Behavioral sensitization of the reinforcing value of food: What food and drugs have in common

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.

Highly processed foods can be considered addictive substances based on established scientific criteria

BACKGROUND

There is growing evidence that an addictive-eating phenotype may exist. There is significant debate regarding whether highly processed foods (HPFs; foods with refined carbohydrates and/or added fats) are addictive. The lack of scientifically grounded criteria to evaluate the addictive nature of HPFs has hindered the resolution of this debate.

ANALYSIS

The most recent scientific debate regarding a substance's addictive potential centered around tobacco. In 1988, the Surgeon General issued a report identifying tobacco products as addictive based on three primary scientific criteria: their ability to (1) cause highly controlled or compulsive use, (2) cause psychoactive (i.e. mood-altering) effects via their effect on the brain and (3) reinforce behavior. Scientific advances have now identified the ability of tobacco products to (4) trigger strong urges or craving as another important indicator of addictive potential. Here, we propose that these four criteria provide scientifically valid benchmarks that can be used to evaluate the addictiveness of HPFs. Then, we review the evidence regarding whether HPFs meet each criterion. Finally, we consider the implications of labeling HPFs as addictive.

CONCLUSION

Highly processed foods (HPFs) can meet the criteria to be labeled as addictive substances using the standards set for tobacco products. The addictive potential of HPFs may be a key factor contributing to the high public health costs associated with a food environment dominated by cheap, accessible and heavily marketed HPFs.

Hyperpalatable Foods Consumption in a Representative Sample of the General Population in Brazil: Differences of Binge and Non-Binge Eating Meals

The availability of hyper-palatable foods (HPF) increased over the past three decades worldwide, a period when eating disorders (ED) and obesity have become global public health concerns. The present study aimed to assess HPF consumption during binge and non-binge meals in a representative sample of adults with and without ED from a metropolitan city in Brazil. A total of 2297 individuals were interviewed in their homes by trained lay interviewers to assess the presence of binge eating disorder (BED), bulimia nervosa (BN), and recurrent binge eating (RBE). Information on their food consumption in objective and subjective binge eating episodes (OBE and SBE, respectively), as well as in the 24 h food recall were obtained. Individuals from the general population consumed 56% of their total calories from HPF. In non-binge meals, people with BN consumed substantially fewer calories from HPF than BED (63% vs. 48%) and RBE (63% vs. 48%) groups. During OBE, participants consumed an average of 70% of the calories from HPF, with no between-group differences. During SBE, subjects with BN consumed substantially fewer calories from HPF than those with BED (76% vs. 50%). In conclusion, HPF were highly consumed by the Brazilian population. However, there was a greater impact on BED and RBE subjects and during binge eating episodes.

Validation and Psychological Properties of the Persian Version of DSM 5 Yale Food Addiction Scale 2.0 (PYFAS 2.0) in Non-clinical Population

Background

The Yale Food Addiction Scale version 2.0 (YFAS 2.0) is used for the assessment of food addiction (FA). This research intended to evaluate the validity of the Persian translation of the questionnaire and to investigate the psychological properties and the association between FA and anthropometric indices.

Methods

In a sample of 473 nonclinical participants, FA, binge eating, and objectively measured anthropometric indices were assessed. Internal consistency, convergent, and validity of the PYFAS 2.0 were examined. Also, the factor structure (confirmatory factor analysis following the 11 diagnostic indicators in addition to the significant distress) and the construct of the scale were evaluated.

Findings

The frequencies of mild, moderate, and severe FA based on PYFAS 2.0 were 0.2%, 10%, and 5.5%, respectively. The findings supported a one-factor structure. The confirmatory factor analysis revealed a good construct validity (RMSEA=0.043, χ²=76.38, df=41, χ² (CMIN)/df=1.862, GFI=0.975, AGFI=0.957, IFI=0.986, RFI=0.958, ECVI=0.319, TLI=0.978). For both the diagnostic and symptom count versions, the PYFAS 2.0 presented acceptable internal consistency (IC) (Kuder-Richardson 20=0.99 and McDonald omega=0.91).

Conclusion

The PYFAS 2.0 was a psychometrically sound instrument in an Iranian non-clinical population. This questionnaire can be used to study FA in Persian non-clinical populations. Future research should study the psychometric characteristics of this scale in high-risk groups.

Hyper-palatable food consumption during binge-eating episodes: A comparison of intake during binge eating and restricting

OBJECTIVE

The study aim was to elucidate the degree to which hyper-palatable foods (HPF) are consumed during binge episodes compared to restricting episodes, and to test the association between HPF intake during each episode and respective episode frequency.

