Weight-Loss Treatment-induced Physical Activity Associated with Improved Nutrition through Changes in Social Cognitive Theory Variables in Women with Obesity

Abstract

Behavioral weight-loss treatments have typically been unsuccessful and a theoretical. Even when treatments were scientifically derived, theory has rarely been used to decompose, and understand the bases of, their effects. This 2-year study evaluated mediation of the prediction of nutritional changes by changes in physical activity, through social cognitive theory variables. Data from women with Class 1-2 obesity, classified as "insufficiently active" (N = 50; Mage = 47.6 years), were extracted from 2 initial trials of a new cognitivebehavioral intervention. That treatment sought to improve self-regulation, mood, and self-efficacy through increased physical activity, to then induce improved eating and long-term weight loss. Data showed significant improvements in self-regulation for controlled eating, mood, self-efficacy for eating, physical activity/exercise outputs, and intake of fruits/vegetables and sweets. In the prediction of changes in fruit/vegetable intake over 6, 12, and 24 months by physical activity changes, changes in the 3 psychosocial variables were significant mediators. For each of those significant overall models (R 2 -values =.31, .30, and .25, respectively), selfregulation and self-efficacy change were independent mediators. When change in sweets was substituted for fruits/vegetable intake in otherwise identical models, although overall significance was not found, change in mood was a significant mediator. Changes in intake of fruits/vegetables and sweets significantly predicted a 2-year mean weight loss of 5.4 kg (-5.7% reduction). Results generally supported the basis for the architecture of the new cognitive-behavioral treatment. Based on findings, much of the effect of physical activity/exercise on weight loss could be explained through its impact on psychosocial correlates of healthier eating. AbstractBehavioral weight-loss treatments have typically been unsuccessful and atheoretical. Even when treatments were scientifically derived, theory has rarely been used to decompose, and understand the bases of, their effects. This 2-year study evaluated mediation of the prediction of nutritional changes by changes in physical activity, through social cognitive theory variables. Data from women with Class 1-2 obesity, classified as "insufficiently active" (N = 50; Mage = 47.6 years), were extracted from 2 initial trials of a new cognitive-behavioral intervention. That treatment sought to improve self-regulation, mood, and self-efficacy through increased physical activity, to then induce improved eating and long-term weight loss. Data showed significant improvements in self-regulation for controlled eating, mood, self-efficacy for eating, physical activity/exercise outputs, and intake of fruits/vegetables and sweets. In the prediction of changes in fruit/vegetable intake over 6, 12, and 24 months by physical activity changes, changes in the 3 psychosocial variables were significant mediators. For each of those significant overall models (R 2 -values = .31, .30, and .25, respectively), self...