A review of low energy availability in team sport found prevalence between 0% and 80%

Relative energy deficiency in sport — REDs — describes what happens when an athlete's energy intake does not cover the cost of training and the cost of staying alive. The syndrome was named by an International Olympic Committee expert panel in 2014 and has been through two consensus revisions since [s2]. Most of the evidence behind it comes from endurance and aesthetic sports, where the incentive to be light is explicit.

A systematic review published on 22 October asked what is actually known in team ball sports, where that incentive is weaker and the training load is intermittent [s1]. The answer is: not much, and what exists does not agree with itself.

What the review found

Six databases were searched in October 2024 for original English-language articles published from 2005 onwards that measured the prevalence of REDs, low energy availability (LEA), or the female athlete Triad in elite team ball sport athletes aged 18 or older [s1].

Fourteen studies met the criteria — two case studies, two longitudinal, ten cross-sectional — covering 265 athletes across 12 team ball sports [s1].

Two hundred and sixty-five athletes. For a syndrome that has its own IOC consensus statement, a clinical assessment tool and training recommendations attached to it [s2], the elite team-sport evidence base is roughly the size of a large single-club squad list.

Why the prevalence range is meaningless as stated

The twelve cross-sectional and longitudinal studies used six different methods to identify REDs or LEA, and reported prevalence anywhere from 0% to 80% [s1].

The review's contribution is to break that range down by method rather than presenting it as a finding:

• Seven studies used energy availability calculations and identified clinical LEA — below 30 kcal per kg of fat-free mass per day — in 26.3% to 63.6% of athletes [s1].
• The Low Energy Availability in Females Questionnaire identified LEA in 29.6% to 80.0% of participants across four studies [s1].
• Two studies evaluated REDs via blood or salivary markers, finding low total testosterone in 0% to 36.4% of participants [s1]. One study found 50% with low free testosterone, 9.1% with low free T3, and 13.6% with elevated LDL cholesterol [s1].
• The REDs Specific Screening Tool classified 33.3% of athletes as at medium risk in one study [s1].
• One study distributed the Exercise Dependence Scale and the Eating Disorder Examination Questionnaire together, finding prevalence of 4.3% and 25.5% respectively [s1].

These are not measurements of the same thing. An energy availability calculation is an arithmetic estimate built from a food diary and an estimate of exercise energy expenditure, both of which carry substantial error. A questionnaire captures self-reported symptoms. A hormone panel captures a downstream physiological state that has many causes besides underfuelling. Reporting them under one prevalence figure implies a comparability that does not exist.

The review's conclusion is that REDs appears ubiquitous in elite team ball sports but that research remains limited, and that a criterion approach is needed for accurate, reliable and consistent reporting [s1].

What the consensus statement already asks for

The 2023 IOC consensus statement is not silent on this. It introduced updated Health and Performance Conceptual Models and a new Physiological Model designed to capture the difference between problematic and adaptable LEA exposure, moderated by individual factors [s2]. It also introduced a REDs Clinical Assessment Tool, Version 2, which stratifies detection and diagnosis by accumulated severity and risk [s2], and it set out methodological best practices for REDs research explicitly to address knowledge gaps [s2].

The review published this month is, in effect, a measurement of how far the field has moved on those methodological recommendations in team sport. On the evidence of six methods across twelve studies, not far.

What this means for reading REDs numbers

When a figure circulates about how many athletes in a given league are energy deficient, the number that matters is not the percentage but the instrument. A study using the LEAF-Q will generally return a higher prevalence than one using a measured energy availability threshold, and both differ from a hormonal panel. None of the three is wrong; they answer different questions.

The distinction also matters clinically. Low energy availability is a state, potentially transient and sometimes adaptive [s2]. REDs is a syndrome with health and performance consequences. Screening tools are designed to flag risk for follow-up, not to diagnose. A headline prevalence figure collapses that structure.

The limits of this review

Fourteen studies across 12 sports and 265 athletes cannot support sport-specific or sex-specific conclusions, and the review does not attempt them. Ten of the fourteen were cross-sectional [s1], which means they capture a single moment inside a season — and energy availability in team sport plausibly varies enormously between pre-season, congested fixture periods and the off-season.

The searches were run in October 2024 [s1], so anything published in the year since is outside the review.

What to watch

The useful development would be repeated within-athlete measurement across a season using a single declared criterion, in enough athletes to say something about which phases of a competitive year produce deficiency. Until studies of that shape exist, the honest statement about REDs in team ball sport is that it is being detected wherever people look for it, at rates that depend mostly on how they look.

Sources

• [s1] Relative energy deficiency in sport (REDs) in elite adult team ball sport athletes: a systematic review — Journal of Science and Medicine in Sport, published online 22 October 2025. https://doi.org/10.1016/j.jsams.2025.10.011
• [s2] 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs) — British Journal of Sports Medicine, 2023. https://doi.org/10.1136/bjsports-2023-106994