Postabsorptive resting metabolic rate and thermic effect of food in relation to body composition and adipose tissue distribution.

One hundred thirty subjects were studied to investigate relationships between the body composition and fat distribution as evaluated by computed tomography and the resting metabolic rate (RMR) as evaluated by indirect calorimetry: 82 premenopausal women (age, 18 to 52 years; body mass index [BMI], 27 to 52 kg/m2), 27 postmenopausal women (46 to 71 years; 28 to 49 kg/m2), and 21 men (18 to 70 years; 31 to 43 kg/m2). The thermic effect of food (TEF) was evaluated in all men and in 2 subgroups of 55 and 19 women. The best-fitting equations for predicting RMR, obtained by multiple regression, included the following as covariates: fat-free mass and both subcutaneous and visceral adipose tissue in premenopausal women (R2 = .55, P = .0001), fat-free mass and visceral adipose tissue in postmenopausal women (R2 = .58, P = .001), and age, with minus sign, and visceral adipose tissue in men (R2 = .44, P = .0051). Fasting insulin and fat-free mass, with minus sign, and both visceral and subcutaneous adipose tissue were the predictors of the TEF (R2 = .25, P = .0055) in premenopausal women. This study demonstrates that visceral fat distribution is important in determining the RMR in postmenopausal women and men. In premenopausal women, total adipose tissue is a main determinant of both the RMR and TEF This last effect could be counterbalanced by insulin resistance.