When Living Lean Goes Too Far... Relative Energy Deficiency In Sport And What You Need to Know About It

When Living Lean Goes Too Far... Relative Energy Deficiency In Sport And What You Need to Know About It

I remember being 4 weeks out from my first body building comp, looking in the mirror and almost crying beacuse 'I wasn't lean enough'. Compliments flowed about the physique I had achieved through months of hard training and energy restriction and yet I couldn't press two 9kg dumbells over my head (where these days 60kg push press is the norm). My menstrural cycle had stopped, I was lethargic, short fused and my enjoyment of training has all but faded away. What was looked like 'peak health' was quite the opposite, but I had to hang on until comp day. 

Fast forward 9 years and I now know many of the symptoms I was experiencing leading into my body building comps were signs of Relative Energy Deficiency in Sports (RED-S), and cluster of effects that result from under eating and over training. Information on this topic is much more readily available these days, and I have invited Accredited Practcing Dietitian and PhD candidate Claire Flower to share her expertise on the topic of RED-S in the following blog post- I hope you Enjoy! 

Relative Energy Deficiency in Sport (RED-s)

A term commonly used today in sports nutrition is RED-s or relative energy deficiency in sport. This occurs when the body has inadequate energy remaining to support the functions required for optimal health when there is additional energy being used for sport performance. The International Olympic Committee termed RED-s “impaired physiological function including, but not limited to, metabolic rate, menstrual function, bone health, immunity, protein synthesis, cardiovascular health caused by relative energy deficiency.”

Cause and consequences of RED-s

RED-s occurs in a state of ‘Low Energy Availability’. Energy availability is the amount of energy remaining for physiological functions after accounting for energy expended during exercise. Low energy availability occurs when there is less energy in compared to energy out causing there to be a limited amount of energy remaining for physiological functions. This leads to RED-s which can lead to a number of performance and health consequences such as those listed in the table below. These occur as a result of the body adapting through reduced bodily functions to conserve energy to decrease the imbalance.


Health Consequences

Performance Consequences

Bone health

Menstrual function








Growth and development

Decreased endurance performance

Decreased muscle strength

Decreased training response

Decreased glycogen stores

Increased injury risk

Impaired judgement

Decreased coordination

Decreased concentration



(Mountjoy et al., 2014)


What leads to the occurrence RED-s/Low Energy Availability?

Low energy availability and consequently RED-s can occur in athletes and active individuals due to a number of different reasons. On one hand it may be due to a low energy intake caused by following restrictive eating patterns, making poor food choices, not fuelling appropriately for exercise and having a lack of nutrition education/awareness. It can also occur due to an increased energy expenditure caused by an increase in the load or frequency of exercise. Common scenarios that can unintentionally lead to RED-s include busy individuals with a high training load but minimal opportunities to eat, or individuals who increase their training load without the knowledge to adjust their nutrition intake accordingly.

Who is at greatest risk of RED-s?

RED-s does not discriminate between populations. Initially it was assumed that Low Energy Availability and the related consequences only occurred in female athletes who compete in sports preoccupied with attaining a lean body composition to improve performance, such as gymnastics or triathlons. It has since been shown that RED-s occurs in males as well as females, and across all sports. Anecdotally it has been found that RED-s and low energy availability are prevalent in recreational athletes and the everyday individual. Within society there is often pressure to “eat less and move more” or to “reduce calories”, both which can be quite detrimental, especially for those who take part in high intensity exercise and do not match nutrition intake to the amount of exercise performed.

Questions to ask yourself if you are concerned about experiencing RED-s:

  • Am I constantly fatigued? Do tasks feel like more effort than they should?
  • Has my sport performance plateaued?
  • Have I missed any menstrual cycles lately?
  • Am I consistently sick or injured?
  • Is my weight stable despite eating a low amount of calories?
  • Am I getting an upset stomach/gastrointestinal issues?
  • Is my sex drive/libido low?
  • Is my mood low? Am I often grumpy and easily upset?
  • Am I preoccupied with food and body image/weight?

If you have answered ‘yes’ to one or more of these questions it may be a good idea to work with a dietitian and other relevant health professionals to address the symptoms you are experiencing.

How to avoid RED-s?

As an athlete or active individual it is important to fuel properly for the training and exercise that you undertake. Ensure that your energy intake is adequate, and that a large portion of energy intake is coming from carbohydrates which are the main fuel used for exercise. Nutrition both before and after your training sessions should be prioritised to ensure you are properly fuelling and recovering. Be aware that your nutrition will need to increase if your training load increases, and do not follow restrictive dieting practices if you are exercising at a moderate to high intensity. Cutting out food groups unnecessarily can be detrimental as we need a range of nutrients in our diet to maintain health. In particular dairy foods and certain dietary fats provide calcium and vitamin D which are essential to maintain healthy bones and avoid fractures. Apart from nutrition, stress and sleep are also key factors that can influence energy availability, try to minimise stress and prioritise sleep where possible.

If any of the signs and symptoms are ringing alarm bells for you, don't hesitate to get in touch and work with an Athletic Eating sports nutrition professional to help you optimise your energy intke for health and perfroamnce. Service information via the Serices tab on this website!



Mountjoy, M., Sundgot-Borgen, J., Burke, L., Ackerman, K. E., Blauwet, C., Constantini, N., . . . Budgett, R. (2018). International Olympic Committee (IOC) Consensus statement on relative energy deficiency in sport (red-s): 2018 update. International journal of sport nutrition and exercise metabolism, 28(4), 316-331. doi:10.1123/ijsnem.2018-0136