The effects of exercise, training on body composition and metabolism in men and women.

In order to examine whether there are sex-differences in the response of energy balance to physical training slightly obese men and women participated in the same 3 months physical training program with the same individual relative intensity. The men became somewhat lighter (-2 kg) and leaner (-2.9 kg body fat) and showed decreases in sum of insulin and sum of C-peptide values during an oral glucose tolerance test as well as cholesterol values. The women showed decrease of 2.6 kg body fat, and also increased lean body mass (1.9 kg) and similar metabolic changes. The women had, however, a larger body fat mass at the outset. When women with similar body fat mass as that of men were analysed separately, no change in body weight or body fat had occurred, and the metabolic adaptations were less pronounced. No compensatory increase of energy intake could be discovered in any of the groups, the most obese women actually showed a decrease. Taken together with previous information these results suggest that men, like male rats, become leaner during physical training due to a lack of energy intake compensation. Women with similar body fat mass, however, like female rats, may react with such a compensation, causing a protection of their body fat. Women usually have more body fat than men, however. Obese women in this study showed a decrease of body fat.