RED-S: Signs you shouldn't ignore

Feeling constantly tired, struggling to recover after exercise or noticing a decline in your performance? While it's easy to blame a demanding training schedule, these could be signs of Relative Energy Deficiency in Sport (RED-S).

RED-S occurs when your body doesn't have enough energy to support both exercise and essential bodily functions. Although often associated with elite athletes, it can affect anyone who exercises regularly.

Recognising RED-S symptoms early is important for protecting your health, recovery and sporting performance.

What Is RED-S?

Relative Energy Deficiency in Sport (RED-S) is a condition caused by prolonged or severe low energy availability (LEA).

This happens when the energy you consume through food is insufficient to meet your body's needs after accounting for exercise.

Your body requires energy for essential functions, including hormone production, bone health, immune function and muscle recovery. When energy availability is consistently low, these processes can become disrupted.

RED-S can develop through increased training demands, restrictive eating, skipped meals or simply not eating enough to match your activity levels.

Importantly, RED-S can affect athletes of any body weight, even without noticeable weight loss.

Understanding sports nutrition and appropriate fuelling can help you meet your body's energy requirements.

8 RED-S Symptoms You Shouldn't Ignore

RED-S can affect several systems throughout the body, meaning symptoms vary between individuals.

1. Persistent Fatigue

Feeling tired after exercise is normal, but ongoing exhaustion despite adequate sleep and rest may indicate insufficient energy availability. This may cause you to struggle with everyday activities or find your usual training sessions unusually demanding.

2. Declining Sports Performance

If your endurance, strength or training capacity is declining despite consistent training, under-fuelling could be contributing. Inadequate energy and carbohydrate intake can affect muscle recovery, training adaptations and exercise performance.

Our sports nutrition articles explore how nutrition supports training and recovery.

3. Irregular or Missing Periods

Low energy availability can disrupt reproductive hormones, leading to irregular or absent menstrual periods. Although common among athletes experiencing RED-S, menstrual changes shouldn't be considered a normal consequence of intensive training. However, hormonal contraception may also mask these changes, so regular periods aren't the only indicator of adequate fuelling.

4. Frequent Injuries and Stress Fractures

Insufficient energy availability can negatively affect bone health, increasing the risk of bone stress injuries and fractures. If you have persistent bone pain or recurring injuries, it should always be assessed by a healthcare professional.

5. Frequent Illness and Poor Recovery

Low energy availability may impair immune function, making you more susceptible to illness. You might also notice that muscle soreness lasts longer or that you're struggling to recover between training sessions. Having adequate energy and protein intake can support recovery.

6. Changes in Mood and Concentration

RED-S can affect psychological wellbeing, potentially contributing to irritability, low mood, reduced motivation and difficulty concentrating.

Although these symptoms can have several causes, they shouldn't be ignored, particularly alongside other signs of under-fuelling.

7. Feeling Cold More Often

Consistently low energy availability can affect metabolic processes, potentially making you feel colder than usual.

However, feeling unusually cold can also be associated with conditions such as anaemia or thyroid disorders.

8. Hormonal Changes and Reduced Libido

RED-S affects both male and female athletes.

In men, prolonged low energy availability may contribute to reduced testosterone concentrations and changes in libido.

This highlights why RED-S shouldn't be viewed as a condition affecting only female athletes.

Who Is Most at Risk of RED-S?

Although anyone can experience RED-S, certain groups may be more vulnerable, including:

• Endurance athletes: Runners, cyclists and triathletes.

• Aesthetic sports: Gymnastics, dance and figure skating.

• Weight-category sports: Boxing, rowing and martial arts.

• Recreational exercisers: Individuals combining frequent exercise with inadequate food intake.

  
  

Adolescent athletes may also be at increased risk because they require additional energy for growth and development.

If you regularly participate in endurance exercise, understanding how to fuel for a marathon or support triathlon training through nutrition can help you plan your fuelling appropriately.

How Can You Prevent and Recover From RED-S?

Preventing and managing RED-S involves ensuring your body receives enough energy to support exercise and essential physiological functions.

1. Eat Enough to Support Your Training

As training demands increase, your energy requirements generally increase too.

Eating regular meals and snacks can help ensure you're meeting your nutritional needs.

2. Include Enough Carbohydrates

Carbohydrates are an important fuel source for exercise, particularly during moderate- and high-intensity training.

Foods such as bread, pasta, rice, potatoes and fruit can help support energy availability and recovery.

Our guide to carbohydrate loading explains how carbohydrate requirements can change depending on exercise demands.

3. Prioritise Recovery Nutrition

Eating after exercise helps replenish energy stores and supports muscle repair.

Including carbohydrates and protein in your post-exercise meals can support recovery.

For example, Greek yoghurt with fruit and granola, or a chicken or tofu sandwich, can provide both nutrients.

However, meeting your overall daily energy requirements is more important than focusing on one meal or snack.

4. Seek Professional Support

If you're experiencing RED-S symptoms, speak to your GP or a qualified healthcare professional.

A registered sports dietitian can help assess your nutritional intake and develop an individualised fuelling strategy.

Depending on symptom severity, adjustments to training may also be necessary.

The International Olympic Committee's RED-S consensus statement highlights the importance of early identification and appropriate multidisciplinary management.

Frequently Asked Questions About RED-S

Can You Have RED-S Without Losing Weight?

Yes. RED-S can occur at any body weight, even without noticeable weight loss. Someone may maintain a stable weight while experiencing hormonal changes, poor recovery or reduced bone health.

How Long Does RED-S Recovery Take?

Recovery varies depending on the severity and duration of low energy availability. Some symptoms may improve relatively quickly with appropriate nutrition, while hormonal and bone health changes can take several months or longer to recover.

Can Men Experience RED-S?

Yes. RED-S affects both men and women. Male athletes may experience reduced testosterone, fatigue, impaired bone health and declining sporting performance when energy availability remains insufficient.

At Nutrition & Co, our registered dietitians provide personalised nutrition advice to help active individuals fuel their training and support recovery.

If you're concerned about under-fuelling or experiencing potential RED-S symptoms, get in touch with Nutrition & Co to learn how we can help.