What is Relative Energy Deficiency Syndrome (RED-S)?

July 16, 2025

What is Relative Energy Deficiency Syndrome?

Relative Energy Deficiency Syndrome (RED-S) occurs when athletes consume insufficient calories to meet the energy demands of their training and daily activities. This condition can affect athletes of all genders and levels, leading to impaired physiological functions, including metabolic rate, menstrual function, bone health, immunity, and cardiovascular health. 

RED-S is primarily caused by low energy availability (LEA), where the energy intake is inadequate to support the energy expenditure required for health and performance. This can be intentional, due to restrictive eating habits, or unintentional, due to a lack of awareness about nutritional needs (check out this blog on nutrition and hydration from our Dietitian to learn more about this space). LEA leads to the body prioritizing essential functions, resulting in compromised health and performance.

Common Symptoms

Athletes with RED-S may experience a range of symptoms, including:

• Fatigue and decreased endurance
• Unexplained weight loss
• Menstrual dysfunction in females (e.g., amenorrhea)
• Decreased bone density, leading to stress fractures
• Increased susceptibility to infections
• Mood disturbances, such as anxiety and depression.

Nutritional Assessment

A comprehensive nutritional assessment is crucial for diagnosing and managing RED-S. This assessment with our in-house Dietitian typically includes:

• Dietary Evaluation: Analyzing the athlete's food intake to ensure they are consuming sufficient calories, macronutrients (carbohydrates, proteins, fats), and micronutrients (vitamins and minerals) to meet their energy needs.
• Anthropometry and Body Composition Analysis: Measuring body weight, body mass index (BMI), and body composition (e.g., muscle mass, fat percentage) to assess nutritional status and identify any imbalances.
• Biochemical Testing: Conducting blood tests to check for deficiencies in vitamins, minerals, and hormones that can affect energy availability and overall health.
• Clinical Examination: Evaluating physical signs of malnutrition or overtraining, such as muscle wasting, poor skin condition, and fatigue.
• Patient History: Reviewing the athlete's medical history, training regimen, and lifestyle factors that may contribute to RED-S.
  
  

Rehabilitation: From Acute to End Stage

Rehabilitation for RED-S involves a multidisciplinary approach between a Dietitian, a Sports Physician/ GP and Physiotherapist, progressing through different stages:

Initial Stage

• Nutritional Assessment and Intervention: Immediate focus on increasing energy intake to meet the body's needs. This may involve working with a sports dietitian to develop a balanced meal plan.
• Rest and Recovery: Reducing training intensity and volume to allow the body to recover. This is a plan created by the Sports Physician and Physiotherapy together with the athlete, and it usually requires a strict reducing and reintroducing phases (which are measured very specifically).

Mid Stage

• Medical Evaluation: Further testing by a sports doctor to assess nutritional status, including blood tests for vitamins, minerals, and hormone levels may occur to make sure we are headed away from LEA levels.
• Reintroduction of more output: Gradual re-introduction of training exercises to rebuild muscle mass and bone density is led by the Physiotherapist. Activities like resistance training and weight-bearing exercises are beneficial, especially for bone loading goals, but cardiovascular retraining, sports-specific skill training, flexibility and coordination is vital as well.

End Stage

• Return to Sport: Gradual reintroduction to sport-specific drills and full activity is implemented, if the athlete is showing great improvements in their RED-S signa and symptoms. This overall plan can be happening across weeks to months, but your trusty OHL Physio and Dietitian team will have your back throughout!
  
  

Summary

Relative Energy Deficiency Syndrome is a serious condition that requires a comprehensive rehabilitation plan involving nutritional intervention, medical evaluation, and structured training led by an experienced Physiotherapist. By addressing the underlying causes and following a phased rehabilitation approach, athletes can recover effectively and return to their sport with reduced risk of re-injury. If you suspect you have RED-S, consult your OHL physiotherapist ASAP (and/or you can start with a local sports doctor) to develop a personalized rehabilitation program tailored to your needs. Call us today on 9431 5955 or you can book online anytime via our website.

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