How common is low energy availability in athletes?

In a 2025 systematic review and meta-analysis of 59 studies, 44.7% of athletes (2,737 of 6,118, across 46 studies) were classified as having low energy availability (LEA), meaning energy expenditure from training and bodily functions exceeded energy intake. In eight studies, 460 of 730 athletes (63.0%) were classified as at risk of relative energy deficiency in sport (RED-S). These are pooled study-level figures, not a rate for any one sport or athlete.

What did the meta-analysis of low energy availability find?

Gallant et al., Sports Medicine 2025 searched PubMed, Embase and Cochrane. Of 59 studies that met the inclusion criteria, 46 contributed to the LEA prevalence figure. By sex, LEA was reported in 44.2% of female athletes and 49.4% of male athletes. The abstract does not give the sample size for each sex, so that gap should not be over-read.

RED-S is described by the authors as a condition in which the energy deficit is severe enough to alter metabolic rate, menstrual function, immune function, bone health, protein synthesis and cardiovascular function. The 63.0% figure reflects athletes classified as at risk of it, across only eight studies, so it rests on far less data than the LEA figure.

A pooled prevalence blends together different groups of athletes and, potentially, different ways of classifying LEA. It describes the studies that were included, not all athletes, and the authors point to tools such as the Low Energy Availability in Females Questionnaire (LEAF-Q) for early identification.

What has low energy availability been associated with in athletes?

Athletes classified as having LEA showed decreased run performance, endurance performance, coordination and concentration, and more illness-related training absence. Most studies concluded that athletes with LEA had impaired bone health and a higher risk of bone stress injuries.

These are associations. A finding that LEA and a bone stress injury appear together in the same group of athletes does not show which came first or that one caused the other. The abstract also does not report how many studies looked at each outcome or how large the differences were, so these statements describe the direction of findings, not their size.

Protein, one part of energy intake, is covered in our post on the evidence for protein per kilogram.

The bottom line

• Across 46 studies, 44.7% of 6,118 athletes were classified as having low energy availability (44.2% of women, 49.4% of men).
• In 8 studies, 63.0% of 730 athletes were classified as at risk of RED-S, a smaller evidence base than for LEA.
• LEA was associated with lower performance measures and, in most studies, with bone stress injury: associations, not proof of cause.