Delay discounting and intake of ready-to-eat and away-from-home foods in overweight and obese women

The effectiveness of personalised food choice advice tailored to an individual's socio-demographic, cognitive characteristics, and sensory preferences

Personalised dietary advice has become increasingly popular, currently however most approaches are based on an individual's genetic and phenotypic profile whilst largely ignoring other determinants such as socio economic and cognitive variables. This paper provides novel insights by testing the effectiveness of personalised healthy eating advice concurrently tailored to an individual's socio-demographic group, cognitive characteristics, and sensory preferences. We first used existing data to build a synthetic dataset based on information from 3654 households (Study 1a), and then developed a cluster model to identify individuals characterised by similar socio-demographic, cognitive, and sensory aspects (Study 1b). Finally, in Study 2 we used the characteristics of 8 clusters to build 8 separate personalised food choice advice and assess their ability to motivate the increased consumption of fruit and vegetables and decreased intakes of saturated fat and sugar. We presented 218 participants with either generic UK Government "EatWell" advice, advice that was tailored to their allocated cluster (matched personalised), or advice tailored to a different cluster (unmatched personalised). Results showed that, when compared to generic advice, participants that received matched personalised advice were significantly more likely to indicate they would change their diet. Participants were similarly motivated to increase vegetable consumption and decrease saturated fat intake when they received unmatched personalised advice, potentially highlighting the power of providing alternative food choices. Overall, this study demonstrated that the power of personalizing food choice advice, based on a combination of individual characteristics, can be more effective than current approaches in motivating dietary change. Our study also emphasizes the viability of addressing population health through automatically delivered web-based personalised advice.

Exploring the impact of impulsivity and indulgent consumption on eating patterns of Chinese consumers

There is a growing concern about unhealthy eating habits and their impact on public health, underscoring the importance of research to understand its determinants and encourage healthy food habits. Using behavioural economic insights in researching dietary habit offer advantages beyond the scope of observational studies. Therefore, this paper examines impulsivity, self-indulgence, prudence and their associations with an individual's eating habits and body mass index (BMI). Data were collected from a sample of 487 Chinese participants. Most participants (88%) had good eating habits based on the Healthy Eating Assessment score. The findings of a logistic regression analysis investigating the determinants of individual dietary behaviour based on participants' self-rating of their overall dietary habits indicate that consumers who showed temporal impulsivity for favourite food tend to have poorer habits of eating healthy foods. The results of a multiple linear regression examining the factors that influence eating habits from a composite score of the Healthy Eating Assessment indicate that the score is better with temporal impulsivity for healthy food and poor with temporal impulsivity for unhealthy food. Further, the score decreases with impulsivity measured as low self-control. The control variables, age and gender, are also significant. The findings of a linear regression analysis exploring the determinants of BMI and their association with impulsivity, self-indulgence and prudence indicate that individuals with higher impulsivity measured as low self-control are mostly in the higher BMI category. These findings are important for designing and implementing public health initiatives to promote healthier dietary habits.

Recent Experience Affects Delay Discounting: Evidence across Temporal Framing, Signs, and Magnitudes

Delay discounting, the decrease in outcome value as a function of delay to receipt, is an extensive area of research. How delays are framed (i.e., temporal framing), as well as the sign and magnitude of an outcome, produce important effects on the degree to which outcomes are discounted. Here, we examined how recent experience (i.e., order of presentation) modifies these well-known findings. Experiment 1 examined the effects of temporal framing across gains and losses. Regardless of outcome sign, the order of task presentation affected the effect of temporal framing. In particular, when typical delay frames (e.g., 1 week) preceded delays framed as actual dates (e.g., February 15), discounting was less in the date-framed task. However, when dates were followed by the delay frame, there was no difference in the degree of discounting. The experience of date-framed delays persisted or carried over to the delay-framed task. Experiment 2 examined recent experience and the magnitude effect. In particular, $10 and $100 were discounted similarly between-subjects when it was the first task completed. However, once participants completed the second magnitude task, the magnitude effect was present both within-subjects and across subjects. Furthermore, $10 was discounted more steeply when it followed $100, and $100 was discounted less steeply when it followed $10. The impact of recent experience on delay discounting has important implications for understanding mechanisms that may contribute to delay discounting. Recent experience should be considered when designing delay discounting experiments as well as when implementing interventions to reduce steep delay discounting.

How Do Anger and Impulsivity Impact Fast-Food Consumption in Transitional Age Youth?

Introduction

Consumption of fast food has been linked to psychiatric distress, violent behaviors, and impulsivity in adolescents. The relationship between eating fast food, anger, and impulsivity has not been widely investigated. The National Consortium on Alcohol and Neurodevelopment in Adolescence community-based cohort consists of 831 youth, half at elevated risk factors for substance use disorders during adolescence, followed annually.

Methods

Impulsivity using Urgency, Premeditation, Perseverance, and Sensation Seeking Impulsive Behavior scale from annual assessments was examined in relation to self-reported fast-food consumption frequency and mobile application questions of anger. This study tested the hypotheses that youth anger may be predicted by fast-food consumption frequency and impulsivity using multiple regression, in addition to whether adolescent fast-food consumption frequency may be predicted by anger and impulsivity.

Results

Among youth, higher anger levels and impulsivity predicted greater frequency of fast-food consumption, and greater fast-food consumption frequency and impulsivity predicted higher anger levels.

Conclusions

This study's longitudinal findings are consistent with those of other studies that have found fast-food consumption and anger associated with impulsivity and also reveal a bidirectional link between anger and fast-food consumption. These results may point attention to food selection considerations for those at risk of anger and poorer psychiatric outcomes.

The Use of Nonmonetary Outcomes in Health-Related Delay Discounting Research: Review and Recommendations

Delay discounting (DD) refers to the tendency to devalue an outcome as a function of its delay. Most contemporary human DD research uses hypothetical money to assess individual rates of DD. However, nonmonetary outcomes such as food, substances of misuse, and sexual outcomes have been used as well, and have advantages because of their connections to health. This article reviews the literature on the use of nonmonetary outcomes of food, drugs, and sexual outcomes in relation to health and reinforcer pathologies such as substance use disorders, obesity, and sexual risk behaviors, respectively, and makes a case for their use in discounting research. First, food, substances, and sex may be more ecologically valid outcomes than money in terms of their connections to health problems and reinforcer pathologies. Second, consistent trends in commodity-specific (i.e., domain) effects, in which nonmonetary outcomes are discounted more steeply than money, enhance variation in discounting values. Third, commodity-specific changes in discounting with treatments designed to change health choices are described. Finally, methodological trends such as test-retest reliability, magnitude effects, the use of hypothetical versus real outcomes, and age-related effects are discussed in relation to the three outcome types and compared to trends with monetary discounting. Limitations that center around individual preferences, nonsystematic data, and deprivation are discussed. We argue that researchers can enhance their DD research, especially those related to health problems and reinforcer pathologies, with the use of nonmonetary outcomes. Recommendations for future directions of research are delineated.

