Abstract--Ballet dancers may be at risk of eating disorders, and women with eating disorders are at increased risk for menstrual dysfunction. Caloric intakes of amenorrheic dancers have been reported to be less than those of eumenorrheic dancers, indicating a possible conservation of energy. We evaluated resting metabolic rate and the thermic effect of food following ingestion of a 500-kcal liquid supplement in 8 amenorrheic dancers and 10 eumenorrheic dancers. Body fat was higher for the eumenorrheic group (20%) than the amenorrheic group (15%). Resting metabolic rate did not differ between groups when corrected for body mass (24.2 [+ or -] 1.1 kcal/kg/day for amennorheic dancers vs. 25.0 [+ or -] 0.9 kcal/kg/day for eumennorheic dancers), nor did resting metabolic rate differ when adjusted for lean mass. However, amennorheic dancers expended significantly less energy post-prandially once adjusted for lean mass (ANOVA, effect of group p = 0.035). Dancers were asked to complete the Eating Disorder Inventory, a self-report scale that measures symptoms of disordered eating; 9 of 10 eumennorheic but only 4 of 8 amennorheic women were willing to complete the questionnaire. Eumennorheic dancers had profiles similar to or less pathologic than those of non-eating-disordered populations. Greater dissatisfaction was expressed by eumennorheic women as body fat increased. Contrary to the findings in previous studies, amennorheic ballet dancers did not exhibit energy conservation via reductions in resting metabolic rate but did expend slightly less energy in thermic effect of food compared to normally menstruating women. Med Probl Perform Art 2006;21:97-104.
Women athletes who participate in sports demanding extreme thinness, such as dancing and distance running, often exhibit disorders of the reproductive system. (1-3) Several factors have been proposed to contribute to this reproductive pathology. The intensity or duration of the training regimen, restrictive eating practices, low body weight, and low percent body fat have all been suggested to contribute to these disorders. However, it is becoming increasingly apparent that a strong association exists between restrictive eating practices and menstrual dysfunction. (4)
Low energy availability has been demonstrated to disrupt luteininzing hormone pulsatility in exercising women. (4) Caloric intakes of amenorrheic women athletes have been found to be less than those of their eumenorrheic counterparts, (2) despite similar or even greater activity levels. The groups of athletes would not be expected to differ from one another given that all groups were weight stable. Thus, there is a discrepancy between predicted expenditure and estimated intake.
Several factors might explain such a discrepancy: either food intake must be underestimated or caloric expenditure overestimated. Lower resting metabolic rates or a decreased thermic effect of food would contribute to an error in predicted energy expenditure. The literature is conflicting in this regard. Myerson at al. (5) and Myburgh et al. (6) found reductions in resting metabolic rate per kilogram of fat-free mass in amenorrheic women (5) or in those with a history of menstrual dysfunction, (6) as compared to both eumenorrheic athletes and controls. However, Wilmore et al. (7) found no reduction in metabolic rate in amenorrheic...