METHOD

This study was a secondary analysis of data from a larger study on eating disorders. The present sample included adults (N = 147, 83% women) diagnosed with sub-threshold (41%) or full-threshold (59%) bulimia nervosa (BN). Foods consumed during binge and restricting episodes were assessed using the Eating Pathology Symptoms Inventory-Clinician Rated Version. A standardized definition of HPF developed previously was applied to foods consumed during binge and restricting episodes. A Wilcoxon matched-pairs signed-rank test was used to test the difference between total caloric intake from HPF (KcalHPF) and percentage of caloric intake from HPF (PercHPF) during binge episodes relative to restricting episodes. Four linear regression models tested HPF intake (KcalHPF and PercHPF) during both episode types (binge and restricting) as predictors of respective episode frequency.

RESULTS

There was a significant difference between median KcalHPF (1846.6 vs. 279.6; Z = -13.38, p < .001) and PercHPF during binge compared to restricting episodes (95% vs. 61%; Z = -7.35, p < .001). Regression analyses demonstrated that KcalHPF during binge episodes was significantly associated with binge episode frequency (B = 0.002; p < .001), but not PercHPF (p = .287).

DISCUSSION

Results suggest that HPF may be primarily consumed during binge episodes among individuals with BN, and may be associated with greater binge-eating frequency.

PUBLIC SIGNIFICANCE

Findings from the current study support an underlying assumption of theoretical models of binge eating, suggesting that highly rewarding, hyper-palatable foods (HPF), may constitute the vast majority of energy intake during binge-eating episodes. Additionally, a substantial amount of energy intake from HPF may occur during restricting episodes among people with bulimia nervosa. Greater HPF intake during binge eating may also be associated with binge-eating severity.

Sensitization of the reinforcing value of high energy density foods is associated with increased zBMI gain in adolescents

Background/Objectives

Characterizing behavioral phenotypes that predict increased zBMI gain during adolescence could identify novel intervention targets and prevent the development of obesity. The purpose of this study was to determine if sensitization of the relative reinforcing value (RRV) of high (HED) or low energy density (LED) foods predicts adolescent weight gain trajectories. A secondary aim was to test the hypothesis that relationships between sensitization of the RRV of food and weight change are moderated by delay discounting (DD).

Subjects/Methods

We conducted a prospective, longitudinal cohort study in 201 boys and girls with an average zBMI of 0.4, who began the study between the ages of 12 and 14 years and completed the study 2 years later. Participants completed five laboratory visits where the RRV of HED and LED, and DD were assessed at a baseline (visits 1, 2, and 4) and then RRV was measured again after participants consumed a portion of the same HED and LED food for 2 weeks (visits 3 and 5; order counterbalanced). Increases (>1) in the RRV from baseline to post-daily intake were categorized as “sensitization” and decreases (≤1) were categorized as “satiation.” Participants returned to the laboratory for follow-up visits at 6, 15, and 24 months to have height and weight taken and to complete additional assessments.

Results

Sensitization to HED food was associated with a greater zBMI change over time (β = 0.0070; p = 0.035). There was no impact of sensitization to LED food or interaction between sensitization to HED and LED food on zBMI change and no moderation of DD on the relationship between HED sensitization and zBMI change (all p > 0.05).

Conclusion

Our prior work showed that sensitization to HED food is cross-sectionally associated with greater zBMI. This study extends this work by demonstrating that sensitization to HED food prospectively predicts increased zBMI gain over time in adolescents without obesity. Future studies should determine if sensitization can be modified or reduced through behavioral intervention.

Trial registration

Clinicaltrials.gov: NCT04027608.

Perceived Intensity and Palatability of Fatty Culinary Preparations is Associated with Individual Fatty Acid Detection Threshold and the Fatty Acid Profile of Oils Used as Ingredients

The term oleogustus was recently proposed to describe a sixth basic taste that could guide preference for fatty foods and dishes to an extent. However, experimental data on food preference based on fatty acid (FA) content is scarce. Our aim was to examine the role of FA profile of oils and preparations as well as FA sensory thresholds on the palatability of salty and sweet culinary preparations representative of traditional Spanish Mediterranean cooking. In this study, we used three oils with similar texture and odor profile but different in their FA composition (saturated, monounsaturated, and polyunsaturated) and compared subjects in regard to their FA detection threshold and perceived pleasantness and intensity. Our results indicate that whereas saturated FAs cannot be detected at physiological concentrations, individuals can be categorized as tasters and nontasters, according to their sensory threshold to linoleic acid, which is negatively associated with perceived intensity (r = -0.393, P < 0.001) but positively with palatability (r = 0.246, P = 0.018). These differences may be due to a possible response to a fat taste. This sixth taste, or oleogustus. would allow establishing differences in taste intensity/palatability considering the FA profile of the culinary preparations. Given that tasters can detect linoleic and oleic acid at lower concentrations than nontasters, a greater amount of unsaturated FAs in culinary preparations could provoke an unpleasant experience. This finding could be relevant in the context of the culinary sector and to further our understanding of food preference and eating behavior.

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.

Substance Use and Obesity Trajectories in African Americans Entering Adulthood

INTRODUCTION

The transition to adulthood can be stressful for minority adolescents, and many may cope through unhealthy behaviors, including substance use and obesity-related behaviors. This study tested substance use and obesity trajectories over time in African American youth, longitudinal associations of trajectories with mental and physical health in adulthood, and whether self-control and sex predict trajectories.

