Effectiveness Trial of a Dissonance-Based Obesity Prevention Program

Overview

Obesity is a major US public health problem. Few obesity prevention programs have reduced risk for weight gain over follow-up and those that have are very intensive, making dissemination difficult and costly. A brief 3-hr selective prevention program (Healthy Weight) targeting young adults with body dissatisfaction involving participant-driven healthy dietary and physical activity lifestyle changes significantly reduced increases in body mass index (BMI) and obesity onset relative to alternative interventions and assessment-only controls through 3-yr follow-up, though effects were small in magnitude. To enhance efficacy, the investigators added dissonance-inducing activities regarding unhealthy dietary and activity practices, drawing from a highly efficacious dissonance-based eating disorder prevention program. A pilot trial found that this new Project Health intervention significantly reduced increases in BMI relative to both the Healthy Weight intervention and an educational brochure condition from pre to post. The investigators propose to conduct a rigorous multisite effectiveness trial that will test whether adding the dissonance-induction elements to the originally Healthy Weight intervention improves weight gain prevention effects. 360 college students at risk for future weight by virtue of their age and weight concerns will be randomized one of three conditions: (1) a refined 6-hr group-based dissonance-based Project Health, (2) a 6-hr group-based Healthy Weight intervention, or (3) a psychoeducational video ("Weight of the World") condition. Participants will complete assessments of % body fat, mediators (including objectively measured physical activity), moderators, and other outcomes at pre, post, and 6, 12, and 24 month follow-ups.

Aim 1 will test the hypothesis that Project Health significantly reduces increases in % body fat relative to the Healthy Weight intervention and video control condition during a 2-yr follow-up; secondary outcomes are BMI, depressive symptoms and eating disorder symptoms. The investigators will also compare Healthy Weight to video controls. Aim 2 will test the hypothesis that Project Health participants will experience increased cognitive dissonance (an uncomfortable psychological state) regarding eating unhealthy foods and engaging in sedentary behaviors, and that changes in dissonance mediate the program's weight gain prevention effects. The investigators will also test whether reduced calorie intake and increased physical activity mediate the effects of Project Health on change in % body fat. Aim 3 will test the hypothesis that intervention effects are amplified for participants with elevated body dissatisfaction (which should increase motivation change) and preference for consistency (which should maximize dissonance induction) and mitigated for participants who report emotional eating and substance use (because these factors increase risk for overeating).