Aging and Neural Vulnerabilities in Overeating: A Conceptual Overview and Model to Guide Treatment

Given the vulnerability of older adults to chronic disease and physical disability, coupled with the threat that obesity poses to healthy aging, there is an urgent need to understand the causes of positive energy balance and the struggle that many older adults face with intentional weight loss. This paper focuses on neural vulnerabilities related to overeating in older adults, and moderating variables that can have either favorable or unfavorable effect these vulnerabilities. Research from our laboratory on older adults with obesity suggests that they are prone to similar neural vulnerabilities for overeating that have been observed in younger and middle-aged populations. In addition, following brief postabsorptive states, functional brain networks both in the resting state and in response to active imagery of desired food are associated with 6-month weight loss. Data reviewed suggest that the sensorimotor network is a central hub in the process of valuation and underscores the central role played by habits in overeating. Finally, we demonstrate how research on the neural vulnerabilities for overeating offers a useful framework for guiding clinical decision-making in weight management.

Definitions and Assessment Methods of ‘Home Cooking’ in Studies with Dietary Variables: A Scoping Review

Home cooking is a complex idea that involves multiple skills and behaviors and can be interpreted differently. Using six databases (two of which were Japanese), this scoping review examined the definitions and methods used in studies investigating the relationship between home cooking and dietary variables. Of the 40 studies (2 in Japanese) included in this review, 8 provided definitions but did not specify the extent or level that convenience foods can be allowed in food preparation. The methods were classified into two categories, namely, perception-dependent (n = 29) if using a self-reported instrument, or perception-independent (n = 11) if based on investigators’ classification. Subsequently, indicators of home cooking were classified based on survey attributes (e.g., frequency, location). All but five studies used single indicators, primarily the preparation frequency (n = 18). Quality of analysis was also evaluated. Studies that used multiple indicators or perception-independent methods showed high or moderate overall quality. In contrast, studies that used single indicators based on perception-dependent methods tended to have a low overall quality. The consistency of the relationship between home cooking and dietary variables depended on study quality. In conclusion, the definitions of home cooking were inconsistent across studies, and lacked consensus for examining the association between dietary outcomes.

Implementing family-based behavioral treatment in the pediatric primary care setting: Design of the PLAN study

Family-based behavioral treatment (FBT) is an evidence-based treatment for pediatric obesity. FBT has primarily been implemented in specialty clinics, with highly trained interventionists. The goal of this study is to assess effectiveness of FBT implemented in pediatric primary care settings using newly trained interventionists who might implement FBT in pediatric practices. The goal is to randomize 528 families with a child with overweight/obesity (≥85th BMI percentile) and parent with overweight/obesity (BMI ≥ 25) across four sites (Buffalo and Rochester, New York; Columbus, Ohio; St. Louis, Missouri) to FBT or usual care and obtain assessments at 6-month intervals over 24 months of treatment. FBT is implemented using a mastery model, which provides quantity of treatment tailored to family progress and following the United States Preventive Services Task Force recommendations for effective dose and duration of treatment. The primary outcome of the trial is change in relative weight for children, and secondarily, for parents and siblings who are overweight/obese. Between group differences in the tendency to prefer small immediate rewards over larger, delayed rewards (delay discounting) and how this is related to treatment outcome is also evaluated. Challenges in translation of group-based interventions to individualized treatments in primary care settings, and in study implementation that arose due to the COVID-19 pandemic are discussed. It is hypothesized that the FBT intervention will be associated with better changes in relative weight for children, parents, and siblings than usual care. The results of this study can inform future dissemination and implementation of FBT into primary care settings.

THE RELATIVE REINFORCING VALUE OF SNACK FOOD IS A SIGNIFICANT PREDICTOR OF FAT LOSS IN WOMEN WITH OVERWEIGHT OR OBESITY

Reinforcing Relative Value (RRV) of food and impulsivity are associated with energy intake and obesity. The study investigated the degree to which changes in RRV and impulsivity independently or interactively predict change in body weight and composition in women with overweight or obesity engaged in either a fast or in a slow weight loss programs. Body weight, body composition, Impulsivity (Barratt Impulsiveness Scale), RRV snack (computerized Behavioural Choice Task) were measured at baseline and post-intervention in 30 women with obesity undergoing either slow (n= 14 -500 kcal/day, 20 weeks) or fast n=16 (-1000kcal/day, 10 weeks) weight reduction. No group*time effects were noted on body composition, impulsivity or RRV, so participants from both groups were pooled for analysis. Multiple regression analyses indicated that none of the impulsivity variables predicted weight- or fat mass (FM) loss. However, Δ RRV snack predicted ΔFM (r=0.40, P=0.046), whereby greater increases in RRV snack were associated with less FM loss. Results indicate that different rates of weight loss do not differentially affect RRV snack or impulsivity traits. However, changes in RRV snack predicted FM loss, suggesting that dietary interventions that either mitigate increases or foster reductions in the RRV snack may yield greater reductions in adiposity. Trial Registration clinicaltrials.gov identifier: NCT04866875 NOVELTY POINTS • No differences in RRV of food were noted between fast and slow weight loss • Weight loss from combined fast and slow groups led to a moderate-sized reduction in the total impulsivity • Greater diet-induced increases in RRV snack was associated with less body fat-loss.

Temporal discounting as a candidate behavioral marker of obesity

Although obesity is a result of processes operating at multiple levels, most forms result from decision-making behavior. The aim of this review was to examine the candidacy of temporal discounting (TD) (i.e. the reduction in the value of a reinforcer as a function of the delay to its receipt) as a behavioral marker of obesity. For this purpose, we assessed whether TD has the ability to: identify risk for obesity development, diagnose obesity, track obesity progression, predict treatment prognosis/outcomes, and measure treatment effectiveness. Three databases (Pubmed, PsycINFO, and Web of Science) were searched using a combination of terms related to TD and obesity. A total of 153 papers were reviewed. Several areas show strong evidence of TD's predictive utility as a behavioral marker of obesity (e.g., distinguishing obese from non obese). However, other areas have limited and/or mixed evidence (e.g., predicting weight change). Given the positive relationship for TD in the majority of domains examined, further consideration for TD as a behavioral marker of obesity is warranted.

Healthful choices depend on the latency and rate of information accumulation

The drift diffusion model provides a parsimonious explanation of decisions across neurobiological, psychological and behavioural levels of analysis. Although most drift diffusion model implementations assume that only a single value guides decisions, choices often involve multiple attributes that could make separable contributions to choice. Here we fit incentive-compatible dietary choices to a multi-attribute, time-dependent drift diffusion model, in which taste and health could differentially influence the evidence accumulation process. We find that these attributes shaped both the relative value signal and the latency of evidence accumulation in a manner consistent with participants' idiosyncratic preferences. Moreover, by using a dietary prime, we showed how a healthy choice intervention alters multi-attribute, time-dependent drift diffusion model parameters that in turn predict prime-dependent choices. Our results reveal that different decision attributes make separable contributions to the strength and timing of evidence accumulation, providing new insights into the construction of interventions to alter the processes of choice.

