Women, nutrition and exercise: a review of athletes' intakes and a discussion of energy balance in active women

Given the heightened interest in nutritional aspects of exercise, and an increase in athletic participation by women, it appeared timely to review the nutritional implications of exercise in women. The initial part of this paper contains a compilation of published studies on the nutrient intakes of female athletes. These reveal that most groups of athletes have adequate nutrient intakes, and that their vitamin and mineral intakes appear to be superior to those of nonathletic women. The average energy intake of athletes in studies summarized in this paper was 2069 kcal, and for certain groups of athletes, energy intakes were even lower. How these women manage to train intensely while consuming energy intakes similar to those of sedentary women is not readily apparent, and for this reason, the remainder of the paper discusses energy balance as affected by activity. Methodological considerations related to assessment of the components of the energy balance equation (food intake, energy expenditure, and body energy stores) are presented, with a focus on considerations in women. The effects of activity on each of these components are then discussed in an attempt to determine whether some form of energy conservation may occur. Finally, effects of activity on the menstrual cycle are reviewed. The observed changes are discussed in relation to nutrition 1) in terms of how nutrition may play a role in their causation; and 2) in terms of their nutritional implications for the amenorrheic athlete, specifically as regards energy balance and bone density.