Discussion
The present study of 47 professional dancers reveals a high (47%) prevalence of RED-D,1 characterised by a suppressed metabolism that is strongly linked to menstrual dysfunction in females and occurs independently of BMI in both sexes. These data support previous research by Staal et al4 and Doyle-Lucas et al26 who both reported suppressed REE, either compared with predictive equations or against age-matched controls. The cohorts for the three studies were similar in age, height, body mass and BF%, and all participants were recruited from elite national ballet companies. Still, the REEm in the present study was only comparable to Staal et al (females: 1504 kcal/day, males: 1967 kcal/day), with Lucas-Doyle et al ’s data being 150 kcal/day lower (females: 1367 kcal/day). The RER, as an indicator of fuel utilisation, is similar between Doyle-Lucas et al and the current study’s female dancers with normal menses. Still, neither was as high as the irregular menses group. Although not statistically significant, a trend was observed suggesting an inverse relationship between BF% and RER. If confirmed, this could indicate a metabolic strategy to preserve limited fat stores by increasing carbohydrate oxidation, a phenomenon observed in other athlete populations under LEA (table 1). This has implications for fuelling strategies for dancers, which would require more frequent meals to maintain energy levels and prevent fatigue, especially in the later stages of the training day.27
There was widespread metabolic suppression (low REE) across the cohort, with the suggested Staal et al4 90% ratio between REEM/REEP accounting for 37.5% of females and 46% of males. None of the predictive equations was superior using Staal’s ratio, but using multiple equations was beneficial for identifying at-risk dancers, as most exhibited low REE across several calculations. The online supplemental data (10.6084/m9.figshare.30489350) show that, among female dancers, low REE status was not a fixed characteristic, with 80% of dancers classified as low REE also having at least one test with a normal REE ratio. Sixty-three per cent of this cohort also had irregular menses and menarche at 15+ years old, 3 years later than the normal REE group, which is a strong indicator of long-term energy deficiency.28 Golden and Carlson29 reported that it was LEA rather than exercise load that suppresses the gonadotrophin-releasing hormone and values below 30 kcal/FFM kg/day were associated with low LH and FSH. This clinical indicator of LEA in females30 was observed in both male and female cohorts, with kcal/FFM kg/day being more sensitive than kcal/BW kg/day in differentiating between the REE groups. This potentially highlights the importance of monitoring FMM and body fat% with this population, which is often considered to be controversial due to pressures on body thinness and eating disorders.31
Our findings reveal a paradoxical relationship between REE and body composition in dancers, as determined by REEm/REEp ratios below 90%. Contrary to expectations, male dancers categorised as having low REE exhibited slightly higher FFM but lower BMI compared with those with normal REE. This finding aligns with research by Trexler et al,32 who reported that metabolic adaptation to energy deficiency can occur independently of changes in body mass or composition. In the male low-REE cohort, the group had a lower body fat percentage, and we propose that REE is suppressed to protect the remaining body fat in case energy availability declines.
In female dancers, those categorised as having low REE showed slightly higher FFM and BMI, which contrasts with typical expectations. Also, the body fat percentage is similar between the low and normal REE groups. Still, the group with irregular menses, accounting for 63% of the low-REE group, had a lower body fat percentage. Detrimental bone health is the result of long-term REDs,33 and the current low-REE cohort was beginning to manifest the effects of LEA on bone health, as demonstrated by lower, but not significant, BMD and z-scores in both male and female cohorts. This paradox may be explained by the concept of ‘adaptive thermogenesis’ described by Müller and Bosy-Westphal,34 where the body reduces energy expenditure beyond what would be predicted by changes in body composition alone.
