Exercise without proper nutrition can lead to a syndrome called relative energy deficiency in sport (RED-S). Athletes at greatest risk of RED-S are those who restrict intake, exercise for extended periods, and limit the types of foods that they will eat. Early detection of athletes at risk of RED-S is essential to prevent long-term consequences; however, validated screening tools for RED-S are limited. Often, athletes will present with a consequence of RED-S, such as a bone stress injury, amenorrhea, or performance impairments. Initial management for RED-S should be focused on increasing energy availability either by increasing caloric intake or decreasing energy expenditure during exercise. Prevention of RED-S should be a priority for coaches, parents, physicians, and sport organizations, but knowledge on this condition often is limited.

Case 2. GA is a 19-year-old collegiate cross country runner who comes to your office for menstrual abnormalities. She adopted a vegetarian diet approximately 6 months ago. She runs approximately 60 miles/week. Menses onset was at age 17 years. She has only had 4 periods in the past 12 months. She has never had a stress fracture. She is wondering if she should start taking birth control pills to help her have a period. She is not sexually active.

RED-S and the Female Athlete Triad

It is widely known that consistent participation in physical activity can have numerous health benefits. What is less publicized is that exercise without proper nutrition can lead to deleterious health outcomes, a syndrome called relative energy deficiency in sport (RED-S). RED-S refers to the physiologic disturbances caused by low energy availability.³⁶ Failure to consume enough dietary energy to account for the energy spent in exercise and daily living can lead to a state of low energy availability. This can occur because of inadvertent undereating, disordered eating, or a clinical eating disorder.³⁷