Food reinforcement partially mediates the effect of socioeconomic status on body mass index

Translational science approaches for food insecurity research

Food insecurity is a pervasive problem that impacts health and well-being across the lifespan. The human research linking food insecurity to poor metabolic and behavioral health outcomes is inherently correlational and suffers from a high degree of variability both between households and even within the same household over time. Further, food insecurity is impacted by societal and political factors that are largely out of the control of individuals, which narrows the range of intervention strategies. Animal models of food insecurity are being developed to address some of the barriers to mechanistic research. However, animal models are limited in their ability to consider some of the more complex societal elements of the human condition. We believe that understanding the role that food insecurity plays in ingestive behavior and chronic disease requires a truly translational approach, and that understanding the health impacts of this complex social phenomenon requires understanding both its psychological and physiological dimensions. This brief review will outline some key features of food insecurity, highlighting those that are amenable to investigation with controlled animal models and identifying areas where integrating animal and human studies can improve our understanding of the psychological burden and health impacts of food insecurity. In the interest of brevity, this review will largely focus on food insecurity in the United States, as the factors that contribute to food insecurity vary considerably across the globe.

An acute social stressor decreases reinforcing value of both high and low energy-dense food in college students in a randomized controlled trial

It is well known that a large portion of the population elevates their intake of high energy-dense foods during times of stress; however, it is understudied whether stress affects the reinforcing value of a food reward. Further knowledge of this relationship may help us better understand the positive correlation between reinforcing value of food and obesity. Therefore, it was tested if an acute stressor would increase the reinforcing value of low or high energy-dense food. Participants (N = 70) were randomized to a stress or no-stress condition after which they were allowed to work to gain access to a food reward and reading time. To determine if high energy-dense food was specifically affected, half the participants from each stress manipulation were randomly assigned to work for either grapes or chocolate candies. Participants in the stress condition worked less for food access than those in the no-stress condition, for both low and high energy-dense foods, but stress did not affect the reinforcing value of reading time. These results indicate that, contrary to our hypothesis, in a sample of college students, an acute stressor decreased reinforcing value of food, with no difference between a low and high energy-dense food item.

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.

Glucose response to sugar challenge moderates the effect of insulin resistance on reinforcing value of sugar-sweetened yogurt

We have shown insulin resistance is associated with the choice of sugar-sweetened over monk fruit sweetened yogurt. This study extends this research by assessing the association between insulin resistance and reinforcing value for sugar versus monk fruit-sweetened yogurt, and testing the hypothesis that this effect is moderated by greater blood glucose response in people with insulin resistance. Eighteen people with overweight/obesity (BMI = 35.8 kg/m2, range 26.2-48.5) with varying degrees of insulin resistance (Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) = 2.6, range of 0.6-8.0) had blood glucose measured for 2 h after a sugar challenge. Over six days, they consumed, in a double-blind fashion, novel flavored-colored sugar or monk fruit-sweetened yogurts, and the reinforcing value of sugar or monk fruit-sweetened yogurts and delay discounting (DD) were measured. HOMA-IR (r = 0.62, p = .006) and insulin (r = 0.51, p = .03) were related to the reinforcing value of sugar-sweetened, but not monk fruit-sweetened yogurt (r = -0.07, -0.10, respectively). The blood glucose area under the curve moderated the relationship between HOMA-IR and the reinforcing value of sugar-sweetened yogurt (p = .02). People with greater HOMA-IR and greater blood glucose excursions responded the most for sugar-sweetened yogurt. These results extend previous research and confirm the hypothesis that individual differences in response to sugar may activate brain reward centers and condition people to prefer high-sugar foods. DD was related to sugar reinforcement (r = -0.46, p = .03), consistent with the idea that those with high sugar reinforcement desire immediate gratification, and DD moderated the relationship between HOMA-IR and the reinforcing value of sugar-sweetened yogurt (p < .001). Research should test whether reducing insulin resistance would permit people with insulin resistance to choose lower-sugar foods.

Parents, but not their children, demonstrate greater delay discounting with resource scarcity

BACKGROUND

Individuals with obesity tend to discount the future (delay discounting), focusing on immediate gratification. Delay discounting is reliably related to indicators of economic scarcity (i.e., insufficient resources), including lower income and decreased educational attainment in adults. It is unclear whether the impact of these factors experienced by parents also influence child delay discounting between the ages of 8 and 12-years in families with obesity.

METHODS

The relationship between indices of family income and delay discounting was studied in 452 families with parents and 6-12-year-old children with obesity. Differences in the relationships between parent economic, educational and Medicaid status, and parent and child delay discounting were tested.

RESULTS

Results showed lower parent income (p = 0.019) and Medicaid status (p = 0.021) were differentially related to greater parent but not child delay discounting among systematic responders.

