10 Warning Signs of RED-S (Relative Energy Deficiency in Sport) Every Athlete Should Know
If you suspect you have RED-S and need to consult a Sports Dietitian, schedule a FREE 15-minute discovery call with me to discuss your situation.
What is RED-S?
Relative Energy Deficiency in Sport, or RED-S, is a condition that happens when an athlete’s energy (calorie) intake is insufficient to meet the needs of living and overall physiological needs. This energy deficit impacts various bodily systems, leading to different physical, psychological, and performance-related issues. RED-S is not solely about a lack of calories but rather an imbalance between energy intake and the energy expended by the body.
Athletes may experience this due to restrictive dieting, intense training regimens, or a combination of both. In response to this, the body suppresses functions that are not essential for survival, such as reproductive hormones, and bone maintenance. RED-S can happen to athletes of all levels, from amateur to elite. Sometimes, RED-S can happen without the athlete’s knowledge, or
Understanding and recognizing the signs of RED-S is important for athletes, coaches, and healthcare professionals. Early detection can prevent long-term health consequences and maintain both athletic performance and overall well-being.
Here are 10 key warning signs of RED-S to watch out for:
1. Persistent Fatigue and Low Energy Levels
A constant feeling of tiredness or low energy levels, even after sufficient rest, is a common symptom of RED-S. This occurs when the body doesn’t have enough fuel to support its daily functions and recovery needs. Sleep isn’t the only way your body has to recover, but you also need food to replenish glycogen stores, build or maintain muscle, strengthen bones, etc.
2. Irregular Menstrual Cycles
For menstruating athletes, disruptions such as amenorrhea (absence of periods) or oligomenorrhea (infrequent cycles) can suggest hormonal imbalances caused by RED-S. These imbalances can significantly (and sometimes irreversibly) increase the risk of bone loss and other health concerns. Athletes with severe amenorrhea or oligomenorrhea could potentially damage their bones permanently, leading to more injuries, and possibly premature osteoporosis. Delayed menarche (delayed start of first menstrual cycle) in pubescent athletes is a key sign to look out for. Detecting it early on and intervening at that early stage can prevent any future damage.
3. Decreased Bone Density
Low energy availability often leads to reduced bone mineral density, heightening the risk of stress fractures and other bone injuries. This is particularly critical for younger athletes whose bones are still developing.
Decreased bone density is not limited to female athletes. It can happen in any athlete experiencing Low Energy Availability.
Athletes can measure bone density using DXA (Dual-Energy X-Ray Absorptiometry), the gold standard for assessing bone mineral density at the spine, hip, or forearm. Other methods include Quantitative Ultrasound (QUS) for portable, radiation-free screenings, and Quantitative CT (QCT) or MRI for detailed analysis of bone strength and microstructure. DXA is the most precise and widely used, while QUS and MRI are useful for initial screenings or diagnosing stress injuries. Athletes should choose the method based on their needs and risk factors in consultation with their sports physician.
4. Weakened Immune System
Frequent illnesses or infections could signal RED-S. Insufficient energy weakens the immune system, making it harder for the body to fend off viruses and bacteria, which can disrupt training and recovery schedules. If you find that you or your athletes are catching colds and flu more than usual after changing up your training load or eating habits, RED-S could be something to get evaluated for.
5. Digestive Issues
We often tend to blame digestive issues on intolerances, the types of foods we eat, and even stress. Though all of these could trigger digestive issues, RED-S could also. Symptoms such as bloating, constipation, or diarrhea can be linked to RED-S. These issues may arise because the body prioritizes energy for essential functions, leaving the digestive system compromised. In athletes, these symptoms could lead us to falsely believe that we have IBS, considering the symptoms are very IBS-like.
6. Loss of Muscle Mass and Strength
A decline in muscle mass or strength is another warning sign. Inadequate energy intake reduces the body’s ability to build and repair muscle, directly affecting athletic performance.
7. Mental Health Challenges
Psychological effects of RED-S include increased anxiety, depression, and even disordered eating behaviors. Interestingly, emotional dysregulation is also a commonly known hunger queue (think “hangry”). If you’re under-fuelling and in a too-large calorie deficit, it would make sense for your emotions to feel all over the place. These mental health challenges can exacerbate the condition, creating a cycle that’s difficult to break without intervention.
8. Slow Recovery from Injuries and Illness
Athletes with RED-S may find that injuries take longer to heal. The body’s limited energy availability affects its ability to repair tissues and recover effectively from physical stress.
9. Difficulty Concentrating and Focusing
RED-S can impair cognitive functions, such as focus, decision-making, and mental sharpness. This can negatively impact both training and competition performance, especially when you have to make quick decisions or transitions.
