There is a disturbing affliction stalking competitive sport these days. It’s insidious in its strength, slowly, silently and steadily eating its way into the very marrow of those who love sport the most. It affects men and women of all ages and of any level in their sport. Most have never even heard of it, and the most worrying of all is that the medical fraternity is still on a steep learning curve with it.

I’ve been researching this article for the past month, and it wasn’t easy finding information that delved deeper than the simple basics available online. Most importantly, I looked for athletes who could relate their experience with the condition, but they were hard to find – not because they’re rare, but simply because most are not comfortable talking openly about their experience.

Relative energy deficiency in sport, or RED-S, is a comparatively recently identified condition. It has been around for decades, but was only introduced as a medical term in 2014, when the International Olympic Committee (IOC) recognised it as a syndrome. It refers to the condition of low energy availability that occurs when a person’s dietary energy intake is not enough to support the energy required for healthy body functioning. Simply put, day after day, week after week, month after month expending more calories than you consume will lead to a state of low energy availability – a physical state of such fatigue that the body no longer has energy to support a healthy metabolism, protein synthesis, bone health, immunity, cardiovascular health, hormonal functioning and, for women, healthy menstrual function.

In addition, RED-S leads to a dramatic decline in sports performance, seeing decreased glycogen stores, lowering of muscle strength, reduced endurance, increased risk of injury, poor response to training, impaired cognitive function, decreased coordination, decreased concentration, mood swings, hormone imbalance and, often, depression.

Sound scary? Well, it’s real, and if we’re not careful, it could happen to any of us. I spoke with Comrades 2018 winner Ann Ashworth, whose gruelling experience suffering RED-S has made her determined to speak out, warning athletes about the condition that almost ruined her running career.


Ann’s story

In September 2016 I decided to pursue my athletic dreams before it was too late. At that time I had run six Comrades and done reasonably well on limited training, and I wanted to know how good I could be if I worked at it. I gave up my job and approached John Hamlett, coach to the 2016 Comrades down run winner and record holder David Gatebe. I knew John was notorious for his hardcore approach to training, and that I needed a dominant and forceful coach to whip me into shape. John put me on an eating plan that was extreme – it severely restricted fat, limited carbs and greatly boosted my protein intake. I was eating a lot of food, but any excess weight dropped off and I soon morphed into a lean, mean racing machine. In 2017 I ran PBs in every distance except Comrades, which I bailed after tearing a muscle on the start line. My results kept improving, and in 2018 I realised my dream by winning the Comrades Marathon.

Looking back now, I realise that my problems started in 2017 as we increased mileage and intensity in preparation for the 2017 Comrades. I began to experience chronic gut distress, which John and I presumed was irritable bowel syndrome (IBS). Some days I felt so tired I could barely get out of bed, but I blamed my heavy training load. I added even more protein to my diet, never carbs or fats. I had repeated muscle strains and tears in the build-up to race day, I saw stars during my training sessions, and was having to dash into the bushes on almost all my runs. But I just thought I had a gluten intolerance and that it was my body trying to adapt to my heavy training load. Significantly, most of these symptoms disappeared after Comrades when my training load was reduced (and I was probably less strict with my diet). I developed my first stress fracture in July 2017 but shortly thereafter went on to win the Legends 68km Ultra in close to record time.

Ann Ashworth in 2019, way underweight at 45kg but before she knew she was suffering RED-S.

When Comrades training kicked off again in December 2017, I looked anorexic but I felt strong. I was eating so much protein that I had no conception that I could be under-fuelling. The more I ran and the harder I trained, the more pronounced my side-effects became. I experienced chronic gut distress despite following a gluten-free diet and cutting out all the foods which typically trigger IBS. I felt exhausted all the time, I ached and, once again, I had recurring injuries. Finally, three weeks before Comrades 2018, I collapsed during a training camp in Dullstroom, prompting me to pack my bags and head home for blood tests. My GP took one look at me and said he was extremely concerned about my health. The blood tests revealed that my body had stopped producing hormones (because without any fat in your body or your diet your system cannot synthesise hormones), that despite all the protein I was eating I was anaemic, and at 45kg I was dangerously underweight (I’m 174cm so that’s pretty lean). A few days later I picked up a stomach bug that had me in bed for a week. Ten days before Comrades race day, in a desperate effort to recover my strength, I loaded up on sugar and carbs like never before (contrary to my strict diet) because I knew I had no reserves for race day. Thankfully, this temporary solution worked and I got through Comrades by eating every 8km, finishing with my win. At that point I still had no idea that I had RED-S.

