Psychological Mechanisms of Interactions between Improvements in Exercise and Healthy Eating Behaviors (Coaction) within a Community-Based Obesity Treatment Setting.

Coaction refers to positive change in one behavior increasing the probability of positive change in a second behavior. Because mechanisms of coaction have not been well studied, and its improved comprehension might optimize architectures of multi-component behavioral obesity interventions, this research aimed to incorporate theory to assess whether treatment-associated changes in self-regulation and self-efficacy sequentially mediate an association between increased exercise and improved eating. Women with obesity ( age = 47.9 years) were randomized into community-based obesity treatments with either a self-regulatory skills emphasis ( = 47), or a more equal focus on education and self-management ( = 52). Each treatment aimed to foster weight loss and reductions in health risks. Over 6 months, there were significant improvements in exercise outputs, fruit/vegetable consumption, sweets intake, exercise- and eating-related self-regulation, and exercise- and eating-related self-efficacy that were significantly greater in the high self-regulation group. Using aggregated data, bivariate relationships between changes in exercise, and fruit/vegetable and sweets intake, were significant. Serial mediation analyses indicated that increased exercise outputs were associated with improved eating through the sequential relationships of eating-related self-regulation and self-efficacy, while improved eating was associated with increased exercise more directly through exercise-related self-regulation. Moderation analyses demonstrated stronger associations in the high self-regulation group for relationships between changes in exercise and eating-related self-regulation and self-efficacy only. Results initiated analyses into mechanisms of coaction among exercise and eating behaviors, and reinforced the value of self-regulatory skills enhancement directly and through its effects on domain-specific self-efficacy in behavioral obesity treatments.