10. Sleep Distruptions
Poor sleep quality, trouble falling asleep, or difficulty staying asleep can be linked to RED-S. Sleep disturbances further compound the physical and mental effects of the condition. This creates a cycle keeping athletes stuck in poor recovery and poor performance.
Why Early Detection Matters
Recognizing the signs of RED-S early can save an athlete’s performance (and health). Left untreated, RED-S can lead to severe health issues, including long-term hormonal imbalances, chronic fatigue, and recurring injuries. It can also derail an athlete’s career due to reduced performance.
If you suspect you or your athlete is struggling with disordered eating, give this a read:
Spotting Disordered Eating in Athletes: Red Flags and Risks
What To Do If You Think You Have RED-S
If you or someone you know is experiencing these warning signs, consult a healthcare professional experienced in sports nutrition or medicine. Key steps in managing RED-S include:
Nutritional adjustments: Ensuring adequate energy and nutrient intake from food (not just supplements) to meet training demands with the help of a Registered Dietitian.
Training modifications: Reducing training intensity or frequency to allow for recovery with the help of your trainer or coach.
Mental health support: Addressing disordered eating behaviours and psychological stress with the help of your licensed psychologist.
These professionals can provide the necessary support, guidance, and interventions to address the issue and prevent it from escalating into a more serious condition. Remember, early detection and intervention are key to effectively managing athlete health and eating habits. By being aware of the red flags, sports dietitians can contribute to the well-being and success of athletes both on and off the field.
Final words
By recognizing these 10 warning signs, athletes, coaches, and healthcare professionals can take proactive steps to address RED-S and prevent long-term health and performance consequences. Early intervention, including adjustments to training, nutrition, and mental health support, can be crucial in managing this complex condition.
Contact a Registered Dietitian for a personalized consultation or Complete our consultation form here. With the right support and interventions, you can regain your energy, improve your athletic performance, and protect your long-term health.
If you suspect you have RED-S and need to consult a Sports Dietitian, schedule a FREE 15-minute discovery call with me to discuss your situation and assess whether we are a good fit to work together.
Hope this helped!
Maria Tanielian
Registered Dietitian/Nutritionniste
IOC Diploma in Sports Nutrition
ODNQ # 7223, CDBC # 2815, SDA # 949, CDO #16856
References worth reading with an open mind
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Brook, E., Tenforde, A., Broad, E., Matzkin, E., Yang, H., Collins, J., … & Blauwet, C. (2019). Low energy availability, menstrual dysfunction, and impaired bone health: a survey of elite para athletes. Scandinavian Journal of Medicine and Science in Sports, 29(5), 678-685. https://doi.org/10.1111/sms.13385
Gillbanks, L., Mountjoy, M., & Filbay, S. (2022). Lightweight rowers’ perspectives of living with relative energy deficiency in sport (red-s). Plos One, 17(3), e0265268. https://doi.org/10.1371/journal.pone.0265268
Heikura, I., Uusitalo, A., Stellingwerff, T., Bergland, D., Mero, A., & Burke, L. (2018). Low energy availability is difficult to assess but outcomes have large impact on bone injury rates in elite distance athletes. International Journal of Sport Nutrition and Exercise Metabolism, 28(4), 403-411. https://doi.org/10.1123/ijsnem.2017-0313
Keay, N., Francis, G., Entwistle, I., & Hind, K. (2019). Clinical evaluation of education relating to nutrition and skeletal loading in competitive male road cyclists at risk of relative energy deficiency in sports (red-s): 6-month randomised controlled trial. BMJ Open Sport & Exercise Medicine, 5(1), e000523. https://doi.org/10.1136/bmjsem-2019-000523
Logue, D., Madigan, S., Melin, A., Delahunt, E., Heinen, M., Donnell, S., … & Corish, C. (2020). Low energy availability in athletes 2020: an updated narrative review of prevalence, risk, within-day energy balance, knowledge, and impact on sports performance. Nutrients, 12(3), 835. https://doi.org/10.3390/nu12030835
Mountjoy, M., Sundgot‐Borgen, J., Burke, L., Carter, S., Constantini, N., Lebrun, C., … & Ljungqvist, A. (2014). The ioc consensus statement: beyond the female athlete triad—relative energy deficiency in sport (red-s). British Journal of Sports Medicine, 48(7), 491-497. https://doi.org/10.1136/bjsports-2014-093502
Robertson, S. and Mountjoy, M. (2018). A review of prevention, diagnosis, and treatment of relative energy deficiency in sport in artistic (synchronized) swimming. International Journal of Sport Nutrition and Exercise Metabolism, 28(4), 375-384. https://doi.org/10.1123/ijsnem.2017-0329
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