Hedonic Hunger Is Associated with Intake of Certain High-Fat Food Types and BMI in 20- to 40-Year-Old Adults

BACKGROUND

Hedonic hunger occurs in response to a desire to consume food for pleasure. The μ-opioid system regulates the hedonic impact of food and the opioid receptor mu 1 gene (OPRM1) polymorphism has been associated with fat intake.

OBJECTIVES

The aim of this study was to determine whether the intake of high-fat food is associated with hedonic hunger and the OPRM1 polymorphism and whether these variables are related to BMI.

METHODS

Participants were 20- to 40-y-old women and men enrolled in Poznań, Poland in 2016-2018. The frequency of consumption of high-fat food was measured using a validated application for mobile devices. Hedonic hunger was assessed with the use of the Power of Food Scale (PFS). PFS1, PFS2, and PFS3 scores were generated for food available, food present, and food tasted, respectively. Genotyping of rs1799971 in the OPRM1 gene was performed using TaqMan probes. The associations were analyzed using linear regression or logistic regression, as appropriate.

RESULTS

Hedonic hunger scores were not associated with total high-fat food intake. Total PFS was associated with snack intake (β: 0.16, P = 0.0066). PFS1 was positively associated with healthy high-fat food intake (β: 0.27, P = 0.0001) and PFS2 with sweet high-fat food and fast-food intake (β: 0.27, P = 0.0030). OPRM1 genotype and hedonic hunger interacted on fast-food intake (β: -0.17; P < 0.0154). Total PFS and PFS2 increased the chance of having a BMI ≥ 25 kg/m2 (OR: 1.43; 95% CI: 1.03, 2.01; P = 0.0335 and OR: 1.89; 95% CI: 1.37, 2.61; P = 0.0001, respectively), whereas PFS3 decreased it (OR: 0.61; 95% CI: 0.41, 0.87; P = 0.0082).

CONCLUSIONS

Hedonic hunger is associated with the intake of selected types of high-fat food, but not with its total intake, in people aged 20-40 y. Associations between hedonic hunger and fast-food intake can be modified by OPRM1 genotype. Hedonic hunger is associated with BMI.

Sensitization of the reinforcing value of food: a novel risk factor for overweight in adolescents

Background and Objectives

The relative reinforcing value (RRV) of food is associated with increased energy intake and obesity and increases in RRV of food after repeated intake (sensitization) are related cross-sectionally and prospectively to higher BMI in adults. We examined the factors, such as delay discounting (DD), associated with sensitization of RRV of high energy density (HED) and low energy density (LED) food and how sensitization relates to zBMI in adolescents. We hypothesized that sensitization to HED food would be positively associated with zBMI, that sensitization to LED food would be negatively associated with zBMI, that DD would be associated with HED sensitization, and that LED sensitization and DD would moderate the relationships between HED sensitization and zBMI.

Subjects and Methods

A population-based sample of 207 adolescents without obesity, aged 12 – 14 years was studied from June 2016 – March 2019. The RRV of LED and HED foods were measured before and after two weeks of daily consumption along with zBMI and other potential factors related to eating and weight, including dietary restraint, hunger, food liking, and delay discounting (DD). Hierarchical regression models were used to determine the associations between these factors and sensitization and zBMI. We also examined LED sensitization and DD as potential moderators of the relationship between sensitization and zBMI.

Results

As hypothesized, dietary restraint and sensitization to HED food were associated with greater zBMI. Contrary to our original hypotheses, DD was not associated with sensitization, there was no relationship between sensitization to LED food and zBMI and neither LED sensitization or DD moderated the relationship between HED sensitization and zBMI.

Conclusions

Sensitization to repeated intake of HED food was associated with higher zBMI in adolescents without obesity. Sensitization may be a novel behavioral phenotype that may relate to overweight in youth.

Low subjective socioeconomic status alters taste-based perceptual sensitivity to the energy density of beverages

Lower socioeconomic status (SES) is associated with increased consumption of energy-dense foods and sugar-sweetened beverages. Recent findings suggest that the mere perception of having lower subjective SES (SSES) compared to others was sufficient to elicit heightened preferences and consumption of higher energy foods and meals. This increased drive for energy intake associated with low SSES may be accompanied by heightened perceptual sensitivity to the presence of energy in foods, which may aid discrimination and selection of energy-dense foods. The present study tested this prediction by investigating whether acute experiences of low SSES may produce subsequent shifts in perceptual sensitivity to the energy density of beverages. Participants performed two taste tests on 6 iced tea beverages that varied in energy density prior to (at baseline) and after an experimental SSES manipulation. There were no differences in general frequency of ice tea consumption across the SSES conditions. Results revealed that participants were better at perceiving beverages that were higher in energy to be more energy dense following the low SSES manipulation (compared to baseline evaluations). By contrast, participants in the high SSES and neutral control conditions exhibited no overall consistent change in sensitivity to perceived energy density across the beverages following the manipulation. Additionally, no effects of SSES manipulation were observed for rated palatability of the beverages. These findings demonstrate that subjective experiences of having inadequate socioeconomic resources may produce taste-based perceptual shifts that increase sensitivity to the presence of energy in foods, potentially through heightened attentiveness to or expectations of sensory characteristics that signal energy (i.e., sweetness, texture). Such perceptual shifts may have been adaptive for facilitating the discrimination and selection of energy-dense foods in the face of resource insecurity. Importantly, this study suggests that merely perceiving a socioeconomic disadvantage may enhance identification and consumption of energy-dense foods and beverages, which may represent a psychosocial process that contributes to socioeconomic disparities in consumption of energy dense foods, and may be operational via heightened perceptual sensitivity to sensory cues associated with the presence of energy in the consumed food.

The effect of repeated episodic future thinking on the relative reinforcing value of snack food

Obesity is related to delay discounting and relative reinforcing value of food. Episodic future thinking reduces delay discounting after one engagement. The effects of repeated engagement in episodic future thinking are unknown. We explored the effects of daily episodic future thinking on delay discounting, energy intake, and relative reinforcing value of food. Participants completed a delay discounting task, ad libitum buffet, and relative reinforcing value task following one engagement in episodic future thinking/episodic recent thinking and again after 1 week. One week of daily episodic future thinking did not reduce delay discounting compared to one engagement or episodic recent thinking. Engaging in episodic future thinking daily does not impact delay discounting, relative reinforcing value of snack food, or ad lib energy intake compared to one engagement in episodic future thinking.

