Decreased resting metabolic rate in ballet dancers with menstrual irregularity

We studied 21 ballet dancers aged 19.4 +/- 1.4 years, hypothesizing that un dernutrition was a major factor in menstrual irregularity in this populatio n. Menstrual history was determined by questionnaire. Eight dancers had alw ays been regular (R). Thirteen subjects had a history of menstrual irregula rity (HI). Of these, 2 were currently regularly menstruating, 3 had short c ycles, 6 were oligomenorrheic, and 2 were amenorrheic. Subjects completed a weighed dietary record and an Eating Attitudes Test (EAT). The following p hysiological parameters were measured: body composition by anthropometry, r esting metabolic rate (RMR) by open-circuit indirect calorimetry, and serum thyroid hormone concentrations by radioimmunoassay. R subjects had signifi cantly higher RMR than HI subjects. Also, HI subjects had lower RMR than pr edicted by fat-free mass, compared to the R subjects. Neither reported ener gy intake nor serum thyroid hormone concentrations were different between R and HI subjects. EAT scores varied and were not different between groups. We concluded that in ballet dancers, low RMR is more strongly associated wi th menstrual irregularity than is current reported energy intake or serum t hyroid hormone concentrations.