Interventions for Relative Energy Deficiency in Sport Beyond Menstrual Recovery: A Systematic Review of Performance, Injury, Illness, and Mental Health Outcomes

Relative Energy Deficiency in Sport (RED-S) is a syndrome of impaired physiological and psychological functioning caused by problematic low energy availability, affecting athletes of all genders and across sport types. While menstrual recovery is a well-recognized clinical marker in females, decision-making in sport medicine also requires evidence on outcomes that directly influence health and performance, including physical performance, injury and illness risk, and mental health. This systematic review will synthesize evidence on interventions for RED-S that target outcomes beyond menstrual recovery. Using the PICO framework, we will include athletes and physically active individuals with RED-S or low energy availability (Population) receiving any nutritional, behavioral, training, multidisciplinary clinical, or policy-level intervention intended to treat or mitigate RED-S (Intervention), compared with usual care, no intervention, alternative intervention, or baseline (Comparison), and reporting at least one eligible outcome related to performance, injury, illness, or mental health (Outcomes). We will search Scopus, Web of Science Core Collection, PubMed/MEDLINE, SPORTDiscus, and CINAHL, plus targeted grey literature. Two reviewers will independently screen studies, extract data, and assess risk of bias using design-appropriate tools. Where feasible, random-effects meta-analysis will be conducted; otherwise, structured narrative synthesis will be used. This review will clarify which interventions improve clinically and practically meaningful outcomes in RED-S, identify evidence gaps, and inform clinicians, coaches, and policy stakeholders on effective strategies for protecting athlete health while supporting safe performance.