitamins and minerals; yet, children’s intakes of DGVs fall well below dietary recommendations and creative solutions are needed. This study describes preschoolers (3-5y) willingness to taste, liking, and intake of fruit-based smoothies containing DGVs (i.e., spinac...

A variety of factors can influence satiation, and individual differences in reasons for meal termination may help to explain variability in food intake and susceptibility to overconsumption. We developed and validated a questionnaire to characterize the Reasons Individuals Stop Eating (RISE-Q). The initial RISE-Q was created by reviewing the publis...

Determinants of food choice are broad and include policies, prices, settings and context, as well as interpersonal factors, such as family, cultural, and peer effects. This review focuses more narrowly on food choices at the individual level by providing an overview of various methods and tools that have been used to understand psychological, cogni...

Vegetable intake is far below recommendations among African-American adolescents living in economically-underserved urban areas. While the National School Lunch Program (NSLP) helps overcome access barriers, vegetable intake remains challenging and novel interventions are required. A two-year, multi-phase, school-based intervention was conducted at...

Interventions designed to improve children's self-regulation of energy intake have yielded mixed results. We tested the efficacy of a technology-enhanced intervention designed to teach children to eat in response to internal hunger and fullness cues. Thirty-two children (mean age 4.9 ± 0.8 y) completed this within-subjects, pre-post design study th...

Food images are routinely used to investigate the cognitive and neurobiological mechanisms of eating behaviors, but there is a lack of standardized image sets for use in children, which limits cross-study comparisons. To address this gap, we developed a set of age-appropriate images that included 30 high-energy-dense (ED) foods (>2.00 kcal/g), 30 l...

Objectives To meet dietary guidelines, effective strategies are needed to encourage children to eat a greater proportion of their diet from vegetables. We tested whether serving a larger portion, enhancing the taste with small amounts of butter and salt, or combining these strategies would increase vegetable intake at a meal for preschool children....

In order to improve dietary quality among children, there is a need to understand how they make decisions about what foods to eat. This study used a mouse tracking food choice task to better understand how attributes such as health and taste contribute to food decisions among 70 children aged 7-to-11 years old. Children rated health, taste, and des...

An “optimal default” refers to a pre-selected default option that promotes an outcome intended to be favorable to the individual and/or society at large. Optimal defaults preserve the decision-maker's ability to opt-out of the default and choose an alternative option. This behavioral economics strategy has been shown to nudge both child and adult c...

Food branding is ubiquitous, however, not all children are equally susceptible to its effects. The objectives of this study were to 1) determine whether food brands evoke differential response than non-food brands in brain areas related to motivation and inhibitory control using blood oxygen level dependent (BOLD) functional magnetic resonance imag...

Greater ability to delay gratification for an immediate food reward may protect against the development of obesity. However, it is not known if the behaviors children exhibit during a delay of gratification task are related to overeating in other contexts. The purpose of this analysis was to assess the relationship between observed child coping str...

Abstract Objective: To test whether adding herbs and spices to school lunch vegetables increases selection and intake compared to lightly salted control versions among rural adolescents. Design: This study compared intake of vegetables with herbs and spices to lightly salted control (phase I) and tested whether 5 repeated exposures would increase...

Background: Although short-term studies have found that serving larger portions of food increases intake in preschool children, it is unknown whether this portion size effect persists over a longer period or whether energy intake is moderated through self-regulation. Objectives: We tested whether the portion size effect is sustained in preschool...

The prevalence of obesity and eating disorders varies by sex, but the extent to which sex influences eating behaviors, especially in childhood, has received less attention. The purpose of this paper is to critically discuss the literature on sex differences in eating behavior in children and present new findings supporting the role of sex in child...

Background and objective: To investigate preschool children's ability to self-regulate their energy intake, we assessed their response to increases or decreases in dietary energy density (ED) over 5 consecutive days, a period likely long enough for compensatory behavior. Methods: Using a crossover design, over 3 periods we served the same 5 dail...

