Blog Post

What RED-S is and How to Manage It

Relative Energy Deficiency in Sport title

What is RED-S

Relative Energy Deficiency in Sport, “RED-S” or simply “RED-S” is a clinically defined syndrome referring to the impairment of physiological function caused by a deficit in a person’s energy intake relative to the energy required to maintain optimal health, homeostasis, growth, the activities of daily living, and sport. 

Being in this state of relative deficit is often also referred to as being in a state of low energy availability (LEA). In this state, there is a lower amount of energy than required for the body’s normal physiological functions.

This can have a variety of health consequences including: 

The International Olympic Committee (IOC) has developed two RED-S models. This first one shows 10 health consequences linked to RED-S:

RED-S consequences

Traditionally these negative health effects were mainly considered to be a problem in women. The concept of RED-S has been adapted and expanded from a previously identified syndrome, known as the Female Athlete Triad. 

The female athlete triad is a medical condition defined as ‘the combination of disordered eating (DE) and irregular menstrual cycles eventually leading to a decrease in endogenous oestrogen and other hormones, resulting in low bone mineral density‘.

the female triad

More recently the consequences beyond menstrual dysfunction and poor bone health, as well as the fact that that these problems may also be present in males, has led to the more encompassing term of ‘RED-S’ being used to refer to this syndrome. 

Who is at risk?

Active men or women with disordered eating or with an eating disorder are at risk.

Disordered eating (DE) is a term that refers to a range of irregular eating behaviours but does not fit the full criteria to be diagnosed as a specific eating disorder.  

The DE continuum can lead to clinical eating disorders (EDs), abnormal eating behaviours, distorted body image, weight fluctuations, medical complications and variable athletic performance. 

DE can include (but isn’t limited to) things like: 

  • Chronic restrictive eating
  • Excessive fasting
  • Food-related anxiety 
  • Skipping meals
  • Restricting entire food groups
  • Negative preoccupation with food
  • Negative preoccupation with weight and body image
  • Misuse of laxatives or diuretics

Eating disorders (ie anorexia nervosa, bulimia nervosa, binge eating disorder, and others) are diagnosed according to specific and narrow criteria. The criteria can be found in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM).

Elite athletes are also at risk. 

Up to 70% of elite athletes competing in weight class or aesthetic sports (both male and female) are dieting with the intention of reducing weight before competition. 

From an energy balance standpoint, weight loss is only possible when you are in a calorie deficit, i.e. consuming fewer calories than you are using. 

On top of this, some type of disordered eating pattern often accompanies this weight loss attempt.

Other times, mismanaged programming for rapid reductions in body mass/fat, or inability to track and match calorie intake with extreme exercise commitments contributes to an energy imbalance.

Younger athletes and teenagers are also a high-risk category. In addition to the energy demands of their sport, they also have higher energy requirements to support growth and physical development throughout maturation. 


Similarly to The International Olympic Committee’s 10 health consequences linked to RED-S, they have also developed the 10 main performances consequences linked to RED-S.

REDS performance consequences

The body is a complex working system. When one area is affected by low energy availability it can have downstream consequences in many areas. 

Metabolic rate is downregulated as the body attempts to conserve energy.

The endocrine system is disrupted with energy being diverted away from the reproductive axis. 

Hormones such as estrogen and testosterone can become deficient leading to concerns for fertility, bone mineral density, and hypogonadism. 

Low bone mineral density comes with increased fracture risk and increased osteoporosis risk later in life. 

Dislipidemia and increased LDL cholesterol levels have negative effects on the cardiovascular system. 

Signs & Symptoms

Indications that you might be suffering from RED-S are highly individual but can include:

Low body mass/low body fat, weight loss, lack of normal growth and development, menstrual dysfunction, recurrent injuries and illnesses, decreased performance, mood changes.

There are various screening tools available for health professionals to assist in evaluating individuals at risk of, or with suspected RED-S such as the RED-S CAT


Early detection is important in the diagnosis of RED-S, and a high level of caution is warranted in physique, weight class, lean body, and endurance sports.

Energy Availability

LEA plays a crucial role in the development of the RED-S. The presence and causes of the LEA should be a target when aiming to prevent/treat RED-S. However:

There are currently no standardised guidelines to determine Energy Availability (EA).

insta post EA1

To estimate Energy Intake (EI) tools such as a food diary, food recall and calorie counting can be used.

To measure exercise energy expenditure (EEE) exercise logs, GPS, HR sensors, and pedometers can be used. 

FFM can be quantified by methods such as dual-energy X-ray absorptiometry (DXA) and anthropometry

Measurement and interpretation of each of these components requires expertise and is generally imprecise, and should be considered contextually with each athlete. 

Treatment strategies of RED-S

The treatment of LEA should involve an increase in EI – that is, eating more calories. Increasing energy availability can also be achieved by a reduction in exercise. A combination of both is likely the best strategy. 

There have been some small intervention studies showing success in treating RED-s by introducing an energy-rich supplement (ie a shake or a liquid meal) in combination with a small reduction in training, or the introduction of an additional rest day. 

It should be noted that this strategy may fail to address some of the other factors that can contribute to RED-S such as underlying psychological elements, or poor overall dietary practices.

A practical treatment approach to address low EA incorporates all these treatment modalities.

For example, adding ∼300–600 kcal/day to current intake can help address poor dietary practices such as fueling around exercise sessions and diet composition. If underlying psychological issues are a concern these should be addressed by the relevant health practitioners. 

Vitamin D and calcium play critical roles in laying down bone tissue. These supplements may also be useful in the context of sufferers of RED-S.  

Building on The IOC consensus statement: beyond the Female Athlete Triad—Relative Energy Deficiency in Sport (RED-S), it is recommended that affected athletes should include 1500 mg/day of calcium.

This can be done through dietary sources if possible, but supplementation may otherwise be required.

insta post calcium

The Endocrine Society Guideline recommends maintaining vitamin D [25(OH)D] blood levels above 32–50 ng/mL, with 1500–2000 IU/day of vitamin D.

Vitamin D deficiency is common in the general population and can be even more of a concern in athletes, especially if the majority of their training is done indoors, or during winter when there are fewer hours of sunlight.

Differing Caloric Needs

There is no consensus regarding the cut‐off for optimal EA in athletes. 

For example, to lose weight female athletes are recommended to follow a diet and exercise programs where EA is between 30 to 45 kcal/kg FFM/day.

Below are some of the values that are most commonly cited in the existing literature for calculating the energy requirements of athletes.

insta EA3

The awareness of RED-S has been improving in recent years and awareness continues to grow. Early recognition of signs and symptoms is critical for the early detection and treatment of this health and performance threatening syndrome. As with many aspects of health and performance, good dietary management is a key factor in preventing and treating RED-S.

By Tyler Brooks

Tyler has a Bachelor of Nutrition and Exercise Sciences and completed his Masters of Dietetics through the University of Queensland after moving away from a long career in the fitness industry. As part of his education he worked with dietitians at the Brisbane Broncos rugby league club, is currently working with the Qld Women's Rugby 7's team, and has continued to follow his passion for performance nutrition. Tyler is a believer in 'practice what you preach'. Outside of helping people achieve their goals through diet and exercise, he competes in powerlifting and loves experimenting with his own nutrition and diet to find the best ways to support various training and body composition goals.