Effects of the interaction of sex and food intake on the relation between energy expenditure and body composition.

BACKGROUND The relation between physical activity energy expenditure (PAEE) and percentage body fat (%BF) is not very strong in the general population. It is possible that variables such as sex, food intake, or both may in part explain this poor coupling. OBJECTIVE This study was designed to show the relation between PAEE and %BF and to determine whether sex, food intake, or both influence the strength of the relation. DESIGN We used doubly labeled water or energy intake balance, indirect calorimetry, dietary interview, and dual-energy X-ray absorptiometry to measure total energy expenditure (TEE), resting energy expenditure (REE), food intake, and %BF, respectively, in 91 healthy persons (women: aged 48 y, 38.6%BF, n = 47; men: aged 47 y, 24.1%BF, n = 44). RESULTS TEE, PAEE, and REE were significantly lower in women than in men. TEE was related to %BF in women (r = 0.53, P < 0.0001) but not in men (r = -0.22, P > 0.05). The relation between PAEE and %BF was significant in men (r = -0.34, P < 0.03) but not in women. PAL was also significantly related to %BF in men (r = -0.36, P < 0.02) but not in women. Macronutrient intake (% of total energy) did not differ significantly between the sexes, but carbohydrate (r = -0.44, P < 0.003) and fat (r = 0.31, P < 0.04) intakes were significantly related to %BF in women. CONCLUSIONS These results suggest that the relation between PAEE and %BF is stronger in men than in women. Macronutrient composition seems have a stronger influence on %BF in women than in men.