38 CLINICAL FOCUS
38 CLINICAL FOCUS
22 AUGUST 2025 ausdoc. com. au
Therapy Update
Relative energy deficiency in sport
Sports medicine
The nature and breadth of potential negative impacts of energy imbalance in sports participants has evolved since the female athlete triad was first described in the 1990s.
EXERCISE and sport are important and essential parts of overall health. However, there are times when they can negatively impact the health of individuals.
Relative energy deficiency in sport( REDs) is an example of such adverse effects. The concept was first established in the 1990s with the description of the female athlete triad, whereby energy imbalance was noted to negatively impact menstrual cycles and bone health in female athletes. 1 Since then, the concept has evolved to include athletes irrespective of gender, and broader impacts on physiological function. The International Olympic Committee released the first consensus on REDs in 2014 and updated this most recently in 2023. 2, 3
The 2023 REDs consensus defines REDs as‘ a syndrome of impaired physiological and / or psychological functioning experienced by female and male athletes that is caused by exposure to problematic( prolonged and / or severe) low energy availability( LEA). The detrimental outcomes include, but are not limited to, decreases in energy metabolism, reproductive function, musculoskeletal health, immunity, glycogen synthesis and cardiovascular and haematological health, which can all individually and synergistically lead to impaired wellbeing, increased injury risk and decreased sports performance’. 3
The 2023 consensus update includes a helpful assessment tool( REDs-clinical assessment tool version 2 [ CAT2 ]— see online resources) for practitioners. 6 This also acknowledges gaps in research and evidence, where understanding about diagnosis and management is still evolving.
Scientific conjecture continues between the female athlete triad group, the REDs consensus group and a new group that questions whether it is overreach to consider LEA as being at the core of the issue. 1, 3, 4 Regardless, the demands on athletic populations to balance training load, activities of daily living and physiological function with adequate fuelling, do impact training and competition availability and overall performance during an athlete’ s career. Additionally, these factors can contribute to substantial short-and long-term health deficits.
Presentation
The most common medical presentations associated with REDs are injury( usually bone stress injuries [ BSIs ]), recurrent illness, menstrual dysfunction, poor adaptations to training and poor performance. However, early features can also be elicited with proactive medical screening, using comprehensive processes including relevant questionnaires. 3 REDs is more common in certain cohorts, particularly those
Dr Rachel Harris is a sport and exercise physician in Perth, WA, and project lead for the Australian Institute of Sport Female Performance and Health Initiative, Canberra, ACT.
Dr Ione Patten is a sport and exercise physician registrar in Perth, WA, and was team doctor for the Fremantle Dockers AFLW team and West Coast Fever netball team. Dr Tahnee Bell is a sports and exercise physician registrar in Subiaco, WA, and is team doctor for the Perth Wildcats NBL team.
participating in endurance, aesthetic and weight class sports. In the clinical setting, there is also an increased prevalence in adolescence, those with disordered eating( including restrictive diets), weekend warriors and postpartum women, very often by inadvertent under-fuelling or LEA. It is important also to acknowledge REDs can and does occur in athletes and exercisers of any calibre.
The cornerstone of the diagnosis is based on the impact of inadequate energy supply for the amount of energy that is expended in exercise, activities of daily living and normal physiological function. While short periods of LEA are unlikely to be harmful, prolonged or recurrent episodes can and do cause harm. 3
Diagnosis formulation
REDs is ultimately a diagnosis of exclusion, with no single test ruling it in or out. 3, 4, 6 A thorough history and high index of suspicion is essential, especially when assessing exercising populations, and those with suggestive presentations. The consensus update and REDs CAT2 tool outline a number of questionnaires to identify LEA and disordered eating. These tools, coupled with thorough history( see box 1), all assist the diagnosis. 3, 6
With regards to clinical examination, focus on general observations, including any postural blood pressure or heart rate changes. Abnormal postural tachycardia or hypotension may indicate haemodynamic instability and therefore more severe disease. This warrants urgent referral for tertiary care. An ECG may also be of benefit in this setting. Presentation with bone stress or menstrual cycle changes may be the first presentation of an athlete with a severe eating disorder, mental ill health or orthorexia( obsessive fixation on‘ healthful’ eating).
In a patient presenting with primary amenorrhoea, it is important to correlate Tanner staging and the appropriate development of secondary sexual characteristics, thereby directing investigation.
