Female athlete triad and RED-S
Too little energy for training causes the female athlete triad: low energy availability, menstrual dysfunction and low bone density. RED-S widens this to all athletes and body systems.
How low energy availability leads to bone loss
Low energy availability may come from disordered eating, deliberate dieting, or simply not eating enough for heavy training.
The triad as a spectrum (ACSM, 2007)
| Component | Healthy end | Unhealthy end |
|---|---|---|
| Energy availability | Optimal energy availability | Low energy availability, with or without an eating disorder |
| Menstrual function | Regular cycles (eumenorrhoea) | Functional hypothalamic amenorrhoea |
| Bone health | Optimal bone health | Osteoporosis |
Energy availability of a 400 m runner
Kavya, a 400 m runner, weighs 52 kg with 20% body fat. She eats 1750 kcal a day and uses 700 kcal in training. Find her energy availability and the intake she needs to reach 45 kcal/kg FFM/day.
- Fat-free mass = 52 × (1 − 0.20) = 52 × 0.80 = 41.6 kg.
- EA = (1750 − 700) ÷ 41.6 = 1050 ÷ 41.6 = 25.24 kcal/kg FFM/day, about 25.2.
- 25.2 is below 30, so her energy availability is low.
- Intake needed for EA 45 = (45 × 41.6) + 700 = 1872 + 700 = 2572 kcal.
- Extra energy needed = 2572 − 1750 = 822 kcal a day.
- Check: (2572 − 700) ÷ 41.6 = 1872 ÷ 41.6 = 45.
EA ≈ 25.2 kcal/kg FFM/day (rounded to one decimal), which is low. She needs about 2572 kcal a day, roughly 820 kcal more, or less training, to reach 45.
RED-S: effects on health and on performance
RED-S (Relative Energy Deficiency in Sport) was set out by the IOC in 2014 to show that low energy availability harms male athletes and the whole body, not just bone and periods.
Prevention and treatment
- Screen at pre-season medicals: menstrual history, weight changes, stress fractures, eating habits (questionnaires such as the LEAF-Q).
- Educate athletes, coaches and parents: missed periods are not a normal sign of hard training.
- Team approach: sports physician, sports dietitian, psychologist and coach.
- First step of treatment: raise energy intake and/or reduce training until periods return and weight is stable.
- Meet calcium (1000 mg/day, ICMR-NIN 2020) and vitamin D needs; continue sensible weight-bearing exercise.
- Avoid public weigh-ins and comments on body shape; refer eating disorders early.
- Return to full training in stages as risk falls.
A 15-year-old gymnast or distance runner whose periods stop is not 'just training hard': the dietitian checks energy availability, adds snacks around training (peanut chikki, banana with milk, curd rice), covers calcium and vitamin D, and works with the doctor and coach before full training resumes.
2 marks: “What is energy availability?” Dietary energy left for body functions after training: (energy intake − exercise energy) ÷ fat-free mass. Below about 30 kcal/kg FFM/day is low.
5 marks: “Write a note on RED-S.” IOC 2014 (updated 2018, 2023); cause is low energy availability; health and performance effects; affects men too; screening and treatment.
10 marks: “Explain the female athlete triad. Add its prevention and treatment.” Three components with a diagram, the spectrum, energy availability with a sum, effects on bone and performance, RED-S, then prevention and treatment.
Triad = E-M-B: Energy low, Menses lost, Bone weak. 45 healthy, 30 low (kcal/kg FFM).