top of page

Relative Energy Deficiency in Sport (RED-S)

Updated: Nov 14, 2023

As I mentioned in our previous Pelvic Health Update, RED-S is a condition that I am seeing increasingly through my work and a topic that can be really influential and career changing for athletes but also anybody who trains as part of a healthy lifestyle. Below I have provided a brief overview of RED-S and how it can be recognised and managed, let me know what you think!

What is RED-S?

RED-S refers to impaired physiological functioning caused by a relative energy deficiency. This means that a person’s nutritional intake and recovery from sport or activity is not adequate to support their energy expenditure at their level of training and day to day functioning. This can affect:

· Metabolic rate

· Menstrual function

· Immunity

· Bone health

· Cardiovascular health

Psychological issues can be both an effect of RED-S but also contribute to the cause of it. When it comes to athletes, there can be significant and profound effects on their performance, including but not limited to:

- Decreased muscle strength

- Decraesed endurance performance

- Decreased training response

- Impaired judgement

- Decreased coordination

- Irritability

- Depression

- Increased risk of injury

A classic presentation of RED-S in clinic might be an athlete who has recently increased their training load and not necessarily matched their nutrition accordingly. These clients often then start to suffer from some of the above effects, notably a decreased training response and performance in their sport, which in turn leads to them increasing their training load further and limiting recovery time in order to make up for it. This simply doesn’t work and actually feeds into the issue of RED-S and makes the effects more profound. The longer this cycle goes on, the more likely it becomes for the client to go on to develop more serious injuries and consequences.

Menstrual Function

Whilst RED-S is apparent in both male and female athletes, it is more prevalent in females. An endocrine (hormonal) response occurs when an athlete becomes deficient in energy. Two hormones (LH and FSH) which increase during our menstrual cycle become supressed and this can then result in oestrogen deficiency. The disruption of these hormones can often present with a loss of menstrual cycle termed as Secondary Amenorrhoea. There are various conditions that can cause a change in these hormones, polycystic ovarian syndrome (PCOS) being a leading cause. In RED-S the term for the cause is Functional Hypothalamic Amenorrhoea.

Diagnosis of RED-S

RED-S often presents in physiotherapy clinics, however, to fully confirm a diagnosis a referral to an endorcrine specialist is needed. When we have athletes present with some symptoms of RED-S it is important we gain a full history and so may ask questions that fall outside of the questions you may be expecting your physiotherapist to ask you. It is critical to gain a good understanding of a client’s menstrual cycle as well as an in depth knowledge of their training load and recovery to allow appropriate management. An endocrine specialist will initially want to rule out any other condition that may be causing your symptoms. They will likely look into levels of certain hormones and vitamins in your blood and if you are experiencing recurrent injuries or stress fractures or have had a prolonged period of time with no menstrual cycle a bone health scan (DXA scan) may be appropriate.

Management of RED-S

Athletes with moderate to more sever RED-S should be managed by a team of healthcare professionals in order to correct the relative energy deficit by increasing their nutritional intake and/or decreasing their energy output. Some athletes may have to take time out of their sport, although often they already are due to injury or pain. Management can be complex and depending on severity can be lengthy, particularly around the emotional effects of prolonged restrictive eating and excessive training.

As the athlete recovers, their hormone levels will be retested and often their bone scans will be repeated at 6-12 month intervals in order to be sure their return to sport will not result in further damage occurring. A risk assessment may be used in order to ascertain an athlete’s readiness to return and this would ensure the return was as safe and effective as possible.

Use of hormonal contraception

There is ongoing research into the effect of hormonal contraception on women and whether it should be used to manage amenorrhoea. It has been found that the hormonal contraceptive pill should NOT be used for the treatment of RED-S (BJSM, 2018)

So what does this mean for me?

If you are reading this as an athlete or as somebody who has upped their training recently or are experiencing any symptoms of RED-S, take a moment to consider whether your nutrition intake has increased to match. Recovery days are also important as this gives your body time to heal and be prepared for you to go again in order to improve your fitness and work on your goals. Social media and other lifestyle factors can make us feel that if we aren’t training constantly, every day that we may fall behind whilst others get ahead. In reality, you will gain more in the long run by managing these 3 key aspects of training load, nutritional intake and recovery optimally.

If you are concerned by any of your symptoms or want to discuss this further, please do get in touch with one of our physiotherapists in order to make sure you can get on the right path to recovery or click on the button below for more information.


Br J Sports Med 2015;49:421–423. doi:10.1136/bjsports-2014-094559

285 views0 comments

Recent Posts

See All


bottom of page