Taste and food reinforcement in non-overweight youth

A psychobioecological model to understand the income-food insecurity-obesity relationship

Food insecurity, defined by unpredictable access to food that may not meet a person's nutritional needs, is associated with higher BMI (kg/m2) and obesity. People with food insecurity often have less access to food, miss meals and go hungry, which can lead to psychological and metabolic changes that favor energy conservation and weight gain. We describe a conceptual model that includes psychological (food reinforcement and delay discounting) and physiological (thermic effect of food and substrate oxidation) factors to understand how resource scarcity associated with food insecurity evolves into the food insecurity-obesity paradox. We present both animal and human translational research to describe how behavioral and metabolic adaptations to resource scarcity based on behavioral ecology theory may occur for people with food insecurity. We conclude with ideas for interventions to prevent or modify the behaviors and underlying physiology that characterize the income-food insecurity-obesity relationship.

Child Weight Status: The Role of Feeding Styles and Highly Motivated Eating in Children

Although parental feeding plays an important role in child eating and weight status, high food motivation among children may also be a factor shaping how feeding impacts child weight. This study explored whether individual differences in preschool children’s food motivation interacted with mothers’ feeding styles in predicting subsequent child weight status. Participants included 129 Hispanic Head Start mother/child dyads. Data were collected at ages 4–5 years (Time 1) and 7–9 (Time 3). Staff measured heights/weights and observed children in an eating in the absence of hunger task. Mothers reported on feeding styles/practices and children’s eating behaviors. A principal components analysis derived a measure of highly motivated eating in children. Multiple regressions predicted Time 3 child BMI z-scores. Time 3 BMI z-scores were positively predicted by authoritative and indulgent feeding styles and negatively predicted by monitoring. Since feeding style interacted with highly motivated eating, separate regressions were run for high and low food motivation in children. Unexpectedly, results showed that authoritative feeding positively predicted Time 3 child BMI z-scores only for children showing low levels of food motivation. Characterizing differential parental feeding and child eating phenotypes may assist in tailoring childhood obesity prevention programs for the target populations.

Decision-Making Processes Related to Perseveration Are Indirectly Associated With Weight Status in Children Through Laboratory-Assessed Energy Intake

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 four-session, within-subjects laboratory study to investigate the relationships between decision-making processes, food intake, and weight status in 70 children 7-to-11-years-old. Decision-making was assessed with the Hungry Donkey Task (HDT), a child-friendly task where children make selections with unknown reward outcomes. Food intake was measured with three paradigms: (1) a standard ad libitum meal, (2) an eating in the absence of hunger (EAH) protocol, and (3) a palatable buffet meal. Individual differences related to decision-making processes during the HDT were quantified with a reinforcement learning model. Path analyses were used to test whether decision-making processes that contribute to children's (a) expected value of a choice and (b) tendency to perseverate (i.e., repeatedly make the same choice) were indirectly associated with weight status through their effects on intake (kcal). Results revealed that increases in the tendency to perseverate after a gain outcome were positively associated with intake at all three paradigms and indirectly associated with higher weight status through intake at both the standard and buffet meals. Increases in the tendency to perseverate after a loss outcome were positively associated with EAH, but only in children whose tendency to perseverate persistedacross trials. Results suggest that decision-making processes that shape children's tendencies to repeat a behavior (i.e., perseverate) are related to laboratory energy intake across multiple eating paradigms. Children who are more likely to repeat a choice after a positive outcome have a tendency to eat more at laboratory meals. If this generalizes to contexts outside the laboratory, these children may be susceptible to obesity. By using a reinforcement learning model not previously applied to the study of eating behaviors, this study elucidated potential determinants of excess energy intake in children, which may be useful for the development of childhood obesity interventions.

The influence of COVID-19-related stress on food motivation

The COVID-19 pandemic and public health measures to reduce its transmission have increased stress. Stress is associated with alterations in eating behavior which may be partly driven by effects on food-related motivation. To investigate effects of COVID-related stress on food motivation, we recruited adults (N = 429; 272 F, 157 M) to complete an online survey via Amazon MTurk in May 2020. Current COVID-related stress, retrospective pre-COVID stress, and motivation in relation to individualized preferred foods from five categories (sweet snacks, fruit, savory snacks, vegetables, and fast food) were assessed. Food motivation measures included willingness to wait, willingness to expend low effort [finger taps], willingness to expend high effort [jumping jacks], and willingness to pay for hypothetical delivery of the food item. Food motivation for each food type was assessed using a novel instrument designed for brief assessment of multiple aspects of food motivation across multiple food types. Participants were willing to pay the most for fast food followed by sweet snacks, and willing to wait longer for sweet snacks relative to other food types. While fast food and sweets also generated the most willingness to expend high and low effort, willingness to expend low effort for fruit was similar to that for fast food and sweets, and willingness to expend high effort for fruit was comparable to that for fast food. Participants were least willing to pay or expend low effort for vegetables. Higher COVID-related stress levels were associated with willingness to expend more effort and pay more for food items. These data collected during the pandemic demonstrate that highly processed and sweet foods have high motivating value across multiple measures of motivation, and COVID-related stress increases food motivation across food categories. Interventions to mitigate stress and target the link between stress and overeating may help to limit the effects of the COVID-19 pandemic on obesity.

