Relative Energy Deficiency in Sport — RED-S Syndrome

It was previously thought that the negative health effects caused by consuming an inadequate amount of energy applied only to female athletes. Known as the Female Athlete Triad, this explained the relationship between poor energy availability, bone mineral density, and menstrual function.

However, this has since seen an update and we now know that this issue may be more common in the female athlete but is also present in the male athlete. This inclusion led to the renaming of the Female Athlete Triad to Relative Energy Deficiency in Sport (RED-S), and no, you do not need to be an elite athlete for this to affect you.

What is RED-S?
If your energy intake compared to your training demand is consistently out of balance, both acutely (e.g. to make racing weight) or chronically, you may not have enough energy to cover the cost of your training, daily living and metabolic demands. This energy deficiency can then impact your metabolic rate, bone health, fertility (both men and women), immune function, and also the wellbeing of your heart and mental health.

Impact on Performance:
Performance is also going to be negatively affected by RED-S. The main reason for this is that being in an energy deficit can reduce your adaptations to training, while also declining endurance capacity, strength and speed. It is likely that not meeting energy requirements will also slow recovery, which is a real issue when considering the training load of all levels of triathletes and frequent double training days.

Social Media: Mixed messages about performance nutrition online means many confusing diets are at your finger tips.
No energy: Keep RED-S SYNDROME at bay with a controlled nutrition plan.


What is considered as Inadequate Energy Intake?
To calculate energy adequacy, you need some key pieces of data. A sports physician or sports dietitian can help with this. The calculation for energy availability (EA) is your total energy intake (EI) minus your total energy expenditure (TEE), which is then divided by your fat free mass (FFM). If this comes out at less than 30kcal/kg FFM/day, it is likely this will be having the affects seen in RED-S.

Who is at Risk?
Not just an elite issue!
Not matching energy intake with daily energy needs is not just an issue facing lean athletes. Low body fat can be a risk factor but in and of itself, it is not a diagnosis. All athletes are at risk of the side effects of inadequate energy intake and we often find that it can lead to difficulties losing weight, too, due to a suppressed metabolism (metabolic rate).

Disordered Eating
Disordered eating practices are one of the major risk factors. We find that athletes can frequently move between habits of restriction into clinical eating disorders. The risk can run in your family or be sports specific. Triathletes can be at risk due to frequent overtraining, going in and out of injury/rehab and aiming to make weight to improve performance.

Social and Social Media Pressures
The other real worry in this area is the explosion of social media wellness warriors and overall healthy eating pressures. The rapid growth in social media, and the subsequent mixed messages about performance nutrition have given voice to many restrictive and confusing ‘diets’ that are all touted as the best option. These external pressures can lead to disordered eating behaviours that may start well-intentioned, however grow into restriction and obsession over time – called Orthorexia. In fact, over 20 per cent of athletes have been shown to have signs of disordered eating.

Accidental Imbalance
It is also important to highlight that poor energy availability doesn’t just happen due to a diagnosed eating disorder or disordered eating. While this can be a calling card, an imbalance between food intake and training demands can happen to any of us. For the majority reading this, it is likely accidental due to the time constraints that come with trying to balance training with work, family and life commitments. These challenges can prevent us from having the time to consider our requirements each day and adapting intake to match higher training demands. For example, if you are one to eat the same thing every day, without considering the changes to your training load, you may be at risk of becoming chronically energy deficient over time. An example of this is male heavyweight rowers. Male heavyweight rowers have such high training loads and energy needs, they have been found to be at high risk of RED-S – despite being male and of a
high body weight.

Alarm bells: Consult with a sports dietitian if you think you have symptoms.


Signs and Symptoms
How can RED-S present itself and what can you be looking out for in terms of symptoms? These can vary widely – you may have all of them or you may have some of them. Take into account your current training load and your intake, and if in doubt seek a sports dietitian for a full analysis.