Temporal discounting does not influence body mass index

The prevalence of obesity has driven searches for cognitive or behavioural economic factors related to Body Mass Index (BMI). One candidate is delay discounting: those who prefer smaller sooner rewards over larger but later rewards are hypothesised to have higher BMI. The findings in the literature are mixed however, with meta analyses suggesting only a very small correlation between discounting and BMI. Here we present novel empirical data (N=381) and Bayesian analyses which suggest no such relationship between discounting of either monetary or weight loss rewards and BMI. We also find evidence against our novel proposal that discounting moderates the rate of BMI gain over time. We also present our data in the context of a random effects Bayesian meta-analytical result which does suggest the presence of a small correlation overall. The strength of the correlation is so weak (2.25% shared variance) that its practical significance may be minor to non existent. However because we found decisive evidence for unaccounted for study-level variance, due to study heterogeneity, we argue that we should treat such meta-analytic correlations with extreme caution. While the relationship between discounting and health outcomes such as BMI remain theoretically appealing, our empirical and meta-analytic results suggest we should be cautious in inferring a correlational, let alone a causal, role for discounting processes in driving BMI or moderating BMI gain with age.

Linking risk attitudes, time preferences, and body mass index in Catalonia

Obesity is projected to increase in the coming years, despite the various socioeconomic policies implemented by governments and policy makers. As a result, some studies have suggested that obesity should be looked at from a psychological point of view, that is, individuals' propensity to become addicted to the consumption of fat-rich foods. Although previous studies have supported this, the results have been inconclusive: methodologically and geographically. This study uses a robust approach to elicit the risk and time preferences of food consumers. It goes further to ascertain the correlations between these parameters and obesity. Despite the methodological and geographical differences, our results support a strong relationship between body mass Index and risk aversion, but not for loss aversion. In addition, time discounting significantly influences individuals' propensity to increase body mass Index.

An ecological momentary episodic future thinking intervention on mother's weekly food purchases

BACKGROUND

Imagining one's own future (episodic future thinking, EFT) has helped mothers with overweight purchase healthier groceries during an online shopping task in the laboratory. The present study explored whether delivering an EFT intervention to participants' devices via an ecological momentary intervention (EMI) tool would help mothers purchase healthier food at brick-and-mortar stores.

METHOD

Participants (N = 43, mothers 31-52 years of age, BMI ≥ 24.9 kg/m2) were randomized to EFT or standardized episodic thinking (SET). EFT cues include a positive and vivid description of future events while SET cues focus on the recent experience of playing games in the laboratory. Cues were uploaded to participant profiles on an EMI site. Participants were trained on how to read and listen to cues as well as how to detail purchases. Participants received text reminders to listen to cues before shopping and returned with receipts the following day. Receipt data was analyzed to derive dependent variables, calories, and nutrients purchased per person. Correlations were used to analyze associations between study variables of interest, and ANOVAs were conducted to compare dietary variables by group.

RESULTS

Participants in the EFT group purchased fewer calories, fewer grams of fat, fewer grams of saturated fat, and fewer miligrams of sodium than participants in the SET control group.

CONCLUSION

Delivering EFT cues to participant devices may be a promising way to improve the calorie and nutrient content of food purchases. Future research should include a longer follow-up and analyze calorie changes over time. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Reinforcer pathology: Narrative of hurricane-associated loss increases delay discounting, demand, and consumption of highly palatable snacks in the obese

Reinforcer pathology is derived from the integration of two measures: (a) self-control (i.e., delay discounting), and (b) reward valuation (i.e., behavioral economic demand). Narrative theory asserts that vividly imagining oneself in a hypothetical, yet realistic, scenario can acutely alter decision making, valuation of reinforcers such as food, and how much food is consumed. The present study measured changes in reinforcer pathology for highly palatable snacks following either a negative or neutral scenario in obese individuals. Participants (N = 48), with a body mass index of 30 or greater, rated their liking of 7 calorie-dense snack items and completed discounting and purchase demand tasks for their top-rated snack. Participants then read a randomly assigned hypothetical scenario (i.e., a devastating hurricane [negative] or minor storm [neutral]), completed the tasks again, and were given ad libitum access to their top 3 ranked snack foods. Results indicated that delay discounting, demand for participants' top-rated snack food, and negative affect all increased in the hurricane group compared with the minor storm group. The hurricane group also consumed more calories, even when hunger was standardized with a preload meal bar. Consistent with reinforcer pathology, these results suggest that vivid consideration of a devastating scenario constricts the temporal window and increases demand for hedonic snack foods among obese individuals. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Delay discounting and household food purchasing decisions: The SHoPPER study

OBJECTIVE

Delay discounting is a neurocognitive trait that has been linked to poor nutritional health and obesity, but its role in specific dietary choices is unclear. This study tested whether individual differences in delay discounting are related to the healthfulness of household food purchases and reliance on nonstore food sources such as restaurants.

METHOD

The food purchases of 202 primary household food shoppers were objectively documented for 14 days through a food receipt collection and analysis protocol. The nutrient content of household food purchases was derived for each participant, and the overall diet quality (Healthy Eating Index-2015) and energy density (kcal/g) of foods and beverages were calculated. The proportion of energy from nonstore food sources was also derived. Delay discounting was assessed with a choice task featuring hypothetical monetary rewards.

RESULTS

Data were available for 12,624 foods and beverages purchased across 2,340 shopping episodes. Approximately 13% of energy was purchased from restaurants and other nonstore food sources. Steeper discounting rates were associated with lower overall Healthy Eating Index-2015 scores and a higher energy density (kcal/g) of purchased foods. Associations were attenuated but remained statistically significant when accounting for body mass index and sociodemographic variables. Discounting rates were unrelated to reliance on nonstore food sources or the energy density of purchased beverages.

CONCLUSIONS

Delay discounting is related to the healthfulness of food purchases among primary household shoppers. As food purchasing is a key antecedent of dietary intake, delay discounting may be a viable target in dietary and weight management interventions. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Exploring preferences for variable delays over fixed delays to high-value food rewards as a model of food-seeking behaviours in humans

Foraging and operant models suggest that animals will tolerate uncertainty or risk to obtain food quickly. In modern food environments, sustained access to quick energy-dense foods can promote weight gain. Here, we used a discrete-choice procedure to examine peoples' decisions about when next to eat high-value, palatable food rewards, probabilistically delivered immediately or following longer delays. In Experiment 1, moderately hungry young females showed consistent preferences for a variable delay option that delivered food rewards immediately or following long delays over a fixed delay option that delivered the same rewards following intermediate delays. These preferences were stronger in females with higher BMIs compared with lower BMIs, suggesting that quick food can enhance the value of uncertain or 'risky' food-seeking strategies in individuals vulnerable to future weight gain. In Experiment 2, prior exposure to a subtle and not easily identifiable food aroma increased selections of the variable delay option following delayed food rewards in a mixed sample of male and female adults, providing preliminary evidence that food cues can sustain uncertain food-seeking strategies. These data highlight a working hypothesis that the rapid delivery and consumption of food rewards, and food cues, can increase risk-tolerance in the food-seeking behaviours of individuals who are vulnerable to weight gain. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

Climatic burden of eating at home against away-from-home: A novel Bayesian Belief Network model for the mechanism of eating-out in urban China

