The purpose of this study was to determine whether body composition alterations induced by aerobic exercise training show seasonal varition. Ninety-five middle-aged Japanese obese women volunteered as subjects. All subjects participated in our “exercise+diet” program for 3 months. The subjects were categorized into two groups (Summer group : S, and Winter group : W) based on the season when they participated in the program. Body composition, cardiorespiratory variables and dietary habituation were evaluated before and after the programs. More desirable changes in body composition were observed in Group W than in Group S. Group W showed a significant decrease in body mass from 62.2±8.7 kg to 60.3±8.6 kg, and in percentage body fat from 34.0±7.0% to 30.5±6.0%, while fat-free mass increased significantly from 41.0±3.9 kg 41.9±3.6 kg. However, alterations in cardiorespiratory variables were not associated with body composition alterations. It is concluded that season may have an effect on body composition alterations, but has no effect on cardiorespiratory variables, and that body composition may be improved by an exercise+diet program more effectively in winter than in summer.

Exercise-induced changes in body composition are dependent on various external factors. The psychological factor seems to be an important determinant for reducing body mass. However, the effect of changes in mood on weight loss have not been thoroughly investigated. The purpose of this study was to investigate the relationships among mood status, body composition and anthropometric characteristics observed during an exercise training program. Thirty-four obese women, aged 46.5±7.7 years, participated in our 3-month weight loss program. Body mass and % fat significantly decreased from 66.3±7.1 kg to 59.8±6.5kg, and from 31.8±3.1% to 27.9±4.0% (P<0.05), respectively. Aerobic power, as represented by maximal oxygen uptake, significantly increased (from 29.1±5.0 mlin/kg to 34.6±5.2 mlin/kg), and oxygen uptake corresponding to lactate threshold increased as well (from 17.2±2.8mlin/kg to 20.0±3.0mlin/kg) after training (P<0.05) . Accord. ing to the degree of body mass change, the subjects were divided into the following two groups : good-responder group (Group G : -9.2±2.7 kg) and poor-responder group (Group P : -3.8±1.4 kg) . Analyses of variance revealed significant differences (P<0.05) in total mood disturbance between Group G (103.54±16.30) and Group P (115.20±21.17) . These results show the possibility of the effects of mood on the success of weight loss in obese middle-aged women.