[Physical activity and obesity].

One reason for the high prevalence of overweight and obesity might be the differences in lifestyle compared to earlier decades, called the "obesogenic environment." With this, the decline in physical activity (PA) in favor of a sedentary lifestyle is assumed to play an important role. Physical activity or inactivity has a major impact on the development of overweight and obesity as well as on certain metabolic disorders. This review summarizes current scientific knowledge regarding the association between PA and overweight/obesity. The term "physical activity" is defined and different methods of its assessment are introduced. In addition, certain methods for the evaluation/operationalization of collected PA data are described. Finally, some epidemiological studies dealing with the associations between PA and overweight/obesity in children/adolescents as well as in adults are presented.