CONCLUSIONS

These data suggest differences in how indicators of scarcity influence delay discounting for parents and children, indicating that adults with scarce resources may be shaped to focus on immediate needs instead of long-term goals. It is possible that parents can reduce the impact of economic scarcity on their children during preadolescent years. These findings suggest a need for policy change to alleviate the burden of scarce conditions and intervention to modify delay discounting rate and to improve health-related choices and to address weight disparities.

Delay Discounting and the Income-Food Insecurity-Obesity Paradox in Mothers

Food insecurity, defined as unpredictable access to food that may not meet a person's nutritional needs, is paradoxically associated with higher BMI (kg/m2) and obesity. Research has shown delay discounting, a behavioral economic measure of the preference for immediate rather than delayed rewards, is related to higher BMI, and moderates the relationship between income and food insecurity. Based on this research, we used regression models to test whether delay discounting, consideration of future consequences, and perceived stress were atemporal mediators of the food insecurity-BMI relation in 313 mothers, controlling for demographic variables. A secondary aim was to replicate the finding that delay discounting moderates the relationship between low income and high food insecurity. Results showed that low income was associated with higher food insecurity, and higher food insecurity was associated with higher BMI. Delay discounting was the only variable that was indirectly related to both paths of the food-insecurity-BMI relation. Delay discounting accounted for 22.2% of the variance in the low-income-food insecurity-obesity relation, and the total model accounted for 38.0% of the variance. The relation between low income and food insecurity was moderated by delay discounting. These data suggest that delay discounting is a potential mediator of the relationship between food insecurity and high BMI, which suggests reducing discounting in the future could be a novel target to reduce food insecurity and help people with food insecurity to reduce their excess body weight. Trial Registration. This trial is registered with NCT02873715.

Reinforcing value of food, enriched home environment, and changes in percent overweight in children

OBJECTIVE

The decision to eat is often a choice made in the context of food and non-food alternatives. However, no research, to the authors' knowledge, has assessed the combination of the motivation to eat, as indexed by the relative reinforcing value of food (RRVFOOD ), and the enriched home environment, i.e., access to activities that can serve as alternatives to eating on weight gain.

METHODS

This study used a cross-sectional design to study how RRVFOOD and the enriched home environment predict percent overweight change over 2 years in 291 children aged 6 to 9 years and of varying socioeconomic status.

RESULTS

Results showed that RRVFOOD and access to food were positively associated with baseline percent overweight, and an enriched home environment was negatively related to baseline percent overweight. RRVFOOD and an enriched home environment interacted to predict change in percent overweight. Children with a high relative RRVFOOD and a relatively non-enriched environment showed the greatest relative weight gain.

CONCLUSIONS

These results suggest that providing an enriched home environment may reduce the effects of food reinforcement and being motivated to eat on weight gain in childhood, and this represents a novel approach to intervention that can be used to strengthen current behavioral approaches to prevent obesity in children.

Insulin Resistance and Glycated Hemoglobin in Obesity Are Associated With Preference for Sugar-Sweetened Yogurt: A Pilot Study

OBJECTIVE

Insulin resistance is associated with elevated activation of food reward, which should be associated with an increased reinforcing value of food. Research has also shown that sugar is a macronutrient strongly associated with reward and reinforcing value of food. This research is designed to assess whether insulin resistance is associated with a stronger preference for sugar-sweetened, thus elevating blood glucose responses in obese people with varying degrees of insulin resistance.

METHODS

Thirteen people with obesity (body mass index, 39.1 kg/m 2 ; range, 30.0-45.1 kg/m 2 ) with varying degrees of insulin resistance (Homeostatic Model Assessment of Insulin Resistance, 5.2; range, 0.7-11.6) consumed novel flavored-colored yogurts that were sweetened with either sugar or monkfruit daily for 6 days to assess whether when given the choice of sugar-sweetened versus monkfruit-sweetened yogurts to consume, participants preferred sugar-sweetened yogurts.

RESULTS

Participants consumed a greater amount ( p = .009) and percentage ( p = .04) of sugar-sweetened yogurt earned than monkfruit-sweetened yogurt. The percent of sugar-sweetened versus monkfruit-sweetened yogurt consumed in relationship to amount earned was related to insulin resistance ( r = 0.64, p = .019), glycated hemoglobin ( r = 0.61, p = .027), insulin ( r = 0.58, p = .007), and glucose ( r = 0.56, p = .048).

CONCLUSIONS

Insulin resistance is associated with preference for sugar-sweetened foods in participants with obesity, which may make it hard to make dietary changes. Research is needed to assess whether treatments that improve insulin resistance also change the preference for sugar-sweetened or high-glycemic-index foods.

