Source notes

What happens when an athlete repeatedly uses more energy in exercise than their diet can support? Too little energy may remain for normal body functions, and prolonged or severe exposure can lead to relative energy deficiency in sport, or REDs. This guidance covers female and male athletes and distinguishes harmful under-fuelling from shorter, adaptable reductions in energy availability. Its evidence update included around 178 research publications involving about 23,822 participants. The central message is that health and performance effects depend on the exposure and the individual, rather than a single calorie threshold.

Low energy availability and REDs are related but not interchangeable. The first describes an energy mismatch; the second describes resulting disruption to physical or psychological functioning. Responses can differ across body systems and athletes. Mental health can contribute to the problem or be affected by it. No single test definitively diagnoses the syndrome, and other explanations for symptoms need consideration.

How Does This Show Up in Real Life?

An athlete who increases training without enough additional food may face a different problem from simply having a difficult training week. Menstrual disruption, recurrent bone stress injuries or declining performance can contribute to a clinical assessment, but none proves REDs by itself. The statement recommends a physician-led process that brings together symptoms, examination and relevant tests. Its risk categories help clinicians guide participation and treatment; they are not a self-diagnosis checklist. Treatment aims to restore adequate energy availability through changes to nutrition and exercise, with appropriate dietary and psychological support. The paper also cautions against treating a particular body composition as a universal performance target. Decisions about body measurements should consider the athlete's health, consent and circumstances.

Much of the newer evidence was observational: roughly 62% of studies were cross-sectional, and 80% of participants were female. These imbalances limit causal conclusions and knowledge about some athlete groups. Recovery can differ between systems; improved reproductive function does not guarantee simultaneous bone recovery. The guidance does not offer one recovery deadline that applies to everyone.

Why We Cite It

Alpekin can use this statement to assess whether discussion of sporting performance gives adequate weight to the demands of growth and normal physiology. It also provides a framework for distinguishing a nutrition claim aimed at a general reader from a situation requiring coordinated clinical care and decisions about safe participation.

The statement offers a substantial clinical framework, while recognizing gaps in diagnosis and research. Its practical value lies in taking a pattern of concerns seriously and assessing it in context, without reducing a complex health problem to weight, a food calculation or one symptom.