Relative energy deficiency in sport (REDs) is a condition that develops when an athlete doesn’t get enough fuel to support their body’s energy demands.

Relative energy deficiency in sport (REDs) can affect athletes at every level, from recreational event competitors to Olympic medalists. If left unrecognized and untreated, REDs may drastically affect long-term athletic performance and overall quality of life.

When your body doesn’t get enough fuel from food, it gradually adapts by reducing functions that are not essential but have a high energy cost, such as hair growth and digestion.

REDs may lead to health challenges such as:

  • hormonal changes
  • low immunity to viruses and bacteria
  • gastrointestinal problems
  • mental health conditions
  • cardiovascular disorders

An athlete may develop REDs if they consistently do not consume enough calories to support their body’s energy demands.

Low calorie intake (consuming fewer calories than your body needs) over a period of time leads to low energy availability.

During periods of low energy availability, your body must prioritize certain functions over others. It typically prioritizes functions that are essential for life, such as breathing, heart function, and brain function.

Many nonessential but high energy functions may slow down, which can lead to health complications.

Examples of nonessential functions with a high energy demand include:

  • growth
  • some hormone production
  • new bone formation and repair
  • menstrual periods

The term “REDs” was introduced in an International Olympic Committee consensus statement in 2014 to expand on an existing condition called “the female athlete triad.” The change was made to emphasize that REDs can affect anyone, even if it is more common in female athletes.

The female athlete triad involves three conditions that often occur together:

Sports in which REDs is common

REDs can affect any athlete who isn’t getting enough energy through food, but it’s particularly common in:

  • endurance sports, such as:
    • cycling
    • rowing
    • distance running
  • sports that emphasize thinness or leanness, such as:
    • figure skating
    • gymnastics
    • diving
    • bodybuilding
  • sports with weight categories, such as:
    • weightlifting
    • wrestling
    • boxing

The prevalence of low energy availability in female athletes has been reported to be as high as 44.8% in gymnasts and 33.3% in soccer players.

REDs and overtraining syndrome

Overtraining syndrome can occur if you perform more physical activity within a certain time period than your body can recover from. It’s characterized by hormonal changes that can lead to many of the same symptoms as REDs, including:

  • intense fatigue
  • increased injury risk
  • reduced athletic performance

According to a 2023 consensus statement from the International Olympic Committee, REDs and overtraining syndrome usually have overlapping symptoms, and healthcare professionals can’t use any single biomarker to diagnose either condition.

REDs develops when an athlete burns more calories than they take in over a period of time. This gradual energy imbalance may be accidental or intentional.

Some athletes, such as those competing in endurance sports, have energy demands that greatly exceed the needs of nonathletes. Undereating may be common among these athletes for many reasons, such as lack of appetite or challenges with meal planning.

Some psychological factors can also contribute to undereating. In some sports, such as those that emphasize weight or leanness, athletes may undereat to maintain a specific body shape and size that is required for competition. For other sports, the primary motivation may be to improve the strength-to-bodyweight ratio and performance.

Athletes at high risk of REDs

Athletes at risk of REDs may include those who:

  • are competitive or professional athletes
  • participate in sports that emphasize leanness or require a certain weight
  • are focused on maintaining a certain body image
  • exercise excessively
  • have depression
  • feel pressure to perform at a high level

REDs can cause many symptoms that affect multiple organ systems, including:

  • fatigue
  • weight loss
  • missed or irregular periods
  • hormonal problems
  • digestive problems
  • bone density loss
  • stress fractures
  • repeated muscle or connective tissue injuries
  • cold intolerance
  • low sex drive
  • frequent illness
  • slow heart rate
  • low blood pressure
  • decreased athletic performance
  • hair loss
  • cognitive changes such as

Preventing REDs starts with educating athletes and yourself about the potential harms of not consuming enough energy for a specific activity. It may also involve developing a plan to ensure adequate nutrition.

Educational programs should focus on increasing nutritional knowledge and recognizing disordered eating patterns.

You can help prevent REDs by:

  • eating a nutrient-dense diet that includes enough fat, carbohydrates, and protein intake at every meal
  • ensuring that you match the amount of food you eat to your exercise and activity level
  • scheduling adequate rest periods into your training

A team of performance experts can potentially help you prevent REDs and improve your energy balance. You may benefit from working with experts such as:

  • sports sciences and physiologists
  • nutrition experts
  • sports psychologists
  • sports medicine doctors
  • sports-specific coaches

Mild REDs may be treatable with dietary changes alone. However, athletes with prolonged or severe low energy availability or underlying eating disorders might need to take time off from training and get support from a mental health professional.

REDs is a condition that develops when an athlete’s energy intake is too low to meet their energy requirements. It can lead to health challenges such as frequent infections, depression, and intense fatigue.

The primary treatment for REDs is increasing calorie intake to meet energy demands. However, this may be difficult to do if the deficit is significant. By working with sports performance experts, you can help prevent REDs and maximize your performance.