The prevalence of obesity and eating disorders varies by sex, but the extent to which sex influences eating behaviors, especially in childhood, has received less attention. The purpose of this paper is to review the literature on sex differences in eating behavior in children and present new findings supporting the role of sex in child appetitive t...

Objective: We identified factors impacting school lunch vegetable consumption among underserved urban adolescents. Methods: Overall, 26 adolescents completed questionnaires to determine perceptions and preferences of school lunch vegetables and spices/herbs. Sixteen adolescents participated in monadic sequential sensory evaluations to compare taste...

Food commercials promote snack intake and alter food decision-making, yet the influence of exposure to food commercials on subsequent neural processing of food cues and intake at a meal is unclear. This study tested whether exposing children to food or toy commercials altered subsequent brain response to high- and low-energy dense food cues and inf...

Background Brain responses to both food and monetary rewards have been linked to weight gain and obesity in adults, suggesting that general sensitivity to reward contributes to overeating. However, the relationship between brain reward response and body weight in children is unclear. Objective The objective of this study was to assess the brain's...

Exercise may play a role in moderating eating behaviors. The purpose of this study was to examine the effect of an acute bout of exercise on neural responses to visual food stimuli in children ages 8–11 years. We hypothesized that acute exercise would result in reduced activity in reward areas of the brain. Using a randomized cross-over design, 26...

Background Portion size influences intake (i.e. the portion size effect [PSE]), yet determinants of susceptibility to the PSE are unclear. Objective We tested whether children who reported an episode of loss of control (LOC) eating over the last 3 months would be more susceptible to the PSE and would show differential brain responses to food cues...

The reward surfeit model of overeating suggests that heightened brain response to rewards contributes to overeating and subsequent weight gain. However, previous studies have not tested whether brain response to reward is associated with food intake, particularly during childhood, a period of dynamic development in reward and inhibitory control neu...

Figure S1. Perceived intensity of fatty and creamy attributes in safflower oil emulsions with or without added oleic acid in East Asians. Figure S2. Perceived intensity of fatty and creamy attributes in safflower oil emulsions with or without added oleic acid in Caucasians.

Previous studies demonstrate humans can detect fatty acids via specialized sensors on the tongue, such as the CD36 receptor. Genetic variation at the common single nucleotide polymorphism rs1761667 of CD36 has been shown to differentially impact the perception of fatty acids, but comparative data among different ethnic groups are lacking. In a smal...

Background: In this study, we applied behavioral economics to optimize elementary school lunch choices via parent-driven decisions. Specifically, this experiment tested an optimal defaults paradigm, examining whether strategically manipulating the health value of a default menu could be co-opted to improve school-based lunch selections. Methods:...

Objective To test an obesity prevention strategy derived from behavioural economics (optimal defaults plus delay), focused on changing the college dining hall service method. Design After a uniform pre-load, participants attended an experimental lunch in groups randomized to one of three conditions: a nutrient-dense, lower-fat/energy lunch as an o...

Large portions promote intake of energy dense foods (i.e., the portion size effect--PSE), but the neurobiological drivers of this effect are not known. We tested the association between blood oxygen level dependent (BOLD) brain response to food images varied by portion size (PS) and energy density (ED) and children's intake at test-meals of high- a...

American children do not meet the recommended daily servings of vegetables, and previous research suggests children who can taste the bitterness of 6-n-propylthiouracil (PROP) are more likely to have low vegetable intake. This study tested the hypothesis that adding multiple herb and spice blends to vegetables to increase flavor variety within a me...

Purpose: Vegetable consumption in youth is below recommendations and strategies to increase intake at school are needed. We investigated barriers to vegetable intake at a rural public high school and evaluated whether new vegetable recipes using herbs and spices would increase liking and preference for vegetables served to adolescents at this schoo...