For the remainder of 2018 I was pretty relaxed with my eating – I ate more carbs than my diet prescribed and I felt good. I trained hard and ran my marathon PB of 2h35 in Valencia, Spain in early December. But come 1st January, I was back on my strict diet and following an even more rigorous training programme than ever. From the outset my performance was doomed. I became weaker and slower, and even began to dread my training sessions. I would do my speedwork on a treadmill so that I could sip energy drinks to keep myself going, and no matter how hard I tried I couldn’t get my weight down to race weight. My legs were sluggish, my head was burnt out and my entire body ached. I cried all the time and was an emotional wreck. Just before Comrades 2019, I was diagnosed with a stress fracture in my spine and I knew my racing was over for the year. But still I lined up on the Comrades start line the following week and ran as hard as I could for as long as I could. In the second half of the race I suffered explosive diarrhoea and for several days was so sore that I couldn’t stand for more than 5 minutes at a time. My body was failing me spectacularly, and I feared I would never run again.

Ann’s story is not unique. Many elite athletes have suffered similar symptoms, not realising that in the pursuit of performance, they had overlooked the fundamental cornerstone of training: adequate and appropriate nutrition. Fuel the engine properly and it will perform. With inadequate fuelling, the engine will eventually splutter to a halt. It’s that simple.

Well, almost…

The key, however, is not only about calories. Ann HAD been taking in calories, but they were not enough of the right calories – her diet was deficient in carbohydrates and fats, the two nutrients essential for endurance running. Instead her diet was protein-heavy. Without carbs and fats, her system was unable to synthesise protein, so she was not only losing body fat but, critically, lean muscle fibre.

Ann’s journey back to health has taken more than a year.

I started working with Christine Rice, a registered dietician who specialises in sports nutrition. She has helped me to fuel according to my body’s needs and to appreciate whole foods and healthy eating again. Within a few weeks of being on a balanced diet my body composition began to improve and I had more energy. After three months I had my first period in three years. Now a year on, everything in my body is finally working properly, my skin is clear, I can concentrate for sustained periods of time and, most importantly, I’m running strong and fast again.

What Ann endured is by no means unusual. While not common, RED-S is suffered by many sports people, and often goes undiagnosed.


Before RED-S

Energy deficiency in sport was previously thought to be a problem only experienced by women, and was termed the female athlete triad. It linked three major symptoms: energy deficiency, the cessation of periods, and a decrease in bone density. Being significantly underweight was another symptom of the female athlete triad. (The irony of the acronym FAT seems to have been lost on the academics studying the condition!)

The renaming of the syndrome to RED-S was a result of research showing the condition was not unique to females, but that in fact male athletes were also affected. Suddenly the world took notice!



It turns out that RED-S affects athletes of any age and gender, and any level of athlete, not only elite. Any presumption that the problem is caused by intentional restriction of calories, effectively an eating disorder, is wrong – while it can be associated with disordered eating, or with the elimination of certain foods to gain a perceived performance edge, there are also those who, for a range of reasons (including limited access to adequate nutrition and food security, as in many parts of Africa), are simply not able to consume enough calories for their energy requirements. Yet again, the condition is complicated.


Diagnosis of RED-S is challenging because the signs can be subtle. When low energy availability becomes sustained, the body tries to protect itself by slowing the metabolism to conserve calories, and by changing the balance of hormones to increase body fat and reduce muscle loss. As Ann experienced, it then becomes increasingly difficult to lose weight or change body composition, which is then usually thought by the athlete to be a result of not training hard enough or taking in too many calories – when in fact the reverse is true. Other systems in the body may also slow or even shut down completely in order to conserve energy.

