Relative energy deficiency in sport (RED-S) can occur when athletes use more energy than they take in. This may happen because they have consumed too few calories or exercised too much.

Symptoms of RED-S can differ greatly among individuals. A person with RED-S may work with their doctors, nutritionists, and psychologists to help manage symptoms and treat the condition.

Read on to learn more about RED-S. This article looks at symptoms, causes, treatments, diagnosis, and more.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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If athletes do not consume enough calories, they may not have enough energy to support their exercise. For example, accidentally skipping breakfast before a game may cause a temporary energy deficit.

In the long term, not getting enough energy can lead to RED-S.

Individuals with RED-S do not have enough energy to support their body’s usual functions. This low availability of energy can cause:

  • irregular or missed periods
  • hormonal changes
  • immune problems
  • gastrointestinal issues
  • impaired growth and development

Competitive athletes are at risk of developing RED-S. It can also affect recreational athletes. Anyone who exercises regularly may develop RED-S if they do not consume enough calories to fuel their workouts.

The symptoms of RED-S can vary widely between individuals. In female athletes, a common symptom of RED-S is missed periods. It can also cause low bone mineral density.

Among male athletes, delayed puberty or stunted growth may indicate RED-S. It can also affect bone health and reproductive function.

Other common symptoms of this condition include:

  • tiredness
  • unexplained weight loss
  • sleep disturbances
  • difficulty concentrating
  • reduced heart rate
  • anxiety
  • depression
  • stomach issues

Individuals with RED-S may find it difficult to have energy for day-to-day activities. They may also be more susceptible to injuries. Over time, they may experience mental health issues.

When athletes do not eat enough food to fuel their activity level, RED-S may develop.

For example, athletes preparing for an upcoming competition may engage in intense exercise. They may unintentionally eat too few calories to make up for this extra physical activity.

Some sports also have weight requirements. Athletes may undereat in order to qualify for a certain weight class. This can also lead to RED-S.

In many cases, RED-S occurs as a result of disordered eating. Sports that emphasize thinness can trigger disordered eating patterns among athletes. These sports may include:

  • gymnastics
  • wrestling
  • running
  • synchronized swimming
  • cycling

One research review noted that about 44.8% of female gymnasts did not eat enough food to meet their energy needs. Athletes in weight-focused sports can be at an especially high risk of RED-S.

Athletes may also develop RED-S as a result of high pressure to perform well. This is because pressure to perform at a high level can trigger restrictive eating, excessive exercise, or both.

Recreational athletes and gym-goers may also develop RED-S. This may occur among individuals focused on achieving a particular weight. It may also happen when people simply underestimate their calorie needs after starting a new fitness program.

Doctors may diagnose RED-S after determining that an individual meets the diagnostic criteria. They may provide athletes with questionnaires about their eating and exercise habits. Athletes who achieve certain scores may qualify for a RED-S diagnosis.

However, self-reporting alone may not be sufficient for a RED-S diagnosis. In addition to screening tools like questionnaires, doctors may look for physical signs of RED-S. This condition can affect:

  • bone health
  • menstrual and reproductive health
  • metabolism
  • the endocrine system
  • mental health
  • growth patterns
  • the immune system
  • the heart
  • the gastrointestinal system

A doctor can examine physical symptoms during a routine examination. If they notice physical signs like those listed above, they may conduct a full diagnostic exam for RED-S.

Treatments for RED-S typically involve working with doctors, nutritionists, and psychologists. A doctor can help monitor energy levels and recommend calorie goals. They may also recommend working with a nutritionist to come up with a personalized diet plan.

A psychologist can help people with RED-S who may be experiencing disordered eating. Working with a therapist can help improve mood and speed up the recovery process.

Individuals with RED-S may experience negative effects on their athletic performance. These may include:

  • higher risk of injury
  • reduced concentration
  • lack of response to training
  • reduced strength
  • decreased endurance

Athletes with RED-S may find it harder to perform during training sessions and games. They may also find it harder to recover from their workouts, which can lead to added muscle soreness.

Over time, RED-S can also cause cardiovascular issues. Individuals with RED-S may develop thyroid problems, iron deficiency, and appetite loss. These and other symptoms of RED-S can have a negative effect on athletic performance.

In some cases, it may be possible to prevent RED-S. It is best for individuals who exercise regularly to contact a doctor or nutritionist to learn more about the nutrients their bodies need. A medical professional can help recommend a diet plan specific to each individual.

Eating enough calories to fuel exercise can help prevent RED-S. It is also important for athletes to focus on eating the right nutrients at the right times.

Getting the appropriate balance of carbohydrates, proteins, and fats is a crucial part of an active lifestyle. Eating before and after exercise helps the body prepare for and recover from a tough workout.

Finally, having the right support can also help athletes avoid RED-S. Consider avoiding coaches who focus on achieving a low weight. Instead, look for coaches and trainers who make overall health their top priority.

Individuals who do not consume enough calories to fuel their workouts may develop RED-S.

Competitive athletes in certain sports may have a particularly high risk of RED-S. However, anyone who exercises regularly can develop this condition.

The immediate side effects of RED-S can include fatigue, weight loss, and missed periods. RED-S can also lead to long-term health effects like bone weakness or cardiovascular issues.

It is best for anyone showing signs of RED-S to contact a medical professional. A doctor can help develop an eating plan that supports each individual’s activity level.