Reducing relative food reinforcement of infants using a music enrichment program: a randomized, controlled trial

BACKGROUND

Food reinforcement or one's motivation to eat may be established early in life; it might not be the food reinforcement per se that drives weight gain, but rather the imbalance between food and nonfood reinforcement.

OBJECTIVES

We implemented a 2-y randomized, controlled trial to assess the effects of a music enrichment program (music, n = 45) compared with an active play date control (control, n = 45) in 9- to 15-mo-old healthy infants who were strongly motivated to eat.

METHODS

The 12-mo intensive intervention phase included 4 semesters of Music Together® or a play date program (Winter, Spring, Summer, and Fall), comprised of once per week group meetings, followed by a 12-mo maintenance phase with monthly meetings. Parents were encouraged to listen to the Music Together® program CD or play with the play date group's toy with their infants at home, respectively. We performed a modified intention-to-treat analysis using all randomly assigned, non-excluded subjects for the outcome measures [relative reinforcing value of food (RRVfood), food reinforcement, music reinforcement, and weight-for-length z-score (WLZ)].

RESULTS

There were significant differential group changes across time for RRVfood (group × month; P = 0.016; Cohen's f2 = 0.034). The music group had significantly greater RRVfood decreases than the control group from baseline to the end of the intensive intervention phase (music change = -0.211; control change = -0.015; P = 0.002; Cohen's D = 0.379). However, these differences were not maintained during months 12-24 (music change = -0.187; control change = -0.143; P = 0.448; D = 0.087). We observed an overall moderation effect by sex for food reinforcement and WLZ. Boys in the music group had a significant attenuation in food reinforcement and WLZ compared with boys in the control group.

CONCLUSIONS

This study extends our knowledge in infant eating behavior by providing insight into the role of nonfood alternatives in altering one's motivation to eat. There may be sex differences in altering one's motivation to eat.This trial was registered at clinicaltrials.gov as NCT02936284.

The Effect of Financial Scarcity on Reinforcer Pathology: A Dyadic Developmental Examination

This study investigated the effects of experimentally manipulated scarcity on the reinforcing value of food (RRVfood) and delay discounting (DD), which, together, create reinforcer pathology (RP) among parents and offspring. A stratified sample of 106 families (53 parent/child aged 7−10 dyads & 53 parent/adolescent aged 15−17 dyads) from high- and low-income households visited our laboratory for three appointments. Each appointment included an experimental manipulation of financial gains and losses and DD and RRV tasks. The results showed that, regardless of food insecurity or condition, children had greater RP (β = 1.63, p < 0.001) than adolescents and parents. DD was largely unaffected by acute scarcity in any group, but families with food insecurity had greater DD (β = −0.09, p = 0.002) than food-secure families. Food-insecure parents with children responded to financial losses with an increase in their RRVfood (β = −0.03, p = 0.011), while food-secure parents and food-insecure parents of adolescents did not significantly change their responding based on conditions. This study replicates findings that financial losses increase the RRVfood among adults with food insecurity and extends this literature by suggesting that this is strongest for parents of children.

The effect of acute and chronic scarcity on acute stress: A dyadic developmental examination

BACKGROUND

Food insecurity, obesity, and psychological stress are interrelated constructs which are thought to be connected through increased energy intake, but the underlying mechanisms for these relationships remain unclear. The current study used experimental methods to investigate how financial losses may influence acute stress in the context of food insecurity for both parents and offspring. This study also sought to examine the effect of acute stress related to financial losses on the reinforcing value of food (RRV_food) and delay discounting (DD).

METHODS

One hundred and six families stratified by both offspring age (53 children aged 7-10, 53 adolescents aged 15-17) and household financial resources, visited our laboratory for three separate appointments. Each appointment included the experimental manipulation of financial gains and losses, saliva samples for cortisol assay, continuous heart rate monitoring, self-rated tension, and computer-based DD and RRV_food tasks. Participants also completed surveys to report perceived life stress level and food insecurity status.

RESULTS

Among all participants, financial losses were related to decreased heart rates and increased self-rated tension. Among parents reporting food insecurity, acute financial losses resulted in an increase in cortisol levels. Changes in cortisol, heart rate, and tension were not related to RRV_food or DD.

CONCLUSION

Food insecure parents are sensitive to financial losses and respond with an increase in cortisol. However, we found no evidence for a relationship between cortisol and RRV_food or DD. This sensitivity to financial losses did not extend to children or adolescents.