The relationship between self-reported symptoms and objective markers of LEA in this cohort was complex and sex-specific. The LEAF-Q successfully identified female dancers with two key historical markers of long-term energy deficiency (later menarche and lower body fat percentage).28 31 Yet, it failed to differentiate based on current metabolic suppression (REEm/REEp ratio) or bone health. This disconnect suggests that in elite dance populations, where body image pressures and symptom normalisation are high,31 questionnaires may be prone to under-reporting or may capture different aspects of the REDs spectrum than a physiological measure like REE. Specifically, the LEAF-Q may be more sensitive to chronic, historical LEA rather than acute metabolic adaptations. Alternatively, the non-specific nature of some questionnaire items may limit their usefulness, as gastrointestinal issues and injuries are prevalent among dancers regardless of energy status. In contrast, the LEAM-Q showed no significant associations with any physiological or metabolic variable in male dancers. This finding aligns with the developers’ own work,19 which noted challenges in questionnaire validation and suggested that specific symptom questions (eg, low libido) may be more effective indicators than a composite score. The very low number of male dancers classified as ‘at risk’ by the LEAM-Q (n=4) in our study also limits statistical power and underscores the ongoing difficulty in developing practical, self-report screening tools for LEA in males. Therefore, while questionnaires remain a useful first-step screening tool for raising awareness, they should not be considered a substitute for direct metabolic measurement when available. Further research is needed to determine the predictive validity of these tools relative to objective markers such as REE in elite dancer populations.
Clinical implications
The findings of this study have several practical implications for clinicians and practitioners working with elite dancers. Direct measurement of REE, combined with the REEm/REEp ratio using multiple predictive equations, provides a valuable non-invasive indicator of LEA. The use of a battery of predictive equations (rather than reliance on a single equation) significantly improves sensitivity for identifying dancers with metabolic suppression, as no single equation proved superior in this cohort. Clinicians should therefore calculate REEm/REEp ratios using at least 4–5 established equations and classify dancers as ‘at risk’ if they fall below 0.90 on two or more equations. The REEm data and graphical output from metabolic testing offer an educational opportunity to discuss energy demands with dancers. Presenting the calculated energy deficit can help dancers understand the gap between their current energy intake and their physiological requirements. This objective feedback may be more impactful than dietary advice alone, particularly in populations where body image pressures can hinder open discussion of eating behaviours.
Clinicians should be aware that the markers associated with low REE differ by sex. In female dancers, menstrual status is a critical indicator. Those with irregular menses or later menarche (≥15 years) should be prioritised for REE screening, as they are significantly more likely to exhibit metabolic suppression. In male dancers, very low body fat percentage (<6%) emerged as a key risk factor, even in the absence of low BMI. Body composition assessment should therefore be an integral part of routine screening for male dancers. The finding that kcal/day FFM/kg was a more sensitive discriminator between low and normal REE groups than kcal/day BW/kg underscores the importance of regular body composition monitoring. FMM should be used as the denominator when calculating relative energy expenditure, and practitioners should advocate for including bioelectrical impedance analysis or similar methods in routine health screening, despite sensitivities around body composition testing in dance populations.
While dancers in this study reported that the REE test was neither invasive nor tiring, the overnight fasting requirement poses logistical challenges given their demanding schedules. To facilitate compliance, practitioners should schedule testing early in the morning, before training commences; provide on-site facilities (fridge, microwave, kettle) to allow dancers to eat immediately after testing; and offer clear written instructions and explain the rationale for fasting to improve adherence.
The trend towards lower BMD and Z-scores in dancers with low REE, while not statistically significant in this cohort, reinforces the need for proactive bone health monitoring. Dancers identified as having suppressed REE should be prioritised for DXA scanning and considered for early nutritional intervention to mitigate long-term consequences, including stress fracture risk and osteoporosis.
Limitations
The participant group comprised only one professional ballet company in the UK, and therefore, numbers were limited but similar to those in previous published research on dance.4 26 Even though 16 Global Majority dancers were in the company, only five volunteered for the study, which was not enough to form a subcategory. Purposeful recruitment of this population would allow better insight into whether different equations and/or categorisation are needed, or whether the selection/audition process for entry into a ballet company makes this moot. Further information on eating disorders/disordered eating from questionnaires19 20 was not collected, which would have provided a further dimension to the study.
