What is Low Energy Availability?
Energy availability is defined as the amount of energy available to the body for essential function, after accounting for expenditure during exercise or training. Essential functions includes, but are not limited to:
- Digestion
- Cardiac function
- Cognitive function
- Muscle repair
- Immune strength
- Maintenance of bone health
- Hormone production
When the energy we consume from food and drink does not match the needs of exercise and everyday living, an energy deficit is created. If this deficit is severe and lasts long enough it can lead to a situation known as low energy availability (LEA).
As a result of insufficient energy being available the body’s systems have to adapt to the lower energy levels, which compromises and reduces the energy available to the body for key functions such as bone health, reproduction, and immunity.
Who is at risk of LEA?
LEA is more common in individuals who participate in sports:
- That are endurance based or where weight and/or leanness are believed to be good for performance (e.g. Triathlon, distance running, cycling)
- Where a weight category is implemented for competition (e.g. light-weight rowing, weightlifting, wrestling, boxing, combat sports).
- Where aesthetics/appearance is judged (gymnastics, dancing)
However, LEA can occur with any body type, at any body mass and in both men and women. Any individual exercising is at risk of developing LEA.
What causes LEA?
Accidental LEA may be due to:
- An increase in training volume and/or intensity
- Lack of time, skills or money for food planning and preparation
- Eliminating foods/food groups
- Not understanding the individual energy needs for sport
LEA can also result from disordered eating behaviours or eating disorders.
What are the signs of LEA?
- Frequent or repeated illnesses (e.g. coughs, colds, skin infections, stomach bugs)
- Recurring injuries that do not get better (e.g. stress fractures)
- Tired, sluggish, not recovering from training
- Absent or irregular menstrual periods
- Poor concentration, reduced interest, low mood
- Under performing in training and competition
LEA is not always accompanied by weight loss. The body is able to conserve energy for survival and can maintain overall body weight even when there is not enough energy. One method is shutting down or reducing function ‘non-vital’ body systems such as those responsible for the menstrual cycle, immune health and bone health to save on energy.
How do you prevent LEA?
- To prevent LEA a diet should provide enough energy to support the demands of exercise and life – this allows for optimal health, training adaptation, recovery, and performance.
- If there is an increase in training volume or intensity, energy intake should also increase to match the increase in energy expenditure.
- Understanding the energy value of food and the demands of exercise helps ensure athletes have a healthy approach to energy requirements.
- Be cautious of information and trends on social and mainstream media.
- Seek support from a qualified Sports Dietitian to ensure you are meeting your needs.
What is RED-S (Relative Energy Deficiency in Sport)?
Relative Energy Deficiency in Sport (REDS), is a syndrome which can adversely affect the health and performance of athletes. It exists when under-fueling is sustained for extended periods of time (there is a negative balance between dietary energy intake and the energy expenditure required to support optimal health, daily living activities, growth, and sport). This can result in many negative health and performance outcomes. The underlying cause of REDS is low energy availability.
What is the link between REDS and LEA? REDS is caused by low energy availability.
Signs and symptoms of RED-S:
- Menstrual dysfunction
- Fatigue, low energy
- Altered mood, poor concentration
- Decreased performance or failing to improve
- Recurrent injuries and illness
- Loss of enjoyment from sport
- Low mood
- Lack of normal growth and development
Who is at risk of RED-S?
RED-S may affect both females and males. Recreational athletes have been shown to have a higher prevalence of low energy availability (and therefore risk of RED-S) than their elite counterparts (which might reflect the education and support available for elite athletes).
All athletes, regardless of age, gender, sport, body size, participation, or achievement in sport are susceptible to developing low energy availability, the underlying cause of RED-S.
Prevention of RED-S:
The key to preventing REDS includes ensuring an adequate energy intake in relation to exercise needs. This may include:
- Fuelling across the day with regular meals, snacks and recovery options that contain appropriate nutrients and total energy (calories).
- Identifying training days across a week and training phases throughout a year where energy requirements may be increased.
- Avoiding prolonged periods without eating and optimise pre, during and post training or competition nutrition to promote appropriate energy availability
A Sports Dietitian can assist in ensuring the energy you are consuming is appropriate for the demands of your sport.
At The Injury Clinic Physiotherapy, we are luck enough to have a Sports Dietitian as part of the team. If you’re in need of nutritional advice, please don’t hesitate to contact us to arrange an appointment.
If I think I have RED-S or have been diagnosed with RED-S what should I do?
Engage with a Sports Doctor, Sports Dietitian and potentially a Psychologist. Depending on duration and severity of symptoms a plan will be developed where energy intake will be increased and there may be a period of decreased exercise. The key reasons for developing REDS will be identified and managed through education and/or psychological support.
Will I gain weight as a result of eating more and will this then impact my performance negatively?
In some cases weight gain will be necessary for health and performance. In many cases, improving energy availability can be achieved without gaining much weight. One of the effects of REDS is a reduction in resting metabolic rate, therefore improving energy availability actually leads to increased resting metabolism.
References:
Gallant, T. L., Ong, L. F., Wong, L., Sparks, M., Wilson, E., Puglisi, J. L., & Gerriets, V. A. (2025). Low Energy Availability and Relative Energy Deficiency in Sport: A Systematic Review and Meta-analysis. Sports medicine, 55(2), 325–339. https://doi.org/10.1007/s40279-024-02130-0
Mountjoy. M., Ackerman K. E., Bailey, D. M., Burke, L. M., Constantini, N., Hackney, A. C., Heikura, I. A., Melin, A., Pensgaard, A. M., Stellingwerff, T., Sundgot-Borgen, J. K., Torstveit M., K., Jacobsen, A. U., Verhagen, E., Budgett., Engebretsen, L., & Erdener, U. (2024). 2023 International Olympic Committee’s (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine, 57, 1073-1098. doi:10.1136/bjsports-2023-106994
Mountjoy, M., Sundgot-Borgen, J., Burke, L., Carter, S., Constantini, N., Lebrun, C., Meyer, N., Shrman, R., Steffen, K., Budget, R., Ljungqvist, A., & Ackerman, K. (2015). The IOC relative energy deficiency in sport clinical assessment tool (RED-S CAT). British Journal of Sports Medicine, 49(21),421-423. https://doi.org/10.1136/bjsports-2014-094559
