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 (ß = 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.

Eating and Physical Activity Patterns in Day and Night Shift EMS Clinicians.

Objective: EMS clinicians work in shifts to provide 24-hour care. Shift work is linked with metabolic disease and over 70% of EMS clinicians report having overweight or obesity. Inability to store food in their vehicles combined with limited overnight dining establishments, and unpredictable job demands leads to reliance on convenience and fast foods. The objective of this study was to describe the eating and physical activity patterns among EMS clinicians on days on and off shift.Methods: EMS clinicians throughout the United States participated in a study involving four 24-hour monitoring periods. Participants wore activity monitors to measure physical activity level and remote food photography was used to collect dietary data on two work days and two days off. Repeated measures analysis of variance was conducted to compare energy and macronutrient intake and activity levels in day and night workers on and off shift.Results: We analyzed data from 39 EMS clinicians (29.7 + 8.5yrs old). Controlling for sex, those working night shifts consumed more kilocalories (p=.037) and total fat (p=.043) compared to day shift workers. Night shift workers had fewer steps (p = 0.045), more sedentary time (p = 0.053), and less moderate activity (p = 0.037) during a shift compared to day workers.Conclusion: Among EMS clinicians, night shift is associated with greater energy intake, and decreased physical activity during shifts. This may contribute to positive energy balance and weight gain overtime, increasing risk for metabolic disease.

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

BACKGROUND: In the United states obesity and socioeconomic status (SES), or one's standing in society based on income, education, and/or occupation, are strongly associated. The mechanisms for this relationship may include having high levels of motivation to get food (reinforcing value of food; RRV) and low levels of inhibitory control (delay discounting; DD) which, when combined, is referred to as reinforcement pathology (RP). We sought to examine the relationships among multiple measures of household SES, RP, and age-adjusted body mass index (zBMI) among adolescents. METHODS: These data were collected as part of ongoing longitudinal study of risk factors for obesity in 244 adolescents. The adolescents and one parent/guardian had height and weight measured and completed surveys. The adolescents completed an adjusting amount DD task and a computer-based RRV task. Analyses consisted of correlations among measures of SES and RRV, DD, and BMI z-scores. In the case of significant associations, multiple regression models were created with theoretically informed covariates. RESULTS: Household income, parent/guardian education, parent/guardian occupation, and food insecurity status were all related to one another. Among the adolescents, a significant portion of the variance in RRV was accounted for by household income after controlling for covariates. For DD, it was parent/guardian education that was most associated after controlling for covariates. CONCLUSION: When low income and low parent/guardian education occur together, there may be an increased risk of RP. Separately, food insecurity was predictive of higher parent/guardian BMI. Future research should continue to explore the effects of low income and parent/guardian education on RP among youth by examining them over time.

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 to 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.

The Impact Plant-Based Diets Have on Athletic Performance and Body Composition: A Systematic Review.

Plant-based diets have gained popularity among athletes in recent years. Some believe that plant-based diets will improve performance owing to higher intakes of carbohydrates and antioxidants. Some believe it that will harm performance due to lower intakes of complete protein and creatine. This systemic review was conducted using Covidence software. A literature search of PubMed, Embase (Elsevier), CINAHL Plus (EBSCO), and Web of Science was completed on 22 March 2022. Following the development of clear objectives and a research question that identified the population, intervention, comparison, and outcomes, initial search criteria and keywords were identified. Extracted results totaled 2249, including 797 duplicates. The initial screening resulted in 1437 articles being excluded. The remaining 15 articles proceeded to full-text screening. A final 8 articles were included in the review, with 7 excluded. This paper will review the impact plant-based diets have on athletic performance and body composition in healthy young adults aged 18 to 45 years.

Following a plant-based diet does not harm athletic performance.Plant-based diets may improve maximal oxygen consumption, vertical countermovement jumps, and relative strength.There is no evidence that plant-based diets are detrimental to athletic performance or body composition.The long-term implications and the affect following a plant-based diet has on athletic performance in professional athletes are still unknown.

The Influence of Relative Reinforcing Value of Food, Sensitization, Energy Intake and Diet Quality on zBMI Change over Two Years in Adolescents: A Longitudinal Cohort Study.

The relative reinforcing value (RRV) of food and sensitization are associated with zBMI and zBMI change over time, but the mechanisms underlying these relationships is unknown. The purpose of this study was to test the hypothesis that greater RRV and sensitization to HED food is associated with lower diet quality and greater energy intake at baseline and again at 24 months and that these relationships result in greater zBMI gain. The RRV of HED and LED food and dietary intake were measured at baseline and again after 24 months in a cohort of 202 boys and girls of 12-14 years old. The baseline RRV of HED food was associated with lower diet quality and lower energy intake at 24 months. zBMI gain was positively associated with the baseline energy intake but not baseline RRV of HED food or diet quality. However, diet quality moderated the relationship between baseline energy intake and zBMI change, with no difference in zBMI change as a function of energy intake when diet quality was high but significant and opposite relationships with energy intake when diet quality was low. This study suggests that high diet quality can reduce the negative impact of greater energy intake on zBMI change in adolescents.

Eating Patterns among Emergency Medical Service Providers in the United States: A Qualitative Interview Study.

Emergency medical service (EMS) providers experience demanding work conditions in addition to shift work, which increases risk for nutrition related chronic disease such as metabolic syndrome, diabetes, obesity, and cardiovascular disease. The high stress, emergent, and unpredictable nature of EMS may interfere with healthy eating patterns on and off shift, however little is known about how these conditions impact dietary patterns among EMS providers. This study aimed to understand factors impacting dietary patterns through semi-structured interviews with 40 EMS providers throughout the United States. Interviews were conducted virtually via Zoom video conference. Inductive coding was used to identify themes throughout the interviews. Salient factors mentioned in the interviews included hunger, fatigue, stress, coworker influence, ambulance posting, geographical location, agency policy, and culture. Factors were grouped into 4 domains: physiological factors, psychosocial factors, physical environment, and organizational environment, represented by an adapted version of the social ecological model of health behaviors to include factors influencing eating patterns specific to EMS, which may contribute to overall health. Various barriers to healthy eating exist within EMS, and future studies should explore interventions at each level of our proposed model to improve conditions and reduce nutrition related disease risk in this essential population.

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.

An Ecological Perspective of Food Choice and Eating Autonomy Among Adolescents.

Adolescence is an important developmental period marked by a transition from primarily parental-controlled eating to self-directed and peer-influenced eating. During this period, adolescents gain autonomy over their individual food choices and eating behavior in general. While parent-feeding practices have been shown to influence eating behaviors in children, little is known about how these relationships track across adolescent development as autonomy expands. The purpose of this qualitative study was to identify factors that impact food decisions and eating autonomy among adolescents. Using the food choice process model as a guide, four focus groups were conducted with 34 adolescents. Focus group discussion was semi-structured, asking teens about influences on their food choices across different food environments, their involvement with food purchasing and preparation, and perceived control over food their choices. Focus group transcripts were analyzed using deductive and inductive code creation and thematic analysis. This study found six leading influences on adolescents' food choices and identified additional factors with prominence within specific environmental contexts. This study distinguished a broader spectrum of factors influencing adolescent food choice that extend beyond "convenience" and "taste" which have previously been identified as significant contributors. The degree of control that teens reported differed by eating location, occasion, and social context. Finally, adolescents demonstrated various levels of engagement in behaviors related to their eating autonomy. Identifying the emergent themes related to adolescent autonomy was the first step toward the goal of developing a scale to evaluate adolescent eating autonomy.