Relative Energy Deficiency in Sport (RED-S) in Physique Athletes and Strength Sports: Hormonal, Skeletal, Psychological and Performance Implications

Abstract

Background. Relative Energy Deficiency in Sport (REDs) is a multisystem condition associated with problematic low energy availability (LEA). Physique and strength sports may increase susceptibility due to prolonged energy restriction, intensive training, and pressure for extreme body composition.

Aim. To review current evidence concerning RED-S in physique athletes and strength sports, with emphasis on endocrine alterations, bone health, physical performance, psychological and behavioral consequences and clinical assessment.

Material and methods. A narrative search of PubMed, supplemented by relevant International Olympic Committee (IOC) consensus statements and publications in the British Journal of Sports Medicine, was undertaken using terms related to RED-S, LEA, bodybuilding, physique athletes, strength sports, hormonal function, bone health, and performance. Consensus statements, systematic reviews, meta-analyses, and primary studies were prioritized.

Results: Contest preparation may be associated with endocrine, metabolic, psychological, skeletal, and performance-related changes, including reductions in testosterone, thyroid-related hormones, IGF-1, and selected performance measures. However, direct evidence of REDs remains limited, with most studies being small, observational, or based on case reports.

Conclusions: Physique sports may create conditions conducive to problematic LEA and REDs. Clinical assessment should integrate multiple physiological, psychological, behavioral, and performance-related indicators rather than relying on a single biomarker or energy-availability threshold.