Resting energy expenditure in professional dancers as an objective measure of low energy expenditure

Objective: To investigate the prevalence of low resting energy expenditure (REE) in ballet dancers and to examine its association with low energy availability (LEA) questionnaires and physiological parameters, including menstrual function and body composition.

Methods: Participants were screened two times during a dance season. Measurements included direct REE (REEm) via gas analysis, body composition, bone health, menstrual status and LEA questionnaires. REEm was compared against eight predictive equations (REEp). Metabolic suppression was defined as an REEm/REEp ratio <0.90.

Results: 47 professional classical ballet dancers (female: n=27, age 24±5.21 years, body mass index (BMI) 18.8±1.67; male: n=20, age 25±4.27 years, BMI 23.1±1.59) volunteered. A high prevalence of suppressed REE was identified, affecting 37.5% of females and 46% of males. No single predictive equation was superior; using multiple equations improved the identification of at-risk dancers. In females, low REE was strongly associated with menstrual irregularity and a significantly later menarche. In males, low REE was linked to lower body fat%. Crucially, low REE was not reliably predicted by low body mass or BMI. Instead, the ratio of kcal/FFM kg/day was a more sensitive discriminator between low and normal REE groups in both sexes. Dancers with low REE also demonstrated less favourable bone health profiles.

Conclusion: Metabolic suppression indicative of LEA is widespread in elite dancers and is not discernible by body mass alone. Clinical screening should incorporate direct metabolic measurement, assessment of menstrual status and evaluation of body composition to effectively identify dancers at risk of the long-term health consequences of relative energy deficiency in dance.