The Surgeon's Role in Addressing Racism and Achieving Health Equity

In the United States, the nation's health is not an organic outcome. It is not a coincidence that certain groups of people living in the United States experience higher premature death rates or poorer health outcomes than others. For centuries, racial and ethnic as well as geographic differences in health outcomes have been part of the American landscape, so entrenched in society that many people fail to recognize that health inequities were intentionally derived. A national crisis tends to magnify inequities in our society, but even more alarming is the fact that as the country becomes more racially and ethnically diverse in the coming years, the health inequities are projected to worsen if we do not proactively and immediately address them. As we continue to grapple with the lasting impact of the pandemic, it is of vital importance that we utilize this time to acknowledge, understand, and seriously address the health inequities that have historically plagued the country for over 400 years. As the United States works overtime to stem the tide of the COVID-19 pandemic, it must also work equally hard to move in a more equitable, inclusive, and healthier direction, not only because of the more than 83 000 Americans dying prematurely each year but also because of the economic and national security toll it will have if not effectively addressed.

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.

Delay discounting and obesity in food insecure and food secure women

OBJECTIVES

The relation between food insecurity (FI) and delay discounting (DD) and probability discounting (PD) for food and money was tested in women. In addition, discounting was tested as a variable that mediates the relation between obesity and FI.

METHOD

Women recruited from a community sample (N = 92) completed questionnaires. They completed the food choice questionnaire, the monetary choice questionnaire, measures for food and money probability discounting (which quantify sensitivity to risk aversion), and demographic measures.

RESULTS

Women with FI had higher rates of obesity and higher food DD compared to food-secure women. However, DD for money or probability discounting for food or money did not significantly differ between FI and food secure groups when controlling for significant covariates. Neither DD or PD significantly mediated the relation between FI and obesity.

CONCLUSIONS

These results suggest that FI is associated with greater impulsive food choice, but its association with other monetary discounting and probability discounting for food and money appears contingent upon other demographic factors. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Having less and wanting more: an investigation of socioeconomic status and reinforcement pathology

BACKGROUND

In the United states obesity and socioeconomic status (SES), or one's standing in society based on income, education, and/or occupation, are strongly associated. The mechanisms for this relationship may include having high levels of motivation to get food (reinforcing value of food; RRV) and low levels of inhibitory control (delay discounting; DD) which, when combined, is referred to as reinforcement pathology (RP). We sought to examine the relationships among multiple measures of household SES, RP, and age-adjusted body mass index (zBMI) among adolescents.

METHODS

These data were collected as part of ongoing longitudinal study of risk factors for obesity in 244 adolescents. The adolescents and one parent/guardian had height and weight measured and completed surveys. The adolescents completed an adjusting amount DD task and a computer-based RRV task. Analyses consisted of correlations among measures of SES and RRV, DD, and BMI z-scores. In the case of significant associations, multiple regression models were created with theoretically informed covariates.

RESULTS

Household income, parent/guardian education, parent/guardian occupation, and food insecurity status were all related to one another. Among the adolescents, a significant portion of the variance in RRV was accounted for by household income after controlling for covariates. For DD, it was parent/guardian education that was most associated after controlling for covariates.

CONCLUSION

When low income and low parent/guardian education occur together, there may be an increased risk of RP. Separately, food insecurity was predictive of higher parent/guardian BMI. Future research should continue to explore the effects of low income and parent/guardian education on RP among youth by examining them over time.

The association of food insecurity with the relative reinforcing value of food, BMI, and gestational weight gain among pregnant women

OBJECTIVE

Food insecurity is associated with obesity among adults. During pregnancy, food insecurity increases obesity risk among mothers and infants. This study investigated the association of food security with pre-pregnancy body mass index (BMI), gestational weight gain (GWG) adequacy to date, and the relative reinforcing value (RRV) of food during pregnancy.

METHODS

This secondary data analysis examined 258 pregnant women (mean gestational age = 21.21 ± 10.21 weeks) surveyed on pre-pregnancy weight, height, pregnancy due date and GWG to date, current diagnoses related to eating and pregnancy, and demographics. The survey also assessed current food security and RRV of meals, snacks, cognitive activities, and active activities. BMI was calculated from pre-pregnancy height and weight (kg/m²). Gestational weight gain adequacy to date was derived from the Institute of Medicine guidelines. Multivariable linear regression models were used to examine the relation of food security with pre-pregnancy BMI and RRVs of foods/activities. The relation between food security and GWG adequacy to date was examined using multinomial regression models.

RESULTS

Lower food security was related to both greater pre-pregnancy BMI (β = 0.60, p < .001) and greater RRV of snack foods (β = 3.46, p < .05), after controlling for covariates. Lower food security was also related to GWG to date below recommended levels (OR = 1.25, p < .05).

CONCLUSIONS

Food insecurity is related to higher relative food reinforcement during pregnancy, and greater pre-pregnancy weight status. Future research should replicate and extend these findings by assessing them longitudinally to better evaluate the directions of these relationships.

