Exercise-induced weight loss preferentially reduces abdominal fat

Purpose: To investigate whether abdominal fat is reduced in response to substantial weight loss induced by exercise in young obese men. Methods: Thirty obese men (mean age 19.8 +/- 0.6 yr) were evaluated before (pretraining) and after (posuraining) 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 posuraining responses were analyzed with a paired t-test. Results: Subjects lost 12.0 +/- 3.6 kg (P < 0.001) from pre- to posuraining, 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. Conclusions: 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.