A meta-analysis of the effects of exercise and/or dietary restriction on resting metabolic rate.

A meta-analysis was used to examine the independent and interactive effects of dietary restriction, endurance exercise training and gender on resting metabolic rate (RMR). Sixty different group means (covering approximately 650 subjects) were identified from the scientific literature and subjected to meta-analysis techniques. Collectively (i.e., all groups combined), body weight loss was greater (P < 0.05) for men (approximately 18 kg) than for women (approximately 12 kg). There were no statistically significant exercise training or gender effects on RMR during weight loss. Collectively (i.e., all groups combined), dietary restriction resulted in a -0.59 kJ.min-1 (approximately -12%) decrease in RMR (P < 0.05). When normalized to body weight, RMR was reduced by less than 2% (P < 0.05). These data suggest that exercise training does not differentially affect RMR during diet-induced weight loss. In addition, decreases in resting metabolism appear to be proportional to the loss of the metabolically active tissue.