Dietary patterns of eating away-from-home (AFH) considerably differ from those of eating at home in urban China, thus generating varied carbon footprints. However, few studies have investigated the effect of eating places on diet-related climatic burden, and few have modelled the mechanism under the condition of eating-out because the decision of consumers on whether to eat AFH or at home is determined by multiple non-linear socioeconomic factors. Here, we compared the carbon footprints of eating at home and AFH using household survey data from 12 Chinese provinces, and developed a Bayesian Belief Network (BBN) model to identify key factors of eating AFH. Our findings show that eating AFH leads to higher climatic burdens though respondents consume less food on average than when eating at home. However, in urban areas, the carbon footprint generated increases more rapidly from eating at-home than when eating AFH. The BBN model was found to have strong capability to predict the possibility of eating out with an accuracy of 89%. Although diet patterns and embedded carbon footprint vary considerably across provinces from northeastern to southwestern China, sufficient evidence could not be found to support the influence of geographic factors on the decision of respondents to eat AFH at large scale. Instead, individual occupation and income were found to be the two key contributors. Thus, merely estimating the carbon footprint of food consumption is currently not sufficient, but social and economic elements need to be quantitatively considered to differentiate the eating-place effect on diet-related climatic burden.

Mesolimbic connectivity signatures of impulsivity and BMI in early adolescence

Across age groups, differences in connectivity of the mesolimbic and the prefrontal cortex co-vary with trait impulsivity and sensation-seeking. Impulsivity and sensation-seeking are also known to increase during early adolescence as maturation of subcortical structures outpaces that of the prefrontal cortex. While an imbalance between the striatum and prefrontal cortex is considered a normal developmental process, higher levels of adolescent impulsivity and sensation-seeking are associated with an increased risk for diverse problems, including obesity. To determine how the relationship between sensation-seeking, impulsivity and body mass index (BMI) is related to shared neural correlates we measured their relationships with the connectivity of nuclei in the striatum and dopaminergic midbrain in young adolescents. Data were collected from 116 children between the ages of 12 and 14, and included resting state functional magnetic resonance imaging, personality measures from the Substance Use Risk Profile Scale, and BMI Z-score for age. The shared variance for the connectivity of regions of interest in the substantia nigra, ventral tegmental area, ventral striatum and sub-thalamic nucleus, personality measures and BMI Z-score for age, were analyzed using partial least squares correlation. This analysis identified a single significant striato-limbic network that was connected with the substantia nigra, ventral tegmental area and sub-thalamic nuclei (p = 0.002). Connectivity within this network which included the hippocampi, amygdalae, parahippocampal gyri and the regions of interest, correlated positively with impulsivity and BMI Z-score for age and negatively with sensation-seeking. Together, these findings emphasize that, in addition to the well-established role that frontostriatal circuits play in the development of adolescent personality traits, connectivity of limbic regions with the striatum and midbrain also impact impulsivity, sensation-seeking and BMI Z-score in adolescents.

Mix and Match: An Investigation into Whether Episodic Future Thinking Cues Need to Match Discounting Delays in Order to Be Effective

Episodic future thinking (EFT), or prospectively imagining yourself in the future, has been developed into an intervention tool to reduce delay discounting (DD), or the preference for smaller immediate over larger future rewards, and to make healthier choices that promote long-term health rather than short-term enjoyment. Most EFT interventions use EFT cues whose future events match the time delays of the DD task, which may limit the utility of EFT. The current study (N = 160, M_age = 35.25, 47.5% female) used a 2 × 2 factorial design with type of episodic thinking (matched, unmatched) and temporal perspective (EFT, episodic recent thinking (ERT)) as between-subject factors to investigate whether there were differences in DD for groups that had EFT cues matched to the time delays of the DD task in comparison to cues with unmatched temporal delays. The results showed EFT reduced DD compared to ERT controls, and no differences emerged between matched and unmatched EFT groups. Our findings suggest that either the process of generating EFT cues or the use of any positive and vivid future event, regardless of whether it is matched to the DD task, can reduce DD.

Delay discounting and its association with food purchasing considerations and food availability in the home in south-east Alabama, USA

Objective

Certain factors, such as food quality, label content and grocery characteristics, may be considered when purchasing foods. Food availability in the home has been shown to influence dietary behaviours, also associated with delay discounting (DD). The present study sought to characterize the relationships between DD, food purchasing considerations and healthfulness of foods in the home.

Design

A cross-sectional, online survey of adults (n 477) was conducted with the following measures: DD, consideration of food quality (nutrition, taste) and grocery characteristics (price, ease of preparation, shelf-life) while shopping, use of food labels and food availability in the home. DD was assessed by the area under the delay discounting curve (AUC) using a binary choice task. Greater AUC reflects lower DD. Structural equation modelling was used to allow AUC to simultaneously predict purchasing considerations and foods in the home.

Setting

Online survey.

Participants

Adult employees in south-east Alabama, USA.

Results

DD was negatively associated with food label use and emphasis on food quality when shopping (P<0·001). In the final model, DD was associated with availability of healthful foods in the home and emphasis on food quality and grocery characteristics. About 33 % of the variance in shopping behaviours, 5 % in food label use, 7 % in availability of healthful foods and 4 % in availability of unhealthful foods was explained by DD.

Conclusions

Individuals with lower DD appear to be more thoughtful in making food purchasing decisions and have healthful foods available in the home more frequently than individuals with higher DD.

Do process simulations during episodic future thinking enhance the reduction of delay discounting for middle income participants and those living in poverty?

Two studies examined whether episodic future thinking (EFT; pre-experiencing future events) reduces discounting of future rewards (DD). No studies have investigated whether process simulations (i.e., simulating the process of executing a future event) amplify EFT's reduction of DD. Study 1 examined the effect of incorporating process simulations into EFT (N = 42, M _age = 43.27; 91% female, family income = $75,976) using a 2 × 2 factorial design with type of episodic thinking (process, nonprocess/general) and temporal perspective (EFT, episodic recent thinking) as between-subjects factors. Study 2 replicated Study 1 in a sample of adults living in poverty (N = 36; M _age = 38.44, 88% female; family income = $25,625). The results of both studies showed EFT reduced DD, but process-oriented EFT did not amplify the effect of EFT. Our findings suggest the key ingredient in EFT's effect on DD is self-projection into the future. This was also the first study to show EFT improves DD in a sample living in poverty.

