Physical Exercise in Obesity and Anorexia Nervosa

Abstract

A more sedentary lifestyle and reduced energy expenditure are frequently proposed as causes of the obesity pandemics in westernized societies. This hypothesis is sound for a number of reasons, as recently reviewed by Popkin [1]. Briefly, rapid changes in physical activity patterns are occurring worldwide due to: (1) occupational changes from agriculture and labor-intensive jobs towards the tertiary sector of the economy; (2) a reduction of the level of physical activity within each occupation; (3) changes in transportation systems, substantially reducing the need for walking; (4) changes in education and in leisure activity patterns; and (5) the introduction of labor- saving domestic devices and of more convenient food sources and locations, decreasing the cost of all home production-related activities. These changes in physical activity are characteristic of the transition from a developing to an industrialized society and are associated with a higher mean body mass index (BMI) and a greater prevalence of obesity among people in those countries. Therefore, it seems natural to assume that energy expenditure differs between populations at different stages of their social and economic development and that these differences explain, at least in part, different rates of obesity.