Sociodemographic factors influencing island foods consumption in the Pacific Islander Health Study

Objectives: Pacific Islander Americans are a small, but quickly growing population that experiences alarming disparities in obesity and obesity-related chronic illnesses influenced by dietary patterns. This population also has a unique culinary heritage including traditional foods and more contemporary imports such as tinned meats and refined carbohydrates. This analysis is a novel attempt to understand the sociodemographic factors influencing island foods consumption.Design: A sample of 240 Samoan and Tongan adults in California from the Pacific Islander Health Study was used. Following univariate and bivariate analyses, a series of four multivariable regression models were created to predict past week frequency of island foods consumption after sequential adjustment for demographic, socioeconomic, and cultural covariates.Results: Participants reported consuming island foods an average of 2.93 times in the previous week, with the largest proportion of participants (20.42%) reporting eating island foods 6 or more times. Age and Samoan ethnicity were initially significant, positive predictors of island foods consumption, but their effect was attenuated after addition of cultural covariates. With the third model that adjusted for birthplace, financial insecurity and Tongan birthplace were positive predictors. Both lost significance in the fourth and final model upon addition of cultural affinity, which was positively associated with island foods.Conclusion: Understanding how sociodemographic factors are associated with island foods consumption is a first step in understanding the broad way in which an ethnically specific dietary pattern may be associated with obesity-related chronic illness risk among Pacific Islander Americans.

Choice is relative: Reinforcing value of food and activity in obesity treatment

Persons with obesity find high-energy-dense food and sedentary behaviors highly reinforcing. Diets and exercise programs deprive individuals of many favorite foods and activities, which can counterproductively heighten their value and lead to relapse. Since the value of reinforcers depend on the alternatives available, one approach to reducing food and sedentary activity reinforcement is to build healthy alternative reinforcers. Current behavioral treatment programs for children and adults do not attempt to build alternative reinforcers as substitutes for unhealthy behaviors to reduce the impact of food or activity deprivation on the motivation to eat or be inactive. A goal of the next generation of obesity treatment programs should focus on development of healthy behaviors as reinforcers so that people will be motivated to engage in them. This article provides an overview of relationships among reinforcers, how understanding substitutes and complements can influence eating and activity, and how enriching a person's environment and providing choice architecture can enhance weight control. Ideas for translation of these basic behavioral economic principles to obesity treatment programs are discussed. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Food and non-food reinforcement among pregnant women

Excessive gestational weight gain (GWG) in pregnancy may be driven in part by greater motivation to eat, and studying the relative reinforcing value of food versus non-food commodities may provide insight into factors important for excessive GWG. This study was a cross-sectional examination of the relationship between women meeting the Institute of Medicine (IOM) guidelines for GWG and the relative reinforcing value of food vs. non-food commodities during pregnancy. Two-hundred and thirty-three pregnant women (1st trimester, n = 44; 2nd trimester, n = 105; 3rd trimester, n = 84), aged 18-40, were recruited via a crowdsourcing platform and completed an online survey. Relative food reinforcement (RRV_food), relative non-food activity reinforcement (RRV_active) and relative non-food cognitively enriching activity reinforcement (RRV_cognitive) were measured by a questionnaire at the point of contact. Self-reports of gestational age and weight gain during pregnancy were collected. The relationship between food and non-food reinforcement was assessed based on IOM classifications for weight gain during pregnancy. After adjustment for women's education level and parity, higher RRV_food (p = 0.036) and lower RRV_cognitive (p = 0.040) responses were associated with greater GWG. Food reinforcing ratio (FRR) analysis was then conducted to systematically examine the effect of non-food behaviors on GWG when food reinforcement was accounted for. Women who gained below the IOM weight gain guidelines had significantly higher FRR_cognitive than those gaining above (p = 0.013), indicating cognitively enriching activities may better compete with food among pregnant women. Interventions that help to increase the reinforcing value of cognitively enriching activities may be a new avenue to regulate eating to minimize GWG.

Reinforcing value and hypothetical behavioral economic demand for food and their relation to BMI

Food is a primary reinforcer, and food reinforcement is related to obesity. The reinforcing value of food can be measured by establishing how hard someone will work to get food on progressive-ratio schedules. An alternative way to measure food reinforcement is a hypothetical purchase task which creates behavioral economic demand curves. This paper studies whether reinforcing value and hypothetical behavioral demand approaches are assessing the same or unique aspects of food reinforcement for low (LED) and high (HED) energy density foods using a combination of analytic approaches in females of varying BMI. Results showed absolute reinforcing value for LED and HED foods and relative reinforcing value were related to demand intensity (r's = 0.20-0.30, p's < 0.01), and demand elasticity (r's = 0.17-0.22, p's < 0.05). Correlations between demographic, BMI and restraint, disinhibition and hunger variables with the two measures of food reinforcement were different. Finally, the two measures provided unique contributions to predicting BMI. Potential reasons for differences between the reinforcing value and hypothetical purchase tasks were actual responding versus hypothetical purchasing, choice of reinforcers versus purchasing of individual foods in the demand task, and the differential role of effort in the two tasks. Examples of how a better understanding of food reinforcement may be useful to prevent or treat obesity are discussed, including engaging in alternative non-food reinforcers as substitutes for food, such as crafts or socializing in a non-food environment, and reducing the value of immediate food reinforcers by episodic future thinking.

