Exercise-induced weight loss preferentially reduces abdominal fat.

Abstract

To investigate whether abdominal fat is reduced in response to substantial weight loss induced by exercise in young obese men. Thirty obese men (mean age 19.8 +/- 0.6 yr) were evaluated before (pretraining) and after (posttraining) 4 months of regimented training in the Singapore Armed Forces. There were 30 obese male subjects (mean age 19.2 +/- 1.3 yr) without training who were monitored as control subjects. Fat free mass (FFM), fat mass, and percent body fat were determined from skinfold measurements. Differences between pre- and posttraining responses were analyzed with a paired -test. Subjects lost 12.0 +/- 3.6 kg (P < 0.001) from pre- to posttraining, which was attributable to a reduction in fat mass (P < 0.001), as FFM was unchanged. Both waist circumference (WC) and hip circumference (HC) decreased (P < 0.01), the reduction in WC (13.7%) being greater than the reduction in HC (7.7%) as reflected by the decrease in waist-to-hip ratio (WHR; P < 0.001). These data reveal that large exercise-induced weight losses are associated with maintenance of FFM. The significant reduction in WHR indicates a greater mobilization of abdominal fat and a preferential loss of fat from this region. Large exercise-induced weight loss is associated with a preferential reduction in abdominal fat and a corresponding maintenance of FFM. Such an effect on body composition should reduce disease risk and the eventual weight regain that typically follows diet-induced weight losses with obese subjects.