A multimodal investigation of impulsivity as a moderator of the relation between momentary elevations in negative internal states and subsequent dietary lapses

Suboptimal outcomes from behavioral weight loss (BWL) treatments are partially attributable to accumulated instances of non-adherence to dietary prescriptions (i.e., dietary lapses). Results identifying negative internal triggers for dietary lapses are inconsistent, potentially due to individual differences that impact how individuals respond to cues. Impulsivity is one factor that likely influences reactivity to internal states. We examined three dimensions of impulsivity (delay discounting, inhibitory control, and negative urgency) as moderators of the relation between affective and physical states and subsequent dietary lapses at the beginning of BWL. Overweight/obese adults (n = 189) completed behavioral and self-reported measures of impulsivity at baseline of BWL and an ecological momentary assessment (EMA) protocol across the first two weeks of treatment to report on affective/physical states and instances of dietary lapses. Results indicated that baseline negative urgency, but not delay discounting or inhibitory control, was positively associated with overall lapse risk. Moderation analyses indicated that poorer inhibitory control strengthened the relation between momentary increases in stress and subsequent dietary lapse, and higher negative urgency strengthened the relation between increases in loneliness and dietary lapse. Negative urgency also moderated the impact of momentary hunger on subsequent dietary lapse risk in an unexpected direction, such that higher negative urgency weakened the relation between hunger and subsequent lapse. Results lend partial and tentative support for the moderating role of impulsivity on the relation between internal states and lapse likelihood. With replication, the development and testing of personalized treatment components based on baseline impulsivity level may be warranted.

An examination of accuracy and bias in perceptions of a partner's motives for health behaviour regulation

OBJECTIVES

This study assessed accuracy and bias in people's perceptions of their romantic partner's adoption of short-term (avoid conflict) and long-term (later health) motives for interpersonally regulating their health behaviours.

DESIGN

A cross-sectional Web-based survey of 114 cohabiting romantic couples (N = 228 individuals) living in the United States.

METHODS

Romantic partners separately completed measures of their short-term and long-term motives for self-regulation and partner regulation of health behaviours, as well as their perceptions of partner regulation of their own health behaviours. Dyadic path analyses were conducted using the truth and bias model of judgement.

RESULTS

Targets of interpersonal regulation perceived their romantic partner's short-term and long-term motives for influencing their (the target's) health behaviour with significant accuracy. However, targets' perceptions of their partner's motives simultaneously contained about the same amount of projection of the target's own short- and long-term motives for self-regulation. There was no similarity between the target's motives for self-regulation and their partner's motives for interpersonal regulation. Targets also tended to underestimate their partner's long-term motives for interpersonal regulation.

CONCLUSIONS

Although people are somewhat accurate in their perceptions of their romantic partner's motives for attempting to influence their health behaviours, their perceptions are also contaminated by biases. This suggests that people's judgements about their partner's motives could be substantially improved. Statement of contribution What is known about this subject? Romantic partners use social influence tactics to improve each other's health behaviours. People who perceive their partner's influence attempts positively often make healthy changes. Misperceptions of a partner's motives for influence attempts may have health and relationship implications. What does this study add? People are aware of whether partner influence attempts are motivated by convenience or concern. People also project their own motives for self-regulating health behaviours onto their partner.

Leveraging delay discounting for health: Can time delays influence food choice?

Delay discounting, the tendency to choose smaller immediate rewards over larger delayed rewards, is theorized to promote consumption of immediately rewarding but unhealthy foods at the expense of long-term weight maintenance and nutritional health. An untested implication of delay discounting models of decision-making is that selectively delaying access to less healthy foods may promote selection of healthier (immediately available) alternatives, even if they may be less desirable. The current study tested this hypothesis by measuring healthy versus regular vending machine snack purchasing before and during the implementation of a 25-s time delay on the delivery of regular snacks. Purchasing was also examined under a $0.25 discount on healthy snacks, a $0.25 tax on regular snacks, and the combination of both pricing interventions with the 25-s time delay. Across 32,019 vending sales from three separate vending locations, the 25-s time delay increased healthy snack purchasing from 40.1% to 42.5%, which was comparable to the impact of a $0.25 discount (43.0%). Combining the delay and the discount had a roughly additive effect (46.0%). However, the strongest effects were seen under the $0.25 tax on regular snacks (53.7%) and the combination of the delay and the tax (50.2%). Intervention effects varied substantially between vending locations. Importantly, time delays did not harm overall vending sales or revenue, which is relevant to the real-world feasibility of this intervention. More investigation is needed to better understand how the impact of time delays on food choice varies across populations, evaluate the effects of time delays on beverage vending choices, and extend this approach to food choices in contexts other than vending machines.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02359916.

Effects of blood glucose on delay discounting, food intake and counterregulation in lean and obese men

BACKGROUND

Delay discounting as a measure of impulsivity has been shown to be higher in obesity with an association of increased food intake. Moreover, obese humans showed a higher wanting for high-calorie food than lean men when blood glucose concentrations were low. First studies linking blood glucose levels to delay discounting yielded mixed results. We hypothesized that obese people - in comparison to lean men - have a relative lack of energy, especially when blood glucose levels are low, that results in higher levels of delay discounting, food intake and hormonal counterregulation.

METHODS

We investigated 20 lean and 20 obese healthy young men in a single-blind balanced cross-over design. With a standardized glucose clamp technique, subjects underwent a hypoglycemic state in one condition and a euglycemic state in the control condition. Regularly, blood was sampled for assessment of hormonal status, and questionnaires were filled out to assess delay discounting and symptom awareness. After normalizing blood glucose concentrations, subjects were free to eat from a standardized test buffet, followed by a snack test.

RESULTS

Delay discounting was higher in obese than in lean men throughout experiments (p < 0.03). However, we did not observe significant discounting differences between glucose conditions (p > 0.1). Furthermore, the discounting performance did not correlate with food intake from the test buffet or snack test (p > 0.3). As a response to hypoglycemia, hormonal counterregulation was pronounced in both weight groups (p < 0.03), but responses of ACTH, norepinephrine and glucagon were stronger in obese compared to lean men (p < 0.03). Also, intake from the high-calorie buffet after hypoglycemia compared to euglycemia was higher in obese subjects (p < 0.02) but comparable in lean men (p > 0.5).

CONCLUSIONS

Our data suggest that augmented delay discounting is a robust feature in obesity that is not linked to glucose levels or actual food intake. With our systematically controlled approach, combining performance in delay discounting with regard to distinct blood glucose levels, different weight groups, counterregulatory behavior and food intake, our results imply that delay discounting is not susceptible to fluctuations of blood glucose and do not support the assumption that a low body's energy content leads to increased impulsivity. Further replications including women and larger sample sizes are needed to corroborate our data.

The value of instability: an investigation of intrasubject variability in brain activity among obese adolescent girls

BACKGROUND

The present study investigated the value of intrasubject variability (ISV) as a metric for revealing differences in cognition and brain activation associated with an obese versus lean body mass.

METHODS

Ninety-six adolescents with a lean body mass (body mass index (BMI) percentile=5-85), and 92 adolescents with an obese body mass (BMI percentile ⩾95), performed two tasks (Stroop and Go/No-Go) challenging response inhibition skills. The s.d. values and averages of their reaction time and P300 electroencephalographic responses to task stimuli were computed across trials.

RESULTS

During the Go/No-Go task, the reaction times of subjects with an obese body mass were more variable than those of their lean body mass peers. Accompanying the greater ISV in reaction times was a group difference in P300 amplitude ISV in the opposite direction across both tasks. The effect sizes associated with these group differences in ISV were marginally greater than the effect sizes for the comparisons of the group means.