Bleak Present, Bright Future: Online Episodic Future Thinking, Scarcity, Delay Discounting, and Food Demand

Obesity is associated with steep discounting of the future and increased food reinforcement. Episodic future thinking (EFT), a type of prospective thinking, has been observed to reduce delay discounting (DD) and improve dietary decision making. In contrast, negative income shock (i.e., abrupt transitions to poverty) has been shown to increase discounting and may worsen dietary decision-making. Scalability of EFT training and protective effects of EFT against simulated negative income shock on DD and demand for food were assessed. In two experiments we showed online-administered EFT reliably reduced DD. Furthermore, EFT reduced DD and demand for fast foods even when challenged by negative income shock. Our findings suggest EFT is a scalable intervention that has implications for improving public health by reducing discounting of the future and demand for high energy dense food.

Gene and environment interaction: Is the differential susceptibility hypothesis relevant for obesity?

The differential susceptibility model states that a given genetic variant is associated with an increased risk of pathology in negative environments but greater than average resilience in enriched ones. While this theory was first implemented in psychiatric-genetic research, it may also help us to unravel the complex ways that genes and environments interact to influence feeding behavior and obesity. We reviewed evidence on gene vs. environment interactions that influence obesity development, aiming to support the applicability of the differential susceptibility model for this condition, and propose that various environmental "layers" relevant for human development should be considered when bearing the differential susceptibility model in mind. Mother-child relationship, socioeconomic status and individual's response are important modifiers of BMI and food intake when interacting with gene variants, "for better and for worse". While only a few studies to date have investigated obesity outcomes using this approach, we propose that the differential susceptibility hypothesis is in fact highly applicable to the study of genetic and environmental influences on feeding behavior and obesity risk.

Infant Temperament Is Associated with Relative Food Reinforcement

OBJECTIVE

Food reinforcement refers to how hard someone is motivated to work to gain access to food. Infant temperament is defined as behavioral styles, or constitutionally based individual differences in reactive and regulatory aspects of behavior. Identifying correlates of food reinforcement, such as infant temperament, may help identify infants at risk for future negative health consequences (e.g., overweight or obesity) of high food reinforcement.

METHODS

This study tested aspects of parent-reported negative reactivity and regulation and their associations with relative food reinforcement in a cross-sectional sample of 105 9- to 18-month-old infants. Hierarchical linear regression models were then used to predict infant food reinforcement for the temperament dimensions that were significantly related to it.

RESULTS

Two temperament dimensions, cuddliness (regulatory aspect) (B = -0.050, ΔR² = 0.074, p = 0.005) and rate of recovery from distress and arousal (reactive aspect) (B = -0.040, ΔR² = 0.045, p = 0.031), were inversely associated with relative food reinforcement.

CONCLUSION

Clarifying the nature of relationships between these two behavioral predictors, infant temperament and relative food reinforcement, and early obesity can elucidate the role of individual differences in early obesity risk and can further inform targets for early behavioral obesity preventive interventions.

Can Families Eat Better Without Spending More? Improving Diet Quality Does Not Increase Diet Cost in a Randomized Clinical Trial among Youth with Type 1 Diabetes and Their Parents

BACKGROUND

Although cost is a frequently cited barrier to healthful eating, limited prospective data exist.

OBJECTIVE

To examine the association of diet cost with diet quality change.

DESIGN

An 18-month randomized clinical trial evaluated a dietary intervention.

PARTICIPANTS AND SETTING

Youth with type 1 diabetes duration ≥1 year, age 8.0 to 16.9 years, receiving care at an outpatient tertiary diabetes center in Boston, MA, participated along with a parent from 2010 to 2013 (N=136). Eighty-two percent of participants were from middle- to upper-income households.

INTERVENTION

The family-based behavioral intervention targeted intake of whole plant foods.

MAIN OUTCOME MEASURES

Diet quality as indicated by the Healthy Eating Index 2005 (HEI-2005) (which measures conformance to the 2005 Dietary Guidelines for Americans) and whole plant food density (cup or ounce equivalents per 1,000 kcal target food groups) were calculated from 3-day food records of youth and parent dietary intake at six and four time points, respectively. Food prices were obtained from two online supermarkets common to the study location. Daily diet cost was calculated by summing prices of reported foods.

