Background: Despite careful planning and implementation, overweight/obesity prevention interventions in children and adolescents typically show no, inconsistent or merely weak effects. Such programs usually aim at behavior changes, rarely also at environmental changes, that draw upon conventional wisdom regarding the commonly accepted determinants of childhood overweight/obesity.
Objective: This paper evaluates the evidence base of the apparently overweight-/obesity-related determinants diet, physical activity and stress. The results of international intervention studies are discussed against this background.
Methods and materials: Based on the mediating-moderating variable model, we investigate the effect of theory specified mediating variables and how potential moderating variables may impact these relationships.
Results: Contrary to common beliefs, recent research has revealed inconsistent evidence regarding associations between potentially obesogenic behaviors and overweight/obesity in youth. Moreover, the evidence for strong and causal relationships between mediating variables and targeted behaviors seems to be inconsistent. In addition, inadequate attention is paid to moderating effects.
Discussion: The etiology of overweight/obesity in youth is likely the result of a complex interplay of multi-causal influences. Future prevention interventions would benefit from a more thorough understanding of the complex relationships that have been hypothesized and of the mechanisms of suspected behaviors for affecting overweight/obesity. Only if substantial change can be demonstrated in mediators with reasonable effort under real world circumstances, it will make sense to progress to community behavior change trials.
Keywords: Behavioral prevention; Mechanisms of action; Mediators; Moderating variables; Structural prevention.