Food reinforcement and habituation to food are processes related to initiation and cessation of eating

An individual bout of eating involves cues to start eating, as well as cues to terminate eating. One process that determines initiation of eating is food reinforcement. Foods with high reinforcing value are also likely to be consumed in greater quantities. Research suggests both cross-sectional and prospective relationships between food reinforcement and obesity, food reinforcement is positively related to energy intake, and energy intake mediates the relationship between food reinforcement and obesity. A process related to cessation of eating is habituation. Habituation is a general behavioral process that describes a reduction in physiological or affective response to a stimulus, or a reduction in the behavioral responding to obtain a stimulus. Repeated exposure to the same food during a meal can result in habituation to that food and a reduction in consumption. Habituation is also cross-sectionally and prospectively related to body weight, as people who habituate slower consume more in a meal and are more overweight. Research from our laboratory has shown that these two processes independently influence eating, as they can account for almost 60% of the variance in ad libitum intake. In addition, habituation phenotypes show reliable relationships with reinforcing value, such that people who habituate faster also find food less reinforcing. Developing a better understanding of cues to start and stop eating is fundamental to understanding how to modify eating behavior. An overview of research on food reinforcement, habituation and food intake for people with a range of weight status and without eating disorders is provided, and ideas about integrating these two processes that are related to initiation and termination of a bout of eating are discussed.

High reinforcing value of food is related to slow habituation to food

BACKGROUND

The rate of habituation to food and reinforcing value of food are processes that are related to food intake and body weight. Reinforcing value of food provides an index of the motivation to eat, while habituation provides an index on how repeated presentations of food relate to reduced behavioral and physiological responses to that food.

OBJECTIVE

To investigate the relationship between habituation phenotypes to salty, sweet and savory foods and reinforcing value of those foods.

DESIGN

A sample of 229 8-12-year-old children at risk for obesity completed reinforcing value and habituation tasks for foods that varied in savory, sweet or salty tastes. Multivariate Group Based Trajectory Modeling was used to create four unique patterns of habitation to foods based on detailed 10 s epochs of responding for food over a 24 min task. Differences in reinforcing value of food were assessed for these habituation phenotypes.

RESULTS

Results showed a graded relationship between the overall habituation phenotypes and reinforcing value of food, as those with the relatively flat habituation phenotype found food more reinforcing than those with phenotypes that showed rapidly decelerating responding across all taste categories.

CONCLUSIONS

Those who habituated slower found food more reinforcing than those with a rapid habituation phenotype. Implications of these phenotypes for understanding how habituation relates to food intake are discussed.

The consequences of exercise-induced weight loss on food reinforcement. A randomized controlled trial

BACKGROUND

Obesity remains a primary threat to the health of most Americans, with over 66% considered overweight or obese with a body mass index (BMI) of 25 kg/m2 or greater. A common treatment option many believe to be effective, and therefore turn to, is exercise. However, the amount of weight loss from exercise training is often disappointingly less than expected with greater amounts of exercise not always promoting greater weight loss. Increases in energy intake have been prescribed as the primary reason for this lack of weight loss success with exercise. Research has mostly focused on alterations in hormonal mediators of appetite (e.g.: ghrelin, peptide YY, GLP-1, pancreatic polypeptide, and leptin) that may increase hunger and/or reduce satiety to promote greater energy intake with exercise training. A less understood mechanism that may be working to increase energy intake with exercise is reward-driven feeding, a strong predictor of energy intake and weight status but rarely analyzed in the context of exercise.

DESIGN

Sedentary men and women (BMI: 25-35 kg/m2, N = 52) were randomized into parallel aerobic exercise training groups partaking in either two or six exercise sessions/week, or sedentary control for 12 weeks.

METHODS

The reinforcing value of food was measured by an operant responding progressive ratio schedule task (the behavioral choice task) to determine how much work participants were willing to perform for access to a healthy food option relative to a less healthy food option before and after the exercise intervention. Body composition and resting energy expenditure were assessed via DXA and indirect calorimetry, respectively, at baseline and post testing.

RESULTS

Changes in fat-free mass predicted the change in total amount of operant responding for food (healthy and unhealthy). There were no correlations between changes in the reinforcing value of one type of food (healthy vs unhealthy) to changes in body composition.

