The Multidimensional Impact of Energy Deficiency and Low Energy Intake on Elite Female Athletes: A Systematic Review

Abstract

Study aim(s): This systematic review aims to provide a comprehensive examination of the multifaceted effects of low energy availability (LEA) and its progression to sport-related Relative Energy Deficiency in Sport (RED-S) on performance, recovery, injury risk, and long-term health outcomes in elite female athletes. Methods: This study was conducted as a systematic review in accordance with PRISMA standards. A comprehensive literature search was performed using keywords such as "RED-S," "LEA," "elite female athletes," "performance," "recovery," "injury risk," and "long-term health". Methodological quality and risk of bias (RoB) were assessed using appropriate tools, including the Cochrane RoB for randomized controlled trials and the Newcastle-Ottawa Scale for observational studies. Findings were then thematically synthesized into four primary domains: performance, recovery and metabolic function, injury risk, and long-term health. Results: The findings consistently demonstrate that LEA, the primary cause of RED-S, has significant adverse effects across multiple physiological systems. High prevalence rates of LEA and RED-S risk have been reported across various sports, particularly in aesthetic and endurance disciplines (e.g., 77.4% in football, 80% in athletes exhibiting at least one RED-S symptom across sports, and 41.6% in aesthetic sports). Key consequences include metabolic slowing, hormonal axes disruption, decreased bone mineral density, impaired vascular function, and an increased risk of both bone and soft tissue injuries. Furthermore, LEA and RED-S are associated with reduced power output and impaired recovery capacity, posing a serious threat to performance sustainability and career longevity. Conclusions: LEA is a key precursor to RED-S, presenting a significant multisystemic threat to the health and performance of elite female athletes. The well-established connection between LEA-induced energy deficits and serious physiological consequences underscores the need for early diagnosis and a structured, multidisciplinary management approach. Future research should focus on longitudinal study designs, standardized measurement protocols, and the identification of sport-specific energy availability thresholds to clarify causal relationships and inform evidence-based clinical practice.