Exercise is an important part of weight management, particularly in the long term. However, there is conflicting evidence about how much exercise obese subjects need to perform. Diet, genetic or other factors may contribute to the difference in weight between normal and obese subjects if physical activities are equal between groups. Obese subjects may therefore need to be more active and perform more exercise than their normal weight counterparts in order to lower or maintain their weight.
Regarding the amount of exercise, duration has a greater effect on weight loss than intensity. Moderate-intensity exercise is as beneficial as high-intensity exercise for weight loss and, as it appears to be more attractive to obese subjects, leads to a greater adherence to exercise programmes.
Preservation of lean body mass is greater when exercise is performed as part of a weight management programme. If diet only is used for weight loss, lean tissue is lost. Combining aerobic and resistance exercise appears to preserve lean tissue, so both types of exercise should be encouraged. Aerobic exercise has a greater effect on weight loss, but resistance exercise could potentially increase lean tissue. High-intensity exercise may spare more lean tissue than moderate exercise, but the benefits of greater adherence of subjects to moderate exercise outweigh those of high-intensity exercise.
When barriers to exercise exist, lifestyle changes combined with diet should be advised. In general, obese subjects should be encouraged to start off with low-intensity exercise and gradually progress to a higher level.
