Energy expenditure and body composition - Body Composition

Nutrition Research Newsletter, March, 2004

Despite the widely held notion that maintaining or reducing body weight or fat is facilitated by an increase in physical activity, the relation between physical activity energy expenditure (PAEE) and body composition is not very strong. These results suggest that the maintenance of a healthy body weight or body composition, or both, may not be related to PAEE alone and that other variables related to energy balance (such as the regulation of food intake) may be equally important. An additional variable that may alter the strength of this relation is sex. Few studies show the apparent sex difference in the relation between energy expenditure (EE) and body composition, and none report food intake data. Therefore, the purposes of the present study were to investigate the relation between EE and body composition in women and in men and to examine the importance of food intake to this relation.

Ninety-one healthy adult volunteers (47 women and 44 men) participated in the study. Resting EE (REE) was measured with the use of respiratory gas analysis using a ventilated hood for 40 min in the early morning after a 12-hr overnight fast. Total energy expenditure (TEE) was measured by using the doubly labeled water method (27 women and 12 men) or the energy intake (EI) balance method (20 women and 32 men). EI and the macronutrient composition were determined by 24-hr recall.

TEE, REE, and PAEE were significantly greater for men than for women, but physical activity level (PAL) did not differ significantly between the sexes. Dietary recalls indicated that energy and macronutrient intakes were greater in men than in women. There was a significant relationship between percent body fat and macronutrient intake in women. The results of the present investigation confirm those of previous studies indicating that the relation between PAEE and ¿ is not very strong, and is significant in men but not in women. According to the results of the dietary recalls, fat and carbohydrate intakes may explain part of this sex difference. The relation between PAEE and ¿ indicates that active subjects were not more likely to have a lower ¿ than were sedentary subjects. It is possible that sex-specific differences in metabolism may explain the lack of a significant relation between PAEE and ¿ and the role that food intake plays in that relation.

In conclusion, the relation between PAEE and ¿ is negative and statistically significant only in men. The macronutrient composition seems to have a higher influence on ¿ in women than in men. A possible explanation for the lack of such a relation in women may be the carbohydrate and fat intakes in their diet. Future research must focus on more accurate methods of tracking food intake and must investigate means to reduce the potential for body fat accumulation in women.

D. Paul, J. Novotny, W. Rumpler. Effects of the interaction of sex and food intake on the relation between energy expenditure and body composition. Am J Clin Nutr 79:385-389 (February 2004) [Correspondence: J. A. Novotny, USDA, DHPL, 308 Center Drive, Beltsville, MD 20705. E-mail: novotny@bhnrc.arsusda.gov]