CONCLUSION

In support of previous work, reductions in fat-free mass resulting from an aerobic exercise intervention aimed at weight loss plays an important role in energy balance regulation by increasing operant responding for food.

Development of a measure of the relative reinforcing value of food versus parent-child interaction for young children

The relative reinforcing value (RRV) of food captures individual differences in the motivation to eat and is associated with weight status among infants, children, and adults. Currently, there is no concurrent measure of the RRV of food versus a non-food alternative for 4-to-5-year-old children. The present study aimed to develop and validate a measure of the RRV of food versus time spent interacting with a parent in the context of reading among 4-to-5-year-old children. The first phase of the study involved an online survey. Parents of 4-to-5 year olds (n = 102) reported their children's consumption frequency and liking for thirty-six snack foods. A priori criteria were used to identify snacks that were well-liked and served at least sometimes for use in the subsequent laboratory study. Then, a validation study was conducted in the laboratory to examine the construct validity of the finalized RRV task. Thirty-one parent-child dyads completed a laboratory visit, in which children's RRV of food versus time spent reading with a parent was measured concurrently on a progressive ratio reward schedule. Linear regression was used to assess validity of the task. Children's RRV of food positively and significantly predicted BMI z-scores among children with complete data (B = 0.41, p < 0.05, n = 28). Maximum schedules reached for food also positively and significantly predicted BMI z-scores (B = 0.30, p < 0.05). The relationship between maximum schedules reached for parent-child reading and BMI z-scores was in the expected direction, but this relationship was non-significant. Results support the validity and feasibility of the RRV paradigm used in the present study. Future research could continue to examine the measurement properties of this paradigm, as well as the potential for positive parent-child interactions to serve as a novel alternative to food.

The reinforcing value of food and non-food alternative: Associations with BMI z-score and percent fat mass

There is growing evidence of an association between the relative reinforcing value of food (RRVF; how hard a child is willing to work for a food versus a non-food reinforcer) and weight across many life stages, but few studies have examined this association among preschool age children. This study investigated the association between the RRVF (measured as the food reinforcing ratio (FRR)) and body mass index (BMI) z-score and percent fat mass (%FM), in 3 year-old children. The sample was comprised of 33 children who were 3 years of age (36-47 months). Children selected their favourite food reinforcer (cookie) and non-food (audiobook) reinforcer to be used in the FRR task, which was delivered using a sequential progressive fixed ratio reward schedule. Child height, weight and percent body fat using bioelectrical impedance analysis were assessed by trained research staff. Linear regression analyses showed that FRR was significantly and positively associated with BMI z-scores. FRR was not significantly associated with %FM. Findings from this study support the RRVF as a potential risk factor in the development of childhood obesity. Longitudinal research involving larger sample sizes would strengthen future research exploring associations between RRVF and body composition in preschool age children.

Percepción del gusto como factor de riesgo para obesidad infantil

Objetivo. Describir el papel de la percepción del gusto como factor de riesgo para el desarrollo de obesidad en niños. Material y métodos. Se realizó una búsqueda inicial de artículos científicos publicados en PubMed entre el 1 de enero de 2011 y el 20 de marzo de 2016 para el tema sobrepeso y obesidad en niños de entre 0 y 12 años. Los algoritmos utilizados fueron (Obesity OR Overweight) AND Taste perception, Satiation, Satiety response, Appetite, Appetite regulation, Habitua­tion, Taste receptors [MeSH] y PROP phenotype. En búsquedas subsecuentes se incluyeron artículos previos y posteriores a la fecha de la búsqueda general (hasta mayo 2018). Re­sultados. Las preferencias por los sabores inician desde la gestación, por lo que los niños que son expuestos a sabores dulces en etapas tempranas de la infancia aumentan su riesgo de habituación a éstos. Asimismo, las experiencias hedónicas dadas por la ingestión de alimentos y bebidas dulces refuerzan el consumo de estos alimentos, lo que propicia la selección de productos o bebidas de sabor dulce en etapas posteriores. Estas preferencias se han asociado con el desarrollo de obe­sidad en los niños. Las variantes genéticas relacionadas con la percepción del gusto también pueden contribuir a la selección de cierto tipo de alimentos. Sin embargo, su relación con una mayor ingestión de energía, así como con un mayor peso corporal, ha sido poco explorada y ha mostrado resultados inconsistentes. Conclusiones. Se requiere más evidencia para entender las interacciones ambientales y genéticas de la percepción del gusto, a fin de considerarlo un factor más en las intervenciones de política pública.

Influence of sedentary, social, and physical alternatives on food reinforcement

OBJECTIVE

This study examined the potential for nonfood alternative activities to compete with the reinforcing value of food. Participants rated the frequency and pleasantness of engaging in a variety of activities and made hypothetical choices between food and 4 types of alternatives; cognitive-enriching (reading, listening to music), social (attending a party or event), sedentary (watching TV), and physically active (running, biking).