CONCLUSIONS

ISV may be superior to the mean as a tool for differentiating groups without significant cognitive impairment. The co-occurrence of reduced ISV in P300 amplitude and elevated ISV in reaction time may indicate a constraint among obese adolescent girls in the range of information processing strategies and neural networks that can compete to optimize response output. It remains to be determined whether this decrement in neural plasticity has implications for their problem solving skills as well as their response to weight management interventions.

Impulsivity and temporal frame: Reducing frequency of snacking by highlighting immediate health benefits

The current study aimed to examine the effect of giving temporally framed health information regarding either the immediate or long-term health consequences of consuming high-calorie snacks, for people with high Negative Urgency (a dimension of impulsivity), and for those primed with impulsivity. We expected that for participants with high Negative Urgency, and those primed with impulsivity, information which detailed the immediate health benefits of avoiding snack consumption would be more effective than information which detailed long-term health benefits. Participants (N=110) completed a measure of Negative Urgency, reported their snacking frequency over the previous seven days, and completed either an impulsivity or neutral prime task. Following this, they read information detailing either the immediate or long-term health benefits of avoiding high-calorie snacks. High-calorie snack consumption was reported 7days later. The results showed a significant three-way interaction between Negative Urgency, prime task, and temporal frame. Participants who were primed with impulsivity and those high in Negative Urgency showed a greater reduction in snacking frequency after being given information about the immediate vs. long-term health benefits of snacking. The results suggest that the immediacy of health consequences should be considered when designing health information to reduce impulsive snacking behaviour.

Relative reinforcing value of food and delayed reward discounting in obesity and disordered eating: A systematic review

Understanding the food choice decision-making may help identify those at higher risk for excess weight gain and dysregulated eating patterns. This paper systematically reviews the literature related to eating behavior and behavioral economic constructs of relative reinforcing value of food (RRV_food) and delayed reward discounting (DRD). RRV_food characterizes how valuable energy-dense food is to the individual, and DRD characterizes preferences for smaller immediate rewards over larger future rewards, an index of impulsivity. Literature search on PubMed was conducted using combination of terms that involve behavioral economics and dysregulated eating in youth and adults. Forty-seven articles were reviewed. There is consistent evidence that obese youth and adults exhibit higher RRV_food. There is a need for more research on the role of RRV_food in eating disorders, as an insufficient number of studies exist to draw meaningful conclusions. There is accumulating evidence that obese individuals have higher DRD but the study of moderators of this relationship is crucial. Only a small number of studies have been conducted on DRD and binge eating, and no clear conclusions can be made currently. Approximately half of existing studies suggest lower DRD in individuals with anorexia nervosa. Research implications and treatment application are discussed.

Not so fast: The impact of impulsivity on weight loss varies by treatment type

Behavioral weight loss (BWL) treatments result in suboptimal weight losses for many individuals. Impulsivity appears to be a maintenance factor of obesity, yet few studies have examined impulsivity as a predictor of outcomes from BWL. We examined specific facets of impulsivity (inhibitory control and delay discounting) as moderators of outcome in BWL. Overweight adults (n = 190) were randomized to standard behavioral treatment (SBT) or acceptance-based behavioral treatment (ABT). We hypothesized that impulsivity would be inversely associated with weight loss, and that the association between impulsivity and outcome would be attenuated in the ABT condition. Poorer general inhibitory control predicted lower percent weight lost at 12 months across conditions at the trend level (b = -0.003, p = 0.06). The negative impact of low inhibitory control on weight loss was attenuated by assignment to ABT versus SBT (b = 0.004, p = 0.03). Treatment condition, at trend level, also moderated the impact of delay discounting (b = -0.011, p = .098) and food-specific inhibitory control (b = 0.003, p = 0.06) on percent weight loss such that those with greater impulsivity benefitted most from ABT. Results reveal a potential pattern that impulsivity reduces benefit derived from SBT but not ABT. Further research on the moderating effect of impulsivity is necessary to inform the development of targeted treatments for clinically meaningful subtypes of patients.

Economic preferences and fast food consumption in US adults: Insights from behavioral economics

OBJECTIVE

To examine the relationship between economic time preferences and frequency of fast food and full-service restaurant consumption among U.S. adults.

METHODS

Participants included 5871U.S. adults who responded to a survey conducted in 2011 pertaining to the lifestyle behaviors of families and the social context of these behaviors. The primary independent variable was a measure of time preferences, an intertemporal choice assessing delay discounting. This was elicited via responses to preferences for an immediate dollar amount or a larger sum in 30 (30-day time horizon) or 60days (60-day time horizon). Outcomes were the frequency of fast food and full-service restaurant consumption. Ordered logistic regression was performed to examine the relationship between time preferences and food consumption while adjusting for covariates (e.g. socio-demographics).

RESULTS

Multivariable analysis revealed that higher future time preferences were significantly related to less frequent fast food intake for both the 30- and 60-day time horizon variables (P for linear trend <0.05; both). Notably, participants with the highest future time preference were significantly less likely to consume fast food than those with very low future time preferences (30-day: OR=0.74, 95%CI: 0.62-0.89; and 60-day: OR=0.86, 95%CI: 0.74-1.00). In comparison, higher future time preferences were not significantly associated with full-service restaurant intake (30-day: p for linear trend=0.73; 60-day: p for linear trend=0.83).

CONCLUSIONS

Higher future time preferences were related to a lower frequency of fast food consumption. Utilizing concepts from behavioral economics (e.g. pre-commitment contracts) to facilitate more healthful eating is warranted using experimental studies.

Unhealthy diets, obesity and time discounting: a systematic literature review and network analysis

There is an increasing policy commitment to address the avoidable burdens of unhealthy diet, overweight and obesity. However, to design effective policies, it is important to understand why people make unhealthy dietary choices. Research from behavioural economics suggests a critical role for time discounting, which describes how people's value of a reward, such as better health, decreases with delay to its receipt. We systematically reviewed the literature on the relationship of time discounting with unhealthy diets, overweight and obesity in Web of Science and PubMed. We identified 41 studies that met our inclusion criteria as they examined the association between time discount rates and (i) unhealthy food consumption; (ii) overweight and (iii) response to dietary and weight loss interventions. Nineteen out of 25 cross-sectional studies found time discount rates positively associated with overweight, obesity and unhealthy diets. Experimental studies indicated that lower time discounting was associated with greater weight loss. Findings varied by how time discount rates were measured; stronger results were observed for food than monetary-based measurements. Network co-citation analysis revealed a concentration of research in nutrition journals. Overall, there is moderate evidence that high time discounting is a significant risk factor for unhealthy diets, overweight and obesity and may serve as an important target for intervention. © 2016 The Authors Obesity Reviews published by John Wiley & Sons Ltd on behalf of International Association for the Study of Obesity (IASO).

