Understanding RED-S: A Hidden Risk in Sport
- kirstenlawton5
- Sep 12
- 3 min read
'Relative Energy Deficiency in Sport (RED-S)' is a condition that can affect both elite & recreational athletes, children active in sport & anyone else that is training hard without adequate fuelling. If left unrecognised and untreated, it may drastically affect long-term performance and overall quality of life.
What is RED-S?
Relative energy deficiency in sport (RED-S) can happen when an athlete consistently does not consume enough calories to support their body’s energy demands.
Low calorie intake & excessive training over a period of time leads to low energy availability. During periods of low energy availability, your body must prioritise certain functions and typically these are the functions that are essential for life - such as breathing & heart function.
Many high energy functions that the body does not perceive as essential may slow down, which can lead to health complications.
What are the symptoms & signs?
Energy deficiency disrupts physiological functions affecting nearly every system in the body:
Metabolism and immunity: Increased illness and fatigue
Hormonal function: Menstrual irregularities in women; reduced testosterone in men
Bone health: Low bone mineral density, stress fractures and osteoporosis
Mental health & cognitive function: Anxiety, depression and poor concentration
Performance: Decreased endurance, strength and recovery
Other symptoms can include hair loss, low blood pressure and slow heart rate
Key RED-S prevalence stats
Up to 60% of female athletes in endurance sports (like running, cycling and dance) may experience low energy availability
Around 25–30% of male athletes in similar sports are also affected, though RED-S in men is often underdiagnosed due to lack of awareness.
The condition was originally referred to as the Female Athlete Triad but changed to RED-S in 2014 by the International Olympics Committee, to recognise it can affect anyone.
In adolescent athletes, bone stress injuries, a common consequence of RED-S, account for up to 20% of all sports-related injuries.
Why awareness matters
RED-S is often overlooked because early symptoms, like fatigue or frequent colds, can seem minor. Athletes may be praised for or even encouraged to adopt behaviours that contribute to RED-S, such as extreme discipline, weight loss & overtraining.
Inadequate nutrition is often unintentional, but the condition becomes more psychologically complex when undereating is intentional and training becomes compulsive. In some sports, such as those that emphasize weight or leanness, athletes may undereat to maintain a specific body shape and size that is required for competition. For other sports, the primary motivation may be to improve the strength-to-bodyweight ratio and performance.
Whilst the narrative is changing, I know that I come from an era where in running, "thin = fast" and recovery was not a factor in training - it was all 'go hard or go home'. In fact, I myself suffered a bone stress fracture which was likely a result of overtraining and consistent under fuelling.
So, whether you are an athlete, parent, coach, trainer or health professional, its important that we are familiar with the risks, recognise the signs and understand the importance of balanced nutrition and recovery.
If you’re training hard, (or know someone that is), ask:
Am I eating enough to match my energy output? Food is fuel - eat to match your training load
Am I recovering well—sleeping, feeling strong, staying injury-free? Rest and recovery is part of progress
Mild RED-S may be treatable with increased calorie intake alone, but athletes with prolonged or severe low energy availability, underlying disordered eating or an eating disorder & compulsive training needs might need to take time off from their sport and get professional support.
As a Soft Tissue Therapist, it is not within my scope of practice to diagnose or advise on RED-S, but I am able to advise on overuse injuries, can discuss your training & can provide treatment & rehab for injury. If you’re concerned about bone health, nutrition, eating disorders or low energy availability, please speak to your GP or seek advice from a Dietician or Nutritionist familiar with RED-S.
