Energy Conservation in Amenorrheic Ballet Dancers

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 ± 1.1 kcal/kg/day for amennorheic dancers vs. 25.0 ± 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.