ENERGY-EXPENDITURE UNDER FREE-LIVING CONDITIONS IN NORMAL-WEIGHT AND OVERWEIGHT WOMEN

Total energy expenditure under free-living conditions of 12 normal-weight and 26 overweight women was determined with the (H2O)-H-2-O-18 method. Overweight women tended to expend more energy (xBAR +/- SD, 11.20 +/- 1.79 MJ/d) than normal-weight women (9.46 +/- 0.87 MJ/d, P < 0.005). Approximately half of this effect was explained by an increase in basal metabolic rate (BMR) in the overweight group compared with the normal-weight group (6.47 +/- 0.74 vs 5.68 +/- 0.39 MJ/d, respectively, P < 0.005) and the other half by an increase in above-basal energy expenditure (4.73 +/- 1.49 vs 3.78 +/- 0.94 MJ/d, P < 0.05). Total energy expenditure was approximately 1.7 times the BMR in both groups. After adjusting energy expenditure for weight or lean body mass by analysis of covariance, there was no significant difference between normal-weight and overweight groups. We conclude that most overweight subjects must consume more energy than lean subjects to maintain their excess weight, although some could maintain their obesity without eating more than lean subjects.