EFFECTS OF AEROBIC EXERCISE AND DIETARY CARBOHYDRATE ON ENERGY-EXPENDITURE AND BODY-COMPOSITION DURING WEIGHT-REDUCTION IN OBESE RATE

To test the benefits of aerobic exercise and dietary carbohydrate duri ng reduced-energy feeding, 23 obese women (44 +/- 4% fat) were randoml y assigned to either aerobic exercise (Ex) or no exercise (Nx), and to a low-fat (LF) or low-carbohydrate (LC) reducing diet (5.00 +/- 0.56 MJ/d) for 12 wk. Changes in body composition, postabsorptive resting m etabolic rate (RMR), thermic effect of a meal (TEM), and total daily e nergy expenditure (TDEE) were measured by respiratory gas exchange and doubly labeled water. Significant effects of Ex included a greater lo ss of fat mass (Ex: -8.8 +/- 2.1 vs Nx: -6.1 +/-: 2.3 kg, P = 0.008) a nd maintenance of TDEE (Ex: +0.07 +/- 1.23 vs Nx: -1.46 +/- 1.04 MJ/d, P = 0.004), due to a difference in physical activity (Ex: +0.75 +/- 1 .06 vs Nx: -0.61 +/- 1.03 MJ/d, P = 0.006), which was not attributable solely to the Ex sessions. RMR in both groups decreased comparably (- 0.54 MJ/d), and TEM (% of meal) did not change. Diet composition did n ot significantly influence body composition or energy expenditure chan ges, but a greater weight loss was observed after the LC than after th e LF (-10.6 +/- 2.0 vs -8.1 +/- 3.0 kg, P = 0.037) diet. The addition of aerobic exercise to a low-energy diet was beneficial in the treatme nt of moderate obesity because of its favorable effects on body compos ition, physical activity, and TDEE.