To work or not to work: Neural representation of cost and benefit of instrumental action

By definition, instrumental actions are performed in order to obtain certain goals. Nevertheless, the attainment of goals typically implies obstacles, and response vigor is known to reflect an integration of subjective benefit and cost. Whereas several brain regions have been associated with cost/benefit ratio decision-making, trial-by-trial fluctuations in motivation are not well understood. We review recent evidence supporting the motivational implications of signal fluctuations in the mesocorticolimbic system. As an extension of "set-point" theories of instrumental action, we propose that response vigor is determined by a rapid integration of brain signals that reflect value and cost on a trial-by-trial basis giving rise to an online estimate of utility. Critically, we posit that fluctuations in key nodes of the network can predict deviations in response vigor and that variability in instrumental behavior can be accounted for by models devised from optimal control theory, which incorporate the effortful control of noise. Notwithstanding, the post hoc analysis of signaling dynamics has caveats that can effectively be addressed in future research with the help of two novel fMRI imaging techniques. First, adaptive fMRI paradigms can be used to establish a time-order relationship, which is a prerequisite for causality, by using observed signal fluctuations as triggers for stimulus presentation. Second, real-time fMRI neurofeedback can be employed to induce predefined brain states that may facilitate benefit or cost aspects of instrumental actions. Ultimately, understanding temporal dynamics in brain networks subserving response vigor holds the promise for targeted interventions that could help to readjust the motivational balance of behavior.

Steep discounting of delayed monetary and food rewards in obesity: a meta-analysis

BACKGROUND

An increasing number of studies have investigated delay discounting (DD) in relation to obesity, but with mixed findings. This meta-analysis synthesized the literature on the relationship between monetary and food DD and obesity, with three objectives: (1) to characterize the relationship between DD and obesity in both case-control comparisons and continuous designs; (2) to examine potential moderators, including case-control v. continuous design, money v. food rewards, sample sex distribution, and sample age (18 years); and (3) to evaluate publication bias.

METHOD

From 134 candidate articles, 39 independent investigations yielded 29 case-control and 30 continuous comparisons (total n = 10 278). Random-effects meta-analysis was conducted using Cohen's d as the effect size. Publication bias was evaluated using fail-safe N, Begg-Mazumdar and Egger tests, meta-regression of publication year and effect size, and imputation of missing studies.

RESULTS

The primary analysis revealed a medium effect size across studies that was highly statistically significant (d = 0.43, p < 10-14). None of the moderators examined yielded statistically significant differences, although notably larger effect sizes were found for studies with case-control designs, food rewards and child/adolescent samples. Limited evidence of publication bias was present, although the Begg-Mazumdar test and meta-regression suggested a slightly diminishing effect size over time.

CONCLUSIONS

Steep DD of food and money appears to be a robust feature of obesity that is relatively consistent across the DD assessment methodologies and study designs examined. These findings are discussed in the context of research on DD in drug addiction, the neural bases of DD in obesity, and potential clinical applications.

Errors as a Means of Reducing Impulsive Food Choice

Nowadays, the increasing incidence of eating disorders due to poor self-control has given rise to increased obesity and other chronic weight problems, and ultimately, to reduced life expectancy. The capacity to refrain from automatic responses is usually high in situations in which making errors is highly likely. The protocol described here aims at reducing imprudent preference in women during hypothetical intertemporal choices about appetitive food by associating it with errors. First, participants undergo an error task where two different edible stimuli are associated with two different error likelihoods (high and low). Second, they make intertemporal choices about the two edible stimuli, separately. As a result, this method decreases the discount rate for future amounts of the edible reward that cued higher error likelihood, selectively. This effect is under the influence of the self-reported hunger level. The present protocol demonstrates that errors, well known as motivationally salient events, can induce the recruitment of cognitive control, thus being ultimately useful in reducing impatient choices for edible commodities.

The utility of behavioral economics in expanding the free-feed model of obesity

Animal models of obesity are numerous and diverse in terms of identifying specific neural and peripheral mechanisms related to obesity; however, they are limited when it comes to behavior. The standard behavioral measure of food intake in most animal models occurs in a free-feeding environment. While easy and cost-effective for the researcher, the free-feeding environment omits some of the most important features of obesity-related food consumption-namely, properties of food availability, such as effort and delay to obtaining food. Behavior economics expands behavioral measures of obesity animal models by identifying such behavioral mechanisms. First, economic demand analysis allows researchers to understand the role of effort in food procurement, and how physiological and neural mechanisms are related. Second, studies on delay discounting contribute to a growing literature that shows that sensitivity to delayed food- and food-related outcomes is likely a fundamental process of obesity. Together, these data expand the animal model in a manner that better characterizes how environmental factors influence food consumption.

The relation of hedonic hunger and restrained eating to lateralized frontal activation

Asymmetrical alpha activation in the prefrontal cortex (frontal asymmetry) in electroencephalography (EEG) has been related to eating behavior. Prior studies linked dietary restraint with right frontal asymmetry [1] and disinhibition with left frontal asymmetry [2]. The current study simultaneously assessed restrained eating and hedonic hunger (drive for food reward in the absence of hunger) in relation to frontal asymmetry. Resting-state EEG and measures of restrained eating (Revised Restraint Scale; RRS) and hedonic hunger (Power of Food Scale; PFS) were assessed in 61 non-obese adults. Individually, hedonic hunger predicted left asymmetry. However, PFS and RRS were correlated (r=0.48, p<0.05) and there was a significant interaction between PFS and RRS on frontal asymmetry, p<0.01. Results indicated that those high in hedonic hunger exhibited left asymmetry irrespective of RRS scores; among those low in PFS, only those high in RRS showed right asymmetry. Results were consistent with literature linking avoidant behaviors (restraint) with right-frontal asymmetry and approach behaviors (binge eating) with left-frontal asymmetry. It appears that a strong drive toward palatable foods predominates at a neural level even when restraint is high. Findings suggest that lateralized frontal activity is an indicator of motivation both to consume and to avoid consuming highly palatable foods.

The reinforcing value of palatable snack foods and its relationship to subtypes of behavioural and self-report impulsivity

Data collected over the last decade has begun to implicate behavioural impulsivity in overeating behaviour. However, recent work has suggested that the reinforcing value of food may be associated with impulsive choice (a sub-type of impulsivity), but to date no study has examined how the reinforcing value of food relates to other aspects of impulsivity. To examine these inter-relationships, 80 women completed measures of eating (a snack intake test and the Three-Factor Eating Questionnaire and then in a separate test session an inhibitory control task, a delay discounting task, a reflection impulsivity task, and a measure of the reinforcing value of their chosen snack foods. Participants also completed the Behavioural Inhibition System/Behavioural Activation System (BIS/BAS) questionnaire to examine self-report and behavioural parallels between measures. In regression models, only Behavioural Inhibition System subscales of the BIS/BAS predicted increased responding on the reinforcing value of food task. The reinforcing value of food task predicted and trended to predict calorie and grams intake of snack foods in regression models, supporting RRV as a predictive measure of short-term snack intake. Likewise, impulsive choice and inhibitory control was not related to eating measures. Methodological implications are discussed.