Relative energy deficiency in sport (REDs).

Relative energy deficiency in sport (REDs) is a multisystem syndrome resulting from chronic low energy availability that impairs metabolic, reproductive, skeletal, cardiovascular, and psychological health in athletes of all genders. This article reviews the epidemiology and pathophysiology of REDs and outlines major complications, including low bone mineral density, stress fractures, infertility, and potential vascular dysfunction/cardiometabolic effects. Sex-specific considerations, including functional hypothalamic amenorrhea in females, are also explored. A practical diagnostic approach highlights focused history-taking, targeted laboratory evaluation, and application of the International Olympic Committee Relative Energy Deficiency in Sport Clinical Assessment Tool Version 2 for risk stratification. Management strategies center on restoring adequate energy availability through nutritional rehabilitation and training modification, supported by psychological care, optimization of calcium and vitamin D, and selective use of hormonal or bone-active therapies in refractory cases. Because many at-risk athletes first present to primary care, this article focuses on equipping clinicians with the knowledge and tools needed to recognize, evaluate, and manage REDs and to coordinate multidisciplinary care to prevent long-term morbidity.