Self-efficacy or Planning? Effects of a Change in Cognitions on Adolescents’ Behavior and Body fat

Abstract

Background: The study tested the influence of intervention promoting exercise and healthy diet on behaviors and body fat among adolescents. We evaluated the effects of three types of interventions (addressing self-efficacy, planning, and a combination of planning and self-efficacy), compared to changes in a control (education) group. Methods: Data were collected among 1258 adolescents (aged 14-18; 22.1% overweight), who were allocated to four study groups. Behavior, cognitions, body weight, height, and fat tissue were assessed at three measurement points (the baseline, 2-, and 14-month follow-ups). Findings: Significant effects on physical activity were found in the intervention groups which included self-efficacy component. A reduction in body fat at 14-month follow-up was observed in overweight girls participating in self-efficacy or combined (planning + self-efficacy) groups. Among overweight boys, a significant decrease in body fat was found in the combined intervention group. The effects were mediated by changes in self-efficacy and physical activity. Discussion: Self-efficacy was identified as the active ingredient of a healthy lifestyle promotion intervention for adolescents.