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Understanding Female or Male Athlete Triad Compared to Relative Energy Deficiency in Sports

While the Female Athlete Triad may be better known among health professionals, there is evidence to support a comparable syndrome in males, and both conditions are distinct from Relative Energy Deficiency in Sports (RED-S).

Published July 28, 2023

The Female Athlete Triad was officially described in 1997 by the Task Force on Women's Issues of the American College of Sports Medicine (ACSM). This syndrome, often observed in physically active adolescent and adult females, represents a spectrum of three distinct medical disorders including disordered eating, amenorrhea and osteoporosis. The most recent consensus statement from the ACSM in 2017 uses new terminology to describe these three interrelated components: energy availability, menstrual function and bone health.

Energy availability, as defined by the ACSM, is the amount of energy leftover and available for normal body functions after the energy expended for training is subtracted from the energy taken in from food. Low energy availability may be unintentional or a symptom of disordered eating or an eating disorder. It may be common in weight sensitive sports where leanness and body weight are important due to their roles in performance, and these athletes may be at a greater risk of disordered eating. However, the ACSM states athletes of any sport may be affected by low energy availability.

While the Female Athlete Triad may be better known among health professionals due to its origin, energy deficiency among athletes is not unique to females. In fact, there is now an evidence base to support a comparable syndrome in males. Details of the Male Athlete Triad, which were published as a two-part consensus statement by the Female and Male Athlete Triad Coalition in 2021, indicate there is "strong evidence from RCTs [randomized controlled trials] and/or observational studies but with some inconsistent results from the overall conclusion" that adolescent and young adult males, who participate in endurance and weight-class sports, are at risk for developing one or more risk factors of the Male Athlete Triad.

The Male Athlete Triad includes energy deficiency or low energy availability (which may or may not be a result of disordered eating or an eating disorder), impaired reproductive health, and impaired bone health. The extent of energy deficiency is thought to be greater in males for it to have an impact on skeletal and reproductive health, but more research is needed regarding its impact in both sexes.

Prior to the inception of the Male Athlete Triad, the International Olympic Committee (IOC) acknowledged that energy deficiency could apply to any athlete, regardless of sex, when they introduced Relative Energy Deficiency in Sports, also known as RED-S, in 2014.

Normal body functioning is impaired in RED-S due to relative energy deficiency and can affect growth and development, metabolic rate, production of hormones, menstrual function, bone health, immunity, as well as hematological, cardiovascular, gastrointestinal and psychological health. In addition, RED-S may lead to a gradual reduction in the athletes' performance, including decreased endurance, coordination and concentration; increased risk of injury; poor response to training; and decreased glycogen stores and muscle strength. Symptoms relating to impaired cognition, irritability and depression also have been reported in athletes screened for low energy availability.

While gaps in research have been identified for each, all three models are currently used in practice. Implications of these conditions warrant that athletes receive expert guidance regarding nutrition and its relationship to physical activity, performance and recovery. Registered dietitian nutritionists specializing in sports nutrition are integral in conveying the complexity of the Female or Male Athlete Triad and RED-S, while working with a multidisciplinary team to help prevent and correct inadequate energy intake in athletic individuals.


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  • Academy of Nutrition and Dietetics. Sports Nutrition Care Manual. Eating Disorders, Overview. Accessed April 13, 2023.
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