During the past three decades the prevalence of child and adolescent obesity has tripled and currently 31.7% of children and adolescents are either overweight or obese. This is of concern due to the reported metabolic, psychological and social consequences associated with excess weight gain. While obesity occurs as the result of a sustained energy imbalance, there are many reported factors associated with its etiology. Interventions that can favorably impact such factors such as a healthy diet and physical activity could help prevent its onset early in life and spare children from reported metabolic and psychological consequences. Schools are one place intervention strategies are needed, however many obesity prevention interventions that have been implemented in this setting have produced mixed or modest outcomes. The after-school time frame is another excellent opportunity for such strategies, however less work has been done in this area compared with school-based interventions and more studies are needed. The purpose of this study was to evaluate the efficacy of a social cognitive theory based childhood obesity intervention with children in the after-school environment.

This study employed a group randomized controlled design, whereby a convenience sample of twelve after-school programs were randomized into either an experimental (social cognitive theory based) or comparison (knowledge-based) intervention. A pretest, post-test and three month follow up test was conducted to evaluate the programs effects on BMI-percentile, key obesity prevention behaviors (fruit & vegetable consumption, sugar-sweetened beverage consumption, sugar-free drink & water consumption, the engagement of physical activities, and the engagement of sedentary activities), and three constructs of social cognitive theory (self-efficacy, expectations (comprising of outcome expectations and outcome expectancies), and self-control) related to each behavior. Both interventions consisted of four-30 minute sessions that were implemented over a four-week period. Process evaluations were used during each session to evaluate program fidelity and dose.

A convenience sample of 71 children (37 in the experimental and 34 in the comparison) completed the interventions and were used for the final data analyses in this study. Results indicated that study variables and demographic variables were not different for children in the assigned groups at baseline. Process evaluations suggested that both programs were implemented as planned. It was found that BMI-percentile, all obesity related behaviors, and social cognitive theory constructs did not change between groups over the course of the intervention. There was however a significant main effect, indicating an improvement in both groups for fruit and vegetable consumption, the engagement in physical activity, the engagement in screen time, water and sugar free beverage consumption and self efficacy for fruit and vegetable consumption and physical activity. It can be concluded that the two interventions in this study may not have been very different from each other to discern changes. It is also likely that the experimental intervention may not have been of adequate length to truly produce the desired changes targeted in this study. More work is needed in this area to find appropriate, theory-based, health education programs that can complement larger health promotion efforts.