Spotting the Signs: How to Identify Relative Energy Deficiency (REDs) in Athletes

The IOC has recently updated their guidelines (IOC paper) from 2014 to provide us with more detailed information on how to recognise and treat Relative Energy Deficiency in Sports (REDs). They also provide a really useful diagram to identify potential symptoms. Recognising RED-S can be challenging as many of the symptoms individually might be interpreted differently. REDs is also relatively new, only being labeled in 2014 so clinicians can misinterpret symptoms. Additionally, measuring energy intake (EI) and energy expenditure (EE) is often mostly estimated so it is only when a symptom manifests that REDs is hopefully diagnosed and treated.

1. Body Composition

Changes in body composition can be an initial indicator of REDs, although you might also see no weight changes, despite under fuelling. For some people, this might be one of their first indicators, especially if the weight loss is rapid or happens alongside an increase in training with severe restriction in intake. It is important to understand that you might still be within the NHS healthy BMI range to see the side effects of low energy availability (LEA) and REDs. It is usually the combination of changes in body composition with low carbohydrate availability (LCA) and an increase in exercise that all precipitates problematic LEA and ultimately REDs.

2. Primary or Secondary Amenorrhea

A particularly noticeable sign of REDs in women is the absence of menstruation. In adolescents, it is potentially concerning if menstruation hasn’t started by the age of 15. For those who have already started menstruating, a sudden stop in periods can indicate an issue. This cessation suggests that the body is conserving energy due to insufficient intake, prioritising other functions over the reproductive system. It is also concerning if menstruation is sporadic or intermittent. Neglecting this issue can lead to detrimental effects on bone health, which is always a crucial concern.

3. Injuries or Stress Fractures

Often, the journey to addressing REDs begins with the occurrence of injuries or stress fractures. This highlights the importance of sports doctors and physiotherapists being well-informed about RED-S and its symptoms. A stress fracture can occur from an increase in physical activity that is not matched by a corresponding increase in nutritional intake. This kind of injury serves as a crucial indicator that changes in diet or exercise routines may be indicated.

4. Hypothyroidism

In REDs, hypothyroidism is a result of the body trying to conserve energy. It is due to insufficient calories being taken in compared to energy expenditure and so the body slows down its metabolic rate to conserve energy. A sign of hypothyroidism is that you could be feeling extremely tired all the time and lacking in energy.

Any of the above symptoms might not definitively diagnose you with REDs, but they are potential warning signs especially when seen with more than one symptom.

How to Support Recovery

Nutrition and rest are the two very important aspects of recovery. Many people notice, for example, that they suffer with amenorrhea while increasing training, but periods resume over holidays or when training is less intense. This demonstrates that the balance between energy intake (EI) and energy expenditure (EE) is correct during low training periods but incorrect with increased training.

When considering nutrition, I categorise this into 3 categories:

  1. Overall calories.
  2. Overall carbohydrate intake
  3. Timing
Relative Energy Deficiency in sports pyramid

1. Overall Calories

Overall calories in needs to meet overall calories out. Usually, when we get the macronutrient balance right, the overall calories are also correct.

2. Carbohydrates

In sports, carbohydrates are king! There is an increasing over focus on protein and while protein is important, the ratio of protein to carbs is anywhere between 3:1 or 5:1 as a minimum. As a result, carbohydrates should make up 50% of the diet, predominantly coming from complex carbs, such as rice, pasta, bread, cous cous, oats etc. For snack ideas, I have created a detailed list of snack options based on 20g or 30+g carbohydrates and the link to purchase that can be found here:

3. Timing

It is important not to train fasted. It often feels hard having something to eat prior to going out to train, especially early in the morning, but it is really important to train your gut to manage this. A banana or 2 dates provides 20g carbohydrates and can make all the difference to a 30min training session. Anything longer, I would suggest the banana and dates or a slice of toast with banana to ensure adequate carbs prior to training. It is absolutely fine to have this 30min-1hr prior to your training session.

If you believe you are struggling with REDs, you are welcome to book a 1:1 appointment with me by following the online booking process or you can email the clinic: You can also listen to a podcast where I discuss all things carbohydrates. You can also watch my YouTube video where Polina interviews me on all things sports nutrition.

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