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Relative energy deficiency in sport (RED-S)

What is relative energy deficiency in sport? (RED-S)

Relative energy deficiency in sport, or RED-S for short is a syndrome caused by excessive amounts of exercise, inadequate energy intake or a combination of the two. RED-S tends to negatively impact on both an athlete’s ability to perform, and their general health.

RED-S is a relatively new term - prior to 2014 it was known as the female athlete triad. The female athlete triad focused on three main areas: low energy availability, associated with menstrual changes (irregular periods or loss of period altogether) and bone density changes (potentially leading to conditions such as osteoporosis.

In recent years, the effects of large volumes of training coupled with inadequate energy intake have been seen in men as well as women, which is one of the reasons why it is now called RED-S. It is now known that low energy availability is associated with many other negative effects on the body in addition to those originally included in the female athlete triad.

RED-S and low energy availability

Energy availability is a term used to describe the amount of energy (in the form of dietary intake) the body has for certain functions. RED-S occurs when the body is in a state of low energy availability. This means that after accounting for certain energy costs such as exercise, the body no longer has enough energy left for normal functions such as metabolic or immune function.

You might expect when you aren’t consuming enough food to meet your body’s energy needs weight loss would occur. While this can be the case, it’s important to keep in mind that even if you are in a state of low energy availability, you may not experience weight loss. This is because the body will reduce the amount of energy it uses on body functions in an effort to maintain energy balance.

How do I know if I am experiencing RED-S?

RED-S can affect men and women, and is associated with a wide variety of signs and symptoms. Athletes potentially experiencing RED-S may not notice all of the possible symptoms, and only have a couple of changes in their health or performance in earlier stages.

Possible health related symptoms of RED-S include:

  • Fatigue

  • Weight loss

  • Getting sick frequently

  • For women, changes in menstrual function (i.e. missing a period or having no period)

Possible performance related signs of RED-S include:

  • Frequent injures

  • Lack of progress in training, or even reversal of fitness indicators (e.g. reduced strength or speed)

  • Suboptimal performance

  • Reduced concentration levels

Long term consequences of RED-S

There are potential long-term consequences of RED-S, if left untreated. These include low bone density which may lead to conditions such as osteoporosis. Long term fertility issues may also occur. However, when treated early the health issues related to RED-S are reversible. Therefore, working to restore your energy imbalance is a high priority.

I think I might be experiencing RED-S. What do I do?

If you think you might be experiencing RED-S, it is important that you seek the assistance of your GP and a dietitian with experience in sports nutrition. If you have a coach or trainer, they will also be able to support you alongside your health professional team.

Your team will work with you to restore your energy balance, by modifying your food intake and exercise levels. Each person is different, so it is important that you receive individualised advice for your specific health and sporting needs.

If you think you might be at risk of RED-S, or you would like to find out more about nutrition and sports performance, you can make a booking with us at

- Ellen Payne, Accredited Practising Dietitian (APD) References:

  1. Mountjoy M, Sundgot-Borgen JK, Burke LM, et al. OC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. British Journal of Sports Medicine 2018;52:687-697.

  2. Mountjoy M, Sungot-Borgen JK et al. Relative Energy Deficiency in Sport (RED-S) Clinical Assessment Tool (CAT). Br J Sports Med 2015;49:421–423. doi:10.1136/bjsports-2014-094559

  3. Keay N, Rankin A. Infographic. Relative energy deficiency in sport: an infographic guide. British Journal of Sports Medicine 2019;53:1307-1309.

  4. Wasserfurth, P., Palmowski, J., Hahn, A. et al. Reasons for and Consequences of Low Energy Availability in Female and Male Athletes: Social Environment, Adaptations, and Prevention. Sports Med - Open 6, 44 (2020).


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