Primary and secondary indicators have been defined, which have strong or developing evidence for correlation in the diagnosis of REDs( see figures 1 and 2, and box 2). 3, 6
A number of investigations may help establish the diagnosis( see box 2). 3, 6 These include assessment of reproductive hormones, testosterone, and hypothalamic and thyroid function among others. Importantly, not all investigations should be performed, rather the most appropriate ones for the individual. As an example, there is no use performing reproductive hormone profiling for female athletes who are using hormonal contraception, as they will only show exogenous hormones and a disrupted
Box 1. Historical detail to aid diagnosis
• Training load
• Previous history of bone stress injury
• Nutrition and fuelling
• Menstrual cycle history( including current or previous oligomenorrhoea, amenorrhoea and age at menarche)
• Recurrent injury and illness
• Decrease in athletic performance
• Anxiety or depression symptoms
• Reduced libido and morning erections( male athletes)
hypothalamic-pituitary-ovarian( HPO) axis. Functional hypothalamic amenorrhoea can only be confirmed with cessation of hormonal contraception and appropriate washout periods to allow return of HPO feedback, which can take months. For athletes who are not using hormonal contraception, reproductive hormone profiling needs to be repeated at least a fortnight after baseline testing, in order to appropriately assess HPO function. 3, 6
Based on presenting symptoms( eg, BSI), history, examination and blood workup,
Box 2. Clinical criteria / indicators
NEED TO KNOW
Relative energy deficiency in sport( REDs) is a common diagnosis in athletic populations and warrants consideration in the setting of injury or recurrent illness, and poor training and competition performance.
Management should involve the athlete, coach and a multidisciplinary team that includes, but is not limited to, a sport and exercise physician, GP, sports dietitian, psychologist, parents / carers and coaches.
An athlete’ s energy outputs are not limited to training and competition. All facets of life contribute, including work, school, social scenarios, caring / parenting, and puberty / growth.
Treatment of REDs must correct low energy availability and overall load to avoid significant morbidity and unfulfilled athletic potential.
imaging investigations may be required. These may include bone densitometry, pelvic ultrasound or MRI brain to rule out a pituitary lesion. Additional specific testing based on primary symptoms( such as cardiac investigations, gut motility, bladder stress) guide further management.
An additional consideration is that iron deficiency and anaemia are very common findings in this cohort. Iron deficiency is present in 60 % of female athletes, often connected with increased demands, losses( foot-strike haemolysis, sweating, menses), reduced absorption( increased hepcidin and caffeine intake) and poor nutrition literacy and associated behaviours.
Management
Once the diagnosis of REDs has been made, the REDS CAT2 can then be used to identify the severity and help guide management( see figure 3). 6
Severe primary indicators( count as two primary indicators)
• Primary amenorrhoea; or prolonged secondary amenorrhoea( absence of 12 or more consecutive menstrual cycles) due to functional hypothalamic amenorrhoea( FHA)
• Clinically low free or total testosterone( males: below the reference range)
Primary indicators
• Secondary amenorrhoea( females: absence of 3-11 consecutive menstrual cycles) caused by FHA
• Subclinically low total or free testosterone( males: within the lowest 25 % of the reference range)
• Subclinically or clinically low total or free T3( within or below the lowest 25 % of the reference range)
• History of ≥1 high-risk( femoral neck, sacrum, pelvis) or ≥2 low-risk bone stress injury( BSI)( all other BSI locations) within the previous two years or absence of ≥6 months from training due to BSI in the previous two years
• Premenopausal females and males < 50 years old: BMD Z-score < −1 at the lumbar spine, total hip or femoral neck or decrease in BMD Z-score from prior testing
• Children / adolescents: BMD Z-score < −1 at the lumbar spine or total body less head or decrease in BMD Z-score from prior testing( can occur from bone loss or inadequate bone accrual)
• A negative deviation of a paediatric or adolescent athlete’ s previous growth trajectory( height and / or weight)
• An elevated score for the EDE-Q global(> 2.30 in females; > 1.68 in males) and / or clinically diagnosed DSM-5-defined eating disorder( only one primary indicator for either or both outcomes)
Secondary indicators
• Oligomenorrhoea caused by FHA(> 35 days between periods for a maximum of eight periods / year)
• History of one low-risk BSI( see high vs low-risk definition above) within the previous two years and absence of < 6 months from training due to BSI in the previous two years
• Elevated total or LDL cholesterol( above reference range)
• Clinically diagnosed depression and / or anxiety( only one secondary indicator for either or both outcomes)