Competing Revision: Sensitization of the Reinforcing Value of Food as a Predictor of Weight Change in Adolescents.

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Project Summary: The adolescent brain is driven to seek out reinforcers, but the areas of the brain involved in impulse control and executive function remain immature until early adulthood. This may make adolescents particularly susceptible to overeating and weight gain. Motivation to eat, or reinforcing value (RRV) of food, is a strong predictor of energy consumption and adiposity. Understanding factors that lead to higher levels of the RRV of food is a critical first step toward developing novel treatment and prevention strategies for obesity. The purpose of the parent grant was 1) to determine if increases in the RRV of high energy density snack foods predict weight gain over time 2) to determine if increases in the RRV of low energy density snacks protect against weight gain over time 3) to determine if RRV of physical activity and/or delay discounting (DD) moderate the relationship between changes in the RRV of food after repeated exposure and weight change in adolescents. We have completed baseline data collection on 95% of our target sample in the parent grant as well as follow-up appointments on approximately 50% of our target population. We have shown that children with healthy weight decrease their RRV of snack food after two weeks of repeated exposure, but children with overweight do not show changes in RRV of snack food after repeated exposure. We have also shown that participants who showed an increase in RRV of snack food after repeated exposure had significantly greater zBMI change at 6 and 15 months compared to those participants who did not increase their RRV of food. Finally, we showed that individuals with high baseline RRV and DD had significantly greater zBMI change at 6 and 15 months compared to those with low DD and RRV of food. When taken together, these findings suggest that several behavioral phenotypes predict zBMI change over time and could potentially help to identify individuals at high risk of weight gain prior to the onset of weight gain. While we work toward completion of the original goals of the parent grant, new ideas have emerged as we have progressed through this study. The primary purpose of this competing revision proposal is to build upon our preliminary findings and determine 1) if the predictive value of baseline behavioral phenotypes extends into later adolescence 2) the role that eating autonomy plays in eating behavior and weight change over time 3) the extent to which the development of disordered eating behavior and dieting moderates the relationship between baseline behavioral phenotypes and zBMI change over time. This competing revision proposal will enhance the value of the outcomes of the parent grant by adding additional, age-appropriate measures, by extending the timeline of our follow- up to later adolescence and emerging adulthood, and by allowing us to develop and validate a novel measure of eating behavior (eating autonomy) that may be particularly important during this critical period of eating behavior development. Once these factors are identified and characterized, future studies could focus on refining methods for altering the RRV of food as a way to increase healthy eating and decrease less healthy food intake.