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Relative Energy Deficiency in Sports

The body works like a car engine and just like cars need petrol or diesel to run we need energy from food and fluids. However, there is much more to consider than a simple balance between matching energy intake and energy output from exercise.

Obviously our bodies not only use energy for exercise but also for basic bodily functions, mainly to keep our brain and other organs working.

However, there is much more to consider than a simple balance between matching energy intake and energy output from exercise. It’s important to also consider your clients energy needs to support health and wellbeing, as there are negative health consequences of being in an energy deficient state. Rather than energy balance, energy availability (EA) is the term used to describe the amount of energy (calories) left for bodily functions (growth, development, immune function, menstruation), after the energy used up in exercise has been deducted.

What is RED-S?
Relative Energy Deficiency in Sports (RED-S) is a syndrome where there is a mismatch between the amount of energy the athlete puts into their body from food & fluids and the energy used up in exercise. The food consumed simply doesn’t provide enough energy to fuel normal bodily functions and exercise. If the athlete is a highly active individual the body tries to fuel training and save energy by reducing the effectiveness or stopping some processes in the body. Some of these disrupted body functions can include impaired menstrual function, compromised bone health, decreased immunity, and reduced resting heart health. For highly active people this can also mean a greater risk of injury.
How does RED-S occur?
Low Energy Availability (LEA) occurs when there isn’t enough energy left over after exercise to support the body’s normal healthy functions. LEA can occur in the following ways;

  • Under-fuelling (not consuming enough energy from food and fluids)
  • Overtraining (using up too much energy in exercise)

What are the potential health consequences of RED-S?
The image below illustrates the potential health consequences of RED-S which can affect your client in a number of ways;

  • Reduced strength and endurance
  • Increased injury risk
  • Reduced metabolic rate
  • Reduced training response
  • Increased depression or irritability
  • Reduced fertility

The illustration above is adapted from Constantini NM., 2002.
What are the signs and symptoms of LEA? RED-S?

  • No period >3 months (irregular / absent menstrual cycle)
  • Overly restrictive intake / disordered eating – eating less than needed
  • Stress fractures / low bone density
  • Depressed mood/feeling irritable
  • Frequent illness
  • Decline in performance
  • Always feeling tired and fatigued

How common is RED-S?
Recent research in Ireland revealed 40% of active Irish females surveyed were at risk of LEA. The risk is higher in those involved in competitive sport compared to recreationally active females. Those at risk of LEA were 3 times more likely to have missed over 22 days of training due to illness.

What can you do to prevent RED-S in your clients?

  • Ensure they are fuelling their body with sufficient energy from food and fluids. Ways to increase their caloric intake include the following;
  • Ensure they understand how many calories they need to support daily living and their training schedule
  • Advise or discuss bigger meal portions
  • Increasing meal frequency – include snacks between meals to create another eating opportunity
  • Advise them to make milk-based smoothies to provide energy in liquid form if they don’t feel like eating more
  • Include foods which are energy-dense such as nuts, nut butters, avocado, hummus, olive oil.

RED-S is a double-edged sword as it can stop your clients from training or performing to the best of their ability but it may also affect their health. Ensuring they are aware of their daily caloric needs is the first place to start followed by making them aware of both the symptoms and negative health consequences should it occur. Identifying clients you feel may be at risk and simply having a chat to see how they are eating and feeling will help you verify if RED-S is an issue and you can then implement some of the above strategies to help them overcome it!
If you’re a personal trainer or sports coach and haven't already signed up to our online nutrition course, then Sign up today! The course consists of ten online modules and on completion of these, you will receive an accredited certificate in Nutrition by the Association for Nutrition (AfN) and earn CPD points from your professional body.

NOTE: The following information is for educational purposes only and does not reflect the opinion of Glanbia Performance Nutrition, nor is it intended for product marketing purposes.

1.Mountjoy M, et al. 2018. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Br J Sports Med.
2.Loucks AB, Thuma JR. 2003. Luteinizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women. The Journal of Clinical Endocrinology & Metabolism.
3.Stand P. et al., 2007. The female athlete triad. Med Sci Sports Exerc.
4.Drew MK, et al. 2017. A multifactorial evaluation of illness risk factors in athletes preparing for the Summer Olympic Games. Journal of science and medicine in sport.
5.Logue DM, et al., 2019. Screening for risk of low energy availability in athletic and recreationally active females in Ireland. European journal of sport science.