What is REDs?

Written By Gabriella Childers

Relative Energy Deficiency in Sport…

Aka “REDs”, occurs when an athlete isn’t eating enough to meet the energy demands of their training. Underfueling over time can lead to a variety of symptoms that begin to impair performance and recovery. REDs can affect any athlete, regardless of sport, gender, or level of experience.

We often see REDs in athletes with poor body image, food allergies or sensitivities, restrictive diets, low appetite, or simply a lack of awareness about their energy needs. Whether intentional or not, underfueling is common and can have serious consequences.

What Causes REDs?

Relative Energy Deficiency in Sport (REDs) develops when, over time, an athlete’s energy intake does not meet the demands of their energy expenditure. Ideally, athletes consume enough energy to meet their total daily energy expenditure (TDEE) — the total amount of energy the body uses each day.

TDEE includes:

  • Exercise Activity Thermogenesis (EAT):

    Energy used for structured exercise, training, and competition.

  • Non-Exercise Activity Thermogenesis (NEAT):

    Energy used for daily movement outside of formal exercise, such as walking, standing, fidgeting, and household tasks.

  • Thermic Effect of Food (TEF):
    Energy required to digest, absorb, and metabolize food.

  • Basal Metabolic Rate (BMR):
    Energy required to keep your body functioning at rest, including organ function and basic physiological processes.

When athletes consistently fail to meet their TDEE, a cascade of physical, mental, and physiological consequences can occur, ultimately impairing both health and performance.

Many athletes underestimate how much energy they truly need — especially those with a history of restrictive eating, suppressed hunger cues, or rigid food rules. In these situations, the risk of REDs is significantly higher. Learning how to properly fuel training, recovery, and daily life is essential for supporting long-term health, performance, and resilience.

Symptoms of REDs:

Physical Signs:

  • Unexplained fatigue and low energy

  • Weight loss

  • Frequent illness

  • Recurrent injuries

  • Decreased sport performance

  • Decreased response to training stimulus

  • Low libido or change in menstrual function

  • Disruptions to puberty 

  • Difficulty maintaining warm body temperature

  • Iron deficiency

Psychological signs:

  • Depression

  • Increased irritability 

  • Decreased concentration 

  • Decreased Coordination

  • Impaired judgment

  • Desire to skip rest days

  • Drive for thinness

  • Avoidance of meals or food groups

  • Feeling the need to “earn one’s food”

  • Body dysmorphia

Only doctors can diagnose REDs, but sports dietitians play a critical role in treatment and recovery.

How does REDs impair performance?

If left untreated, REDs can impact multiple systems in the body, including:

  • Reproductive health

  • Bone health

  • Immunity

  • Metabolism

  • Heart health

  • Mental health

For athletes experiencing REDs, this can translate into real, tangible risks:

  • Injuries: Higher likelihood of stress fractures, soft tissue injuries, and early-onset osteoporosis

  • Illness: More frequent infections or colds due to decreased immunity

  • Mental health challenges: Mood changes, anxiety, depression, and a higher risk of disordered eating

  • Digestive issues: Gas, bloating, constipation, and other GI discomfort

  • Heart concerns: Low heart rate, dizziness, and potential long-term cardiovascular effects

  • Nutrient deficiencies: Low iron or insufficient overall calorie intake

Just because these symptoms are common among athletes does not mean they are normal. REDs is a serious, yet often overlooked, condition — and it’s preventable with proper fueling and support.

Treating REDs

The good news? REDs is treatable! You are not stuck. With adequate nutrition, proper guidance, and individualized support, athletes can restore energy balance, improve performance, prevent long-term complications, and return to play better than ever.

If low energy, recurring injuries, or REDs symptoms are holding you back, personalized support from a sports dietitian can help you recover, perform better, and break through performance plateaus.

Ready to break barriers? Personalized 1:1 Nutrition Coaching is for you!

Gabriella Childers