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.