STATISTICAL ANALYSES PERFORMED

Random effects models estimated treatment group differences in time-varying diet cost. Separate models for youth and parent adjusted for covariates examined associations of time-varying change in diet quality with change in diet cost.

RESULTS

There was no treatment effect on time-varying diet cost for either youth (β -.49, 95% CI -1.07 to 0.08; P=0.10) or parents (β .24, 95% CI -1.61 to 2.08; P=0.80). In addition, time-varying change in diet quality indicators was not associated with time-varying change in diet cost for youth. Among parents, a 1-cup or 1-oz equivalent increase in whole plant food density was associated with a $0.63/day lower diet cost (β -.63, 95% CI -1.20 to -0.05; P=0.03).

CONCLUSIONS

Improved diet quality was not accompanied by greater cost for youth with type 1 diabetes and their parents participating in a randomized clinical trial. Findings challenge the prevailing assumption that improving diet quality necessitates greater cost.

Maternal diet quality and nutrient intake in the gestational period: results from the delta healthy sprouts comparative impact trial

BACKGROUND

A woman's diet while pregnant can play an important role in her reproductive health as well as the health of her unborn child. Diet quality and nutrient intake amongst pregnant women residing in the rural Lower Mississippi Delta (LMD) region of the United States is inadequate. The Delta Healthy Sprouts Project was designed to test the comparative impact of two home visiting programs on weight status, dietary intake, and health behaviors of women and their infants residing in the LMD region. This paper reports results pertaining to maternal diet quality and nutrient intake in the gestational period.

METHODS

The experimental arm (PATE) received monthly home visits beginning in the second trimester using the Parents as Teachers curriculum enhanced with a nutrition and lifestyle behavior curriculum. The control arm (PAT) received monthly home visits using the Parents as Teachers curriculum only. Maternal diet was assessed via 24-h dietary recall at gestational months (GM) 4 (baseline), 6, and 8. Diet quality was computed using the Healthy Eating Index-2010 (HEI-2010).

RESULTS

Gestational period retention rates for PAT and PATE arms were 77 % (33/43) and 67 % (26/39), respectively. Significant effects were not found for time, treatment, or time by treatment for the HEI-2010 total or component scores, macro- or micronutrient intake or percentage of women meeting recommended nutrient intakes.

CONCLUSIONS

Perhaps due to low participant enrollment and higher than expected rates of drop out and noncompliance, we were not able to demonstrate that the enhanced nutrition and lifestyle curriculum (PATE) intervention had a significant effect on diet quality or nutrient intake during pregnancy in this cohort of rural, Southern, primarily African American women.

TRIAL REGISTRATION

clinicaltrials.gov, NCT01746394. Registered 5 December 2012.

Understanding the double burden of malnutrition in food insecure households in Brazil

Household food insecurity (HFI) has been associated with both obesity among mothers and undernutrition among children. However, this association has not been well investigated in mother/child pairs living in the same household. The objective of this study was to examine the relationship of coexistence of maternal overweight and child stunting with HFI in Brazil. We conducted secondary data analyses of the 2006 Brazilian National Demographic and Health Survey. We analyzed the nutritional status of 4299 pairs of 15-49-year-olds mothers and their children under 5 years of age. The double burden of malnutrition (DBM) was defined as the presence of an overweight mother and a stunted child in the same household. HFI was measured with the Brazilian HFI Measurement Scale. The association between DBM and HFI was examined with hierarchical multivariable logistic regression analyses. Severe HFI was associated with DBM after adjusting for macroeconomic and household level socio-economic and demographic variables (Adjusted OR: 2.65 - CI: 1.17-8.53). Findings suggest that policies and programmes targeting HFI are needed to prevent the coexistence of child chronic undernutrition and maternal overweight/obesity in the same household. These investments are likely to be highly cost-effective as stunting has been identified as one of the major risk factors for poor child development and adult overweight/obesity and a strong risk factor for the development of costly chronic diseases including type 2 diabetes and cardiovascular disease.

Explaining educational disparities in adiposity: the role of neighborhood environments

OBJECTIVE

To examine the extent to which characteristics of the neighborhood built environment explain the association between adiposity and educational qualifications in Australian women.

METHODS

A community sample of 1,819 women (aged 18-66) from the Melbourne SESAW study provided information regarding their body mass index (BMI) and level of education. Objective measures of participants' residential neighborhood built environments were obtained using a Geographic Information System.