Acute exercise has been found to reduce subsequent energy intake in obese adolescents. Although it has been suggested that some neural pathways are involved in this post-exercise energy intake regulation, it remains unknown whether the post-exercise attentional response to food cues differs as a function of weight status. We hypothesize that there...

Background: Several lipid-related hormones and peptides, such as glucagon-like peptide-1 and leptin, are involved in the regulation of taste and smell function. However, to our knowledge, it remains unknown whether these chemosensory functions are associated with lipid profiles. Objective: We examined the cross-sectional association between taste a...

Background: Restrictive feeding is associated with child overweight; however, the majority of studies used parent-report questionnaires. Objectives: The relationship between child adiposity measures and directly observed parent and child behaviours were tested using a novel behavioural coding system (BCS). Methods: Data from 109 children, part...

The US Agricultural Act of 2014 stipulates that the age range for 2020 Dietary Guidelines for Americans expands to include from birth to 24 months. A group of pediatric nutrition researchers and practitioners met to discuss recent data and research gaps, as well as to generate research and potential public-private partnership ideas for future guida...

Optimal defaults is a compelling model from behavioral economics and the psychology of human decision-making, designed to shape or “nudge” choices in a positive direction without fundamentally restricting options. The current study aimed to test the effectiveness of optimal (less obesogenic) defaults and parent empowerment priming on health-based d...

Background: Large portions of food promote intake, but the mechanisms that drive this effect are unclear. Previous neuroimaging studies have identified the brain-reward and decision-making systems that are involved in the response to the energy density (ED) (kilocalories per gram) of foods, but few studies have examined the brain response to the f...

Purpose: To examine the individual-level factors that predict energy intake (EI) following imposed exercise (EX) and sedentary time (SED) in children. Methods: Healthy-weight children ages 9-12 years (n = 20) reported to the laboratory for 1 baseline and 2 experimental visits (EX and SED) each separated by 1 week in a randomized crossover design...

Background Exercise not only has a direct effect on energy balance through energy expenditure (EE), but also has an indirect effect through its impact on energy intake (EI). This study examined the effects of acute exercise on daily ad libitum EI in children at risk for becoming overweight due to family history. Methods Twenty healthy-weight child...

The ability to taste bitter thiourea compounds, such as phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), is inherited. Polymorphisms in the bitter-taste receptor TAS2R38 explain the majority of phenotypic variation in the PROP phenotype. It has been hypothesized that the PROP phenotype is a marker for perception of a variety of chemosenso...

Objective: Large portions of energy-dense foods drive energy intake but the brain mechanisms underlying this effect are not clear. Our main objective was to investigate brain function in response to food images varied by portion size (PS) and energy density (ED) in children using functional magnetic resonance imaging (fMRI). Methods & design: Bl...

We tested the impact of exposure to dolls of different body types and wardrobes on girls' body dissatisfaction. In Study 1, 112 girls (6 to 8 years old) were randomized to one of four conditions: thin (Barbie™) or full-figured (Tracy™) dolls dressed in a swimsuit or modest clothing. In Study 2, a different cohort of girls (n=112) was exposed to one...

Fat discrimination ability varies across individuals and may be related to individual differences in fat preference and dietary behavior. The objective of this study was to develop a brief fat discrimination task using salad dressings varying in canola oil content, in a difference from control format. First, 74 subjects were identified as fat discr...

Previous studies have shown individual differences in the energy intake (EI) response to exercise, but homeostatic or cognitive mechanisms underlying these differences are unclear, particularly in youth. Fat-free mass is a known predictor of daily EI in adolescents and adults, predominantly through its effects on resting metabolic rate and total en...

Determining strategies to decrease energy intake (EI) and promote energy expenditure (EE) is of utmost importance to prevent childhood obesity. Exercise not only has a direct effect on energy balance through EE, but also has an indirect effect through its impact on EI. Previous studies in adolescents with obesity have demonstrated that exercise, re...