Impact of regional and total body composition and hormones on resting energy expenditure in overweight postmenopausal women.

The independent impact of regional and total body composition and sex and thyroid hormone levels on resting energy expenditure (REE) was assessed in 121 healthy, overweight (body mass index [BMI], 25 to 42 kg/m2), postmenopausal women (aged 49 to 58 years). REE was measured by indirect calorimetry with a ventilated hood, and the total, trunk, and peripheral body composition by dual-energy x-ray absorptiometry (DXA). Sex and thyroid hormone levels were also measured. REE correlated significantly (P < .05) better with trunk lean tissue mass ([LTM] r = .61) than with total-body (r = .53) or peripheral LTM (r = .30). Trunk LTM (R2 = .37), total-body fat tissue mass ([FTM] R2 = .04), androstenedione (R2 = .03), and total triiodothyronine ([T3] R2 = .02) were all significantly independently associated with REE. Together they explained 46% (model R2) of the interindividual variation in REE, with a standard error of estimate (SEE) of 549 kJ/d. We conclude that the interindividual variation in REE is explained mainly by differences in the visceral component of LTM, with additional minor information from the total-body FTM, androstenedione, and T3.