METHODS

Two longitudinal studies of 516 and 992 African American adolescents. In Study 1, substance use and obesity trajectories were assessed from ages 19 to 25 years. At age 25 years, internalizing and externalizing problems, metabolic syndrome, and inflammatory biomarkers were measured. In Study 2, substance use and obesity trajectories were assessed from ages 17 to 29 years. Depression, delinquency, diabetes, blood pressure, and inflammatory biomarkers were measured at age 29 years. Data analyses were conducted in 2017.

RESULTS

Across both studies, the majority of African American adolescents evinced poor health behavior trajectories (latent class growth analyses), with 23%-27% showing increasing substance use over time, 18%-27% showing increasing obesity over time, and 9%-11% showing increases in both. ANCOVAs for trajectory analyses revealed that males were more likely to evince increasing substance use, with females more likely to show increasing obesity. Substance use trajectories were associated with poorer mental health in adulthood; obesity trajectories with poorer physical health in adulthood. Those with good health behavior trajectories had higher self-control in early adolescence.

CONCLUSIONS

The transition to adulthood is a vulnerable period for many African Americans. Given the commonalities of substance use and obesity in their rewarding/stress-relieving properties, similar prevention efforts may help stem the rise of both in these youth.

Reinforcing Value of Caffeinated and Noncaffeinated Beverages After Acute Exposure in Children and Adolescents

Background: When caffeine is added to beverages, it increases beverage liking and the relative reinforcing value (RRV) of these beverages after repeated exposure. The purpose of this study was to test the hypothesis that a single acute exposure to caffeine increases liking and motivation to consume sugar-sweetened beverages (SSBs) relative to placebo. Methods: Participants were children ages 8-9 years (n = 36) and adolescents ages 15-17 years (n = 41) with an approximately equal number of boys and girls. A double-blind, placebo-controlled crossover study was conducted where participants sampled a SSB containing caffeine (1 and 2 mg/kg) on one visit and placebo (quinine 0.01 and 0.02 mg/kg) on a second visit day and then, on a third visit, played a computer game to earn points for the beverages and rated liking and taste sensations. They returned to the laboratory after a 1-week washout and had the alternate dose combination. Results: Acute exposure to the higher dose of caffeine increased the RRV of the SSB relative to placebo, but only when that dose was presented in the first week and only in female participants. The liking of the caffeine-containing SSB at the higher dose was lower than the placebo at all time points. Conclusions: These data suggest that a single exposure to a caffeinated SSB can impact its RRV and liking, but only under certain conditions and only in females. This supports previous work suggesting that caffeine can increase desire to consume SSB.

Daily exposure to either a high- or low-energy-dense snack food reduces its reinforcing value in adolescents

OBJECTIVE

To examine the impact of daily exposure to a low-energy-dense (LED) or a high-energy-dense (HED) snack food on its reinforcing value (RRV) in adolescents with healthy weight, overweight, or obesity.

METHODS

A parallel-group, randomized trial was used to assess RRV of LED or HED snack food at baseline and again after exposure to that snack food daily for 2 weeks in 77 adolescents, aged 13 to 17 years. Information on eating-related subject characteristics was also collected at baseline.

RESULTS

After 2 weeks of daily exposure, the RRV of the snack foods was significantly reduced in all participants, regardless of energy density or participant weight status. Among individuals who were high in dietary restraint only, those randomized to LED food found their snack food less reinforcing at baseline than those who were randomized to HED food. Baseline eating-related variables also differed as a function of weight status.

CONCLUSIONS

Daily exposure to snack food in adolescents reduces the RRV of that food regardless of snack food energy density or weight status of the adolescent. This finding differs from adults, suggesting that increases in RRV of HED food after repeated exposure may develop after adolescence.

Editorial: 3rd Special Issue on behavior change, health, and health disparities

This Special Issue of Preventive Medicine (PM) is the 3rd that we have organized on behavior change, health, and health disparities. This is a topic of critical importance to improving U.S. population health. There is broad scientific consensus that personal behaviors such as cigarette smoking, other substance abuse, and physical inactivity/obesity are among the most important modifiable causes of chronic disease and its adverse impacts on population health. Hence, effectively promoting health-related behavior change needs to be a key component of health care research and policy. There is also broad recognition that while these problems extend throughout the population, they disproportionately impact economically disadvantaged populations and other vulnerable populations and represent a major contributor to health disparities. Thus, behavior change represents an essential step in curtailing health disparities, which receives special attention in this 3rd Special Issue. We also devote considerable space to the longstanding challenges of reducing cigarette smoking and use of other tobacco and nicotine delivery products in vulnerable populations, obesity, and for the first time food insecurity. Across each of these topics we include contributions from highly accomplished policymakers and scientists to acquaint readers with recent accomplishments as well as remaining knowledge gaps and challenges.