Physical activity in the prevention of obesity: current evidence and research issues.

PURPOSE: The relation between habitual physical activity and the prevention of overweight and obesity in adults based on the evidence from the epidemiologic literature is described.
METHODS: Literature was reviewed of current findings from large population-based studies of forward directionality in which physical activity was considered as a primary study factor.
RESULTS: The longitudinal evidence suggests that habitual physical activity plays more of a role in attenuating age-related weight gain, rather than in promoting weight loss. Moreover, recent data suggest that increasing amounts of physical activity may be necessary to effectively maintain a constant body weight with increasing age.
CONCLUSION: Over decades, small savings in excess weight gain accumulate into net savings that may be quite meaningful with regard to minimizing the risk associated with obesity-related disorders. The question remains as to how important maintaining a constant body weight through middle age and into older age is to healthy, already-active people of normal body weight.