RESULTS

Compared with women with a high school degree or above, women who did not complete high school had higher average BMI, which was partially explained by lower density of sports facilities and living less proximally to the coastline and to supermarkets. In a multiple mediator model, which explained 16.6% of the educational disparity in BMI, the number of sports facilities and presence of the coastline within 2 km of participants' homes were significant mediators of the observed socioeconomic disparity in BMI.

CONCLUSIONS

The residential neighborhood environment may help to explain socioeconomic patterning of overweight and obesity in Australian women. These results provide further support for considering the built environment in obesity prevention initiatives, suggesting a potential role in decreasing social inequalities in obesity.

No food for thought: moderating effects of delay discounting and future time perspective on the relation between income and food insecurity

BACKGROUND

Low income is related to food insecurity, and research has suggested that a scarcity of resources associated with low income can shift attention to the present, thereby discounting the future.

OBJECTIVE

We tested whether attending to the present and discounting the future may moderate the influence of income on food insecurity.

DESIGN

Delay discounting and measures of future time perspective (Zimbardo Time Perspective Inventory, Consideration of Future Consequences Scale, time period of financial planning, and subjective probability of living to age 75 y) were studied as moderators of the relation between income and food insecurity in a diverse sample of 975 adults, 31.8% of whom experienced some degree of food insecurity.

RESULTS

Income, financial planning, subjective probability of living to age 75 y, and delay discounting predicted food insecurity as well as individuals who were high in food insecurity. Three-way interactions showed that delay discounting interacted with financial planning and income to predict food insecurity (P = 0.003). At lower levels of income, food insecurity was lowest for subjects who had good financial planning skills and did not discount the future, whereas having good financial skills and discounting the future had minimal influence on food insecurity. The same 3-way interaction was observed when high food insecurity was predicted (P = 0.008).

CONCLUSION

Because of the role of scarce resources on narrowing attention and reducing prospective thinking, research should address whether modifying future orientation may reduce food insecurity even in the face of diminishing financial resources.

Women who are motivated to eat and discount the future are more obese

OBJECTIVE

Food reinforcement and delay discounting (DD) independently predict body mass index (BMI), but there is no research studying whether these variables interact to improve prediction of BMI.

METHODS

BMI, the relative reinforcing value of high (PMAXHED ) and low (PMAXLED ) energy dense food, and DD for $10 and $100 future rewards (DD10 , DD100 ) were measured in 199 adult females.

RESULTS

PMAXHED (P = 0.017), DD10 (P = 0.003), and DD100 (P = 0.003) were independent predictors of BMI. The interaction of PMAXLED × DD10 (P = 0.033) and DD100 (P = 0.039), and PMAXHED × DD10 (P = 0.038) and DD100 (P = 0.045) increased the variance accounted for predicting BMI beyond the base model controlling for age, education, minority status, disinhibition, and dietary restraint. Based on the regression model, BMI differed by about 2 BMI units for low versus high food reinforcement, by about 3 BMI units for low versus high DD, and by about 4 BMI units for those high in PMAXHED , but low in DD versus high in PMAXHED and high in DD.

CONCLUSION

Reducing DD may help prevent obesity and improve treatment of obesity in those who are high in food reinforcement.

FTO polymorphisms moderate the association of food reinforcement with energy intake

Food reinforcement (RRVfood) is related to increased energy intake, cross-sectionally related to obesity, and prospectively related to weight gain. The fat mass and obesity-associated (FTO) gene is related to elevated body mass index and increased energy intake. The primary purpose of the current study was to determine whether any of 68 FTO single nucleotide polymorphisms (SNPs) or a FTO risk score moderate the association between food reinforcement and energy or macronutrient intake. Energy and macronutrient intake was measured using a laboratory ad libitum snack food consumption task in 237 adults of varying BMI. Controlling for BMI, the relative reinforcing value of reading (RRVreading) and proportion of African ancestry, RRVfood predicted 14.2% of the variance in energy intake, as well as predicted carbohydrate, fat, protein and sugar intake. In individual analyses, six FTO SNPs (rs12921970, rs9936768, rs12446047, rs7199716, rs8049933 and rs11076022, spanning approximately 251kbp) moderated the relationship between RRVfood and energy intake to predict an additional 4.9-7.4% of variance in energy intake. We created an FTO risk score based on 5 FTO SNPs (rs9939609, rs8050136, rs3751812, rs1421085, and rs1121980) that are related to BMI in multiple studies. The FTO risk score did not increase variance accounted for beyond individual FTO SNPs. rs12921970 and rs12446047 served as moderators of the relationship between RRVfood and carbohydrate, fat, protein, and sugar intake. This study shows for the first time that the relationship between RRVfood and energy intake is moderated by FTO SNPs. Research is needed to understand how these processes interact to predict energy and macronutrient intake.