METHOD

Two-hundred seventy-six adults completed an online survey using a crowdsourcing platform.

RESULTS

Adults with higher BMI reported engaging in fewer activities within the cognitive-enriching, social, and physically active categories. When examining how well each alternative activity type was able to compete with food, sedentary alternatives were associated with the highest food reinforcement, or were least able to compete with food reinforcers, as compared with cognitive-enriching, social, and physical. Social activities were associated with the lowest food reinforcement, or the best able to compete with food reinforcers.

CONCLUSION

These results suggest that increasing the frequency and range of nonfood alternative activities may be important to obesity. This study also suggests that the class of social activities may have the biggest impact on reducing food reinforcement, and the class of sedentary may have the smallest effect on food reinforcement. These tools have relevance to clinical interventions that capitalize on increasing access to behaviors that can reduce the motivation to eat in clinical interventions for obesity. (PsycINFO Database Record

Binary components of food reinforcement: Amplitude and persistence

BACKGROUND

Demand curves provide an index of how reinforcing a food is. Research examining the latent structure of alcohol and tobacco reinforcement identified two underlying components of reinforcement, amplitude and persistence. No research has assessed latent structure of food reinforcement and how these factors are related to BMI.

SUBJECTS AND METHODS

Participants were 297 adults from two studies that completed food purchasing tasks to assess the following measures of relative reinforcing efficacy (RRE) of food: intensity (Q₀): purchases made when the food was free or of very minimal price, O_max: maximum expenditure (purchases*price), P_max: price point where maximum expenditure was observed, breakpoint: first price where 0 purchases are made, and demand elasticity (α): quantitative non-linear relationship between purchasing and price. Principal components analysis was used to examine the factor structure of RRE for food across samples and types of food.

RESULTS

Both studies revealed two factor solutions, with P_max, O_max, breakpoint and α loading on factor 1 (persistence) and intensity (Q₀) loading on factor 2 (amplitude) across both high and low energy dense foods. Persistence reflects an aggregate measure of price sensitivity and amplitude reflects the preferred volume of consumption (how long vs. how much). The two factors accounted for between 91.7 and 95.4% of the variance in food reinforcement. Intensity for high energy dense foods predicted BMI for both studies (r = 0.18 and r = 0.22, p's < 0.05).

CONCLUSIONS

The latent factor structure was similar across two significantly different independent samples and across low and high energy dense snack foods. In addition, the amplitude of the demand curve, but not persistence, was related to BMI. These results suggest specific aspects of food reinforcement that can be targeted to alter food intake.

Behavioral Economic Factors Related to Pediatric Obesity

Behavioral economics (BE) suggests that food and activity choices are governed by costs, available alternatives, and reinforcement. This article reviews basic, translational, and intervention research using a BE framework with overweight or obese children up to age 18. We address BE concepts and methods, and discuss developmental issues, the continuum of BE intervention approaches, findings of studies focused on increasing the cost of unwanted behaviors (ie, energy-dense food intake and sedentary behavior) and decreasing the cost of desired behaviors (ie, healthy food intake and PA), and our team's recent basic behavioral studies using BE approaches with minority adolescents.

Genetic variations of the bitter taste receptor TAS2R38 are associated with obesity and impact on single immune traits

SCOPE

Changes in genetic variations affecting the taste receptor, type 2, member 38 (TAS2R38) may identify the interacting mechanism leading to obesity and potential associations with proteins partaking in innate immunity, such as surfactant protein D (SPD) and mannan-binding lectin (MBL).

METHODS AND RESULTS

We evaluated haplotypes of the bitter-taste receptor TAS2R38 in an identification sample of 210 women in different weight conditions, including anorexia nervosa and obesity. The association with SPD and MBL was tested in an independent sample picturing general population (n = 534). The relationship with obesity was validated in an extended final sample of 1319 participants. In the sample comprised of women in extreme weight conditions, increased obesity was identified in AVI/AVI subjects (OR = 2.5 [1.06-6.11], p = 0.035). In the sample picturing general population, increased SPD and MBL concentrations were found in nonsmoking AVI carriers. In this cohort, smoking and obesity blunted associations between TAS2R38 haplotypes and SPD and MBL. In the extended sample, the association of AVI/AVI haplotypes with increased obesity was also identified (OR = 1.4 [0.99/1.85], p = 0.049), being more robust in subjects aged <40 years (OR = 1.9 [1.06/3.42], p = 0.031).

CONCLUSION

Current data reinforce the impact of TAS2R38 gene on phenotypic and clinical outputs affecting obesity, showing significant associations with extreme weight conditions (i.e., obesity and anorexia nervosa), and changes in both olfactory capacity and immune traits.