  • Disordered eating patterns that may include overly restricting intake or food groups, skipping meals or using unsafe weight loss methods; and/or
  • Poor bone health with a below normal Bone Mineral Density (BMD); and/or
  • Depressed mood or irritability; and/or
  • Susceptibility to ongoing illness (poor immune function); and/or
  • Reduced performance, recovery and adaptations to training


  • Symptoms of Low Energy Availability can be a little less obvious in guys than girls; however, this does not make the health impact less serious.
  • Disordered eating patterns that may include overly restricting intake or food groups, skipping meals or using unsafe weight loss methods; and/or
  • Poor bone health (stress fractures can often be a sign of this) with a below normal Bone Mineral Density (BMD); and/or
  • Reduced sex drive/Lower sex hormone levels/Issues with fertility; and/or
  • Depressed mood or irritability; and/or
  • Susceptibility to ongoing illness (poor immune function); and/or
  • Reduced performance, recovery and adaptations to training

Let’s put this into Practice
Let’s use a 35-year-young male long-course triathlete weighing 70kg, with a FFM of 63kg (10% body fat). He comes to see us with low energy levels, stagnant performance and poor recovery. It is approaching the tri season and he is sick frequently.
Averaging his exercise expenditure over the week, we get an average daily cost of 1000 kcal (4200 kJ). After going through his weekly food diary, he is averaging a consumption of 2800 kcal (11 700 kJ)
per day.
Using the above calculation tools, this would look like:

EA = (2800 kcal – 1000 kcal)/63kg = 28.6 kcal/kg of FFM/day

With EA coming in under 30 kcal per day, it is likely that the symptoms this athlete is feeling are due to the effects of inadequate energy availability.

What Next?
If these symptoms ring true to you, it should set off some alarm bells for caution. It is important to consider a follow-up with a sports medicine physician for assessment and appropriate treatment strategy. From there, management will include discussions with a sports dietitian and may also involve an exercise physiologist and/or sports psychologist as needed. Treatment will focus on correcting your energy balance while also creating a long-term environment that encourages a healthy, balanced relationship with food and nutrition.



Mountjoy M, Sundgot-Borgen J, Burke L, Carter S, Constantini N, Lebrun C, Meyer N, Sherman R, Steffen K, Budgett R, Ljungquvist A. The IOC concensus statement: beyond the Female Athlete Triad – Relative Energy Deficiency in Sport (RED-S). Br J Sports Med 2014;48:491-497. doi:10.1136/bjsports-2014-093502.

Loucks AB. Energy balance and body composition in sports and exercise. J Sports Sci 2004;22:1-14.

Sundgot-Borgen J, Meyer NL, Lohman TG, et al. How to minimise the health risks to athletes who compete in weight-sensitive sports: review and position statement on behalf of the Ad Hoc Research Working Group on Body Composition, Health and Performance. Br J Sports Med 2013;47:1012-22.

Sundgot-Borgen J, Torstveit MK. Aspects of disordered eating continuum in elite high-intensity sports. Scand J Med Sci Sports 2010;20(Suppl 2):112-21.

Matinsen M, Sundgot-Borgen J. Higher prevalence of eating disorders among adolescent elite athletes than controls. Med Sci Sports Exerc 2013;45:1188-97.

Mountjoy M, et al. Author’s 2015 additions to the IOC consensus statement: Relative Energy Deficiency in Sport (RED-S). Br J Sports Med April 2015;49.

Filaire E, Rouveix M, Pannafieux C, et al. Eating attitudes, perfectionism and body-esteem of elite male judoists and cyclists. J Sports Sci Med 2007;6:50-7.

Baum A. Eating disorders in the male athlete. Sports Med 2006;36:1-6.

Vogt S, Heinrich L, Schumacher YO, et al. Energy intake and energy expenditure of elite cyclists during preseason training. Int J Sports Med 2005;26:701-6.

Ferrand C, Brunet E. Perfectionism and risk for disordered eating among young French male cyclists of high performance. Persept Mot Skills 2004;99:959-67.

Nattiv A, Loucks AB, Manore MM, et al. American College of Sports Medicine position stand: The Female Athlete Triad. Med Sci Sports Exerc 2007;39:1867-82.

Mountjoy M, et al. The IOC Relative Energy Deficiency in Sport Clinical Assessment Tool (RED-S CAT). Br J Sports Med 2015;0:1-3.

Arends JC, Cheung MY, Barrack MT, et al. Restoration of menses with nonpharmacologic therapy in college athletes with menstrual disturbances: a 5 year retrospective study. Int J Sport Nutr Exerc Metab 2012;22:98-108.

Loucks AB, Thuma JR. Lutenizing hormone pulsatility is disrupted at a threshold of energy availability in regularly menstruating women. J Clin Endocrinol Metab 2003;88:297-311.

Ackerman KE, Misra M. Bone Health and the Female Athlete Triad in Adolescent Athletes. Phys Sports Med 2011;39:131-41.


Alicia Edge

Alicia is an Advanced Sports Dietitian with an online sports nutrition business, Compeat Nutrition. She is also a mum and triathlete, so advice extends beyond the basics and is instead focused on providing effective and achievable nutrition for both training and racing.

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