Nearly half of all athletes tested in a massive 2024 review of sports research were found to be running on too little fuel for their bodies to function normally.
Quick Take
- The International Olympic Committee (IOC) formally recognizes Relative Energy Deficiency in Sport, known as RED-S, as a condition that can damage bones, hormones, immunity, and heart health.
- RED-S happens when an athlete burns more calories through exercise than they take in through food, leaving the body without enough fuel to run normally.
- A large 2024 meta-analysis of nearly 6,100 athletes found 44.7 percent had low energy availability, the root cause behind RED-S.
- Specialists point to intense training culture and constant pressure to do more as reasons athletes land in energy deficits without realizing it.
- The IOC has built a clinical screening tool to help doctors and coaches catch warning signs before they turn into serious injury or illness.
What RED-S Actually Is, According To The Olympic Committee
The IOC defines RED-S as impaired body function caused by a mismatch between calories eaten and calories burned during training. Its 2018 consensus statement lists damage across metabolism, menstrual health, bone strength, immune defense, muscle repair, and heart function as direct consequences of that gap. The condition was first named in the IOC’s 2014 statement, replacing the older “female athlete triad” model that focused mainly on women.
The science behind RED-S comes down to one equation. Energy availability equals the calories an athlete eats, minus the calories burned through exercise, divided by their fat-free body mass. When that number drops too low for too long, the body starts shutting down systems it considers less essential for survival, like reproduction and bone rebuilding, to protect vital organs.
How Many Athletes Are Actually Affected
A 2024 systematic review and meta-analysis in Sports Medicine pooled 59 studies covering more than 6,100 athletes. It found 44.7 percent had low energy availability, including 44.2 percent of women and 49.4 percent of men. Among athletes screened specifically for RED-S risk, 63 percent showed signs of the syndrome. A separate survey of 192 national-level athletes found 67.2 percent fell into the medium or high risk category, with weight-class and endurance-style sports showing the steepest numbers.
Those figures stretch across a wide range in other research too, with low energy availability reported anywhere from 23 to nearly 80 percent in female athletes and 15 to 70 percent in male athletes, depending on the sport and how it was measured. That spread shows the problem touches far more than one gender or one type of competition. It also shows researchers still lack one single test that works the same way for every athlete.
Why Hustle Culture Keeps Coming Up In The Conversation
Sports medicine voices increasingly connect RED-S visibility to a broader fitness culture built around nonstop effort. Men’s Health reporting ties rising public conversation about RED-S to “no days off” messaging and the popularity of appetite-suppressing medications that can mask hunger signals during heavy training. That framing is a reasonable read of the moment, even though no formal study has measured whether hustle culture itself is driving more cases rather than simply more awareness.
What is clear is that the IOC does not treat RED-S as a niche concern. The committee issued a renewed consensus statement specifically to protect athlete health as the science around energy deficiency has matured, stating the goal is prevention through better screening and education. That institutional push matters because it moves RED-S out of locker-room whispers and into official medical guidance that coaches and trainers are expected to follow.
You're going to hear a lot about REDs over the next couple of years.
*lots*
Yeah. Relative Energy Deficiency in Sport (REDs) sounds like long covid in athletes.
Fatigue.
Declining performance.
Poor recovery.
Immune dysfunction.
Cardiovascular problems.REDs is real, but if an… pic.twitter.com/qkhCtb2rA5
— tern (@1goodtern) October 20, 2026
What Comes Next For Screening And Prevention
The IOC’s newest clinical assessment tool sorts athletes into a red, yellow, or green risk category based on objective markers like bone density and hormone levels alongside secondary signs like injury history. That traffic-light system gives team doctors a faster way to flag athletes before a stress fracture or hormonal crash sidelines them for a season. Wider adoption of that tool across schools, colleges, and professional leagues remains the clearest path toward catching RED-S early instead of after the damage is done.
Sources:
menshealth.com, olympics.com, pubmed.ncbi.nlm.nih.gov, link.springer.com
