What is REDs?

If you're involved in athletics, you may have heard the term REDs being talked about more and more in recent years. But what exactly does it mean?

REDs stands for Relative Energy Deficiency in Sport. At its core, it's about a mismatch between how much energy an athlete is taking in (through food) and how much energy they are expending (through training and daily living). When the gap becomes too wide and continues over time, it can impact the body in ways that go far beyond just feeling tired.

The Definition

The International Olympic Committee (IOC) 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. 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 well-being, increased injury risk and decreased sports performance.”

How Common is REDs?

REDs is not a rare issue. Studies estimate that between 23% and 79.5% of female athletes and 15% to 70% of male athletes experience low energy availability (LEA) or REDs. The wide range comes from differences in sport type, level of competition, and how REDs is measured, but the numbers make one thing clear: this is not a fringe issue, it’s a common reality for many athletes.

Why it Matters

REDs isn’t just about eating less than you burn—it’s about how that imbalance affects an athlete’s entire system. It can influence training adaptations, long-term health, and athletic performance. And because the symptoms can vary so much, REDs often goes unrecognized or is misattributed to “normal” parts of training.

Citation

Mountjoy M, Ackerman KE, Bailey DM, Burke LM, Constantini N, Hackney AC, Heikura IA, Melin A, Pensgaard AM, Stellingwerff T, Sundgot-Borgen JK, Torstveit MK, Jacobsen AU, Verhagen E, Budgett R, Engebretsen L, Erdener U. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023 Sep;57(17):1073-1097. doi: 10.1136/bjsports-2023-106994. Erratum in: Br J Sports Med. 2024 Feb 7;58(3):e4. doi: 10.1136/bjsports-2023-106994corr1. PMID: 37752011.