Common indicators may include:

  • prolonged fatigue
  • muscle loss
  • weight loss (but not always)
  • poor concentration or brain fog
  • amenorrhea / loss of periods (women)
  • aching body
  • recurrent injuries and illnesses
  • stress fractures
  • mood swings
  • depression
  • dizziness
  • gut issues
  • lowered libido

Common performance consequences of RED-S (image credit: International Olympic Committee (IOC) Consensus Statement on Relative Energy Deficiency in Sport (RED-S)


While menstrual disruptions are not necessarily a sign of RED-S or even of over-training, the absence of periods is an indication of a health issue. Many women consider losing their periods nothing but convenient, while some even have the misconception that period loss is a mark of achieving a higher level of fitness. The undisputed fact is that the absence of periods is a sign that there is something wrong, and should be checked.

Prevalence of RED-S

Cape Town based clinical dietitian Rowena Visagie specialises in the treatment of RED-S. As a former South African triathlete, provincial swimmer, cross-country and track athlete, Rowena understands the pressures involved in elite competition and describes the syndrome as nuanced, both in its causes and in the multi-faceted approach required for its treatment.

Rowena says the prevalence of RED-S in South Africa is not yet known, but globally the occurrence of low energy availability, which is the main triggering factor associated with the consequences of RED-S, is estimated to be between 22% and 58% across a variety of sports.

“Any sport or situation where being lean or light is perceived to be important for performance, or where it is part of the culture of that sport, increases an athlete’s risk for developing RED-S. Athletes who have very high training loads, together with unintended inadequate fuelling are also at risk. In our practice we see it most commonly in runners, cyclists, triathletes and aesthetic athletes (eg. dancers, gymnasts and figure skaters). But I’ve also treated rugby players, swimmers, rowers, climbers, hockey players, tennis players, as well as recreational athletes and regular ‘gym-goers’ who have RED-S. It is not clear whether the type of sport influences whether it occurs as a result of intentional or unintentional under-fuelling, although aesthetically-judged, gravitational and weight class sports do seem to increase the risk for the development of disordered eating or eating disorders. Any environment where there is pressure to change body shape, maintain a pre-pubescent body, be lean, or improve power-to-weight ratio puts the athlete at risk, as do more toxic situations such as abusive body shaming.”

Canadian coach, author and consultant in human performance and biomechanics, sports rehabilitation, exercise science and performance training, Chloë Lanthier believes that alongside training, nutrition is the cornerstone of good performance.

“A healthy balanced diet is crucial not only to athletic performance but to our healthy physiological functioning. Just as the quality of the food we eat can have positive consequences on our bodies, if we eat the wrong foods, it can be devastating.”

Having competed at elite level for the past 30 years, Chloë advocates the health benefits of being muscular over being thin.

“In running and cycling there is a popular misconception that an increase in weight, whether it be from fat or muscle, makes us heavier and therefore slower. Increased muscle leads to an increase in weight, sure, but what people forget is that lean muscle tissue gives us strength – it provides greater storage for glycogen so we can perform at a higher intensity, and it helps us recover better. Many women are afraid of gaining muscle. But lean muscle is not only beautiful, but gives you strength to do more, using less energy. It’s also a defence mechanism, and it’s important for longevity in sport. Lean body tissue gives bone strength, connective tissue strength, and diminishes the onset of ageing. Being skinny is not only not a good look, it’s just not healthy!”

Treatment of RED-S

The complexity of RED-S is still being explored by medical, nutrition and health specialists. What is clear is that the athlete suffering from RED-S requires professional guidance from a multidisciplinary team  regarding nutrition and its relationship to sport and performance, and that the dietitian involved should be experienced in both sports nutrition and disordered eating. Coaches are certainly not trained to deal with the complex nuances involved with preventing and treating RED-S.

Low energy availability, ie not eating enough calories to support the combined energy demands of health and training, has more widespread adverse impacts on health and consequently performance in athletes. Also, low energy availability can impact male and female athletes of all levels and of all ages. (image credit: British Journal of Sports Medicine)


How to manage your energy intake to avoid RED-S 

  • Eat relative to your training load, increasing your carb intake on days of heavy training.
  • Pay attention to your recovery nutrition to restock your glycogen stores for your next day’s session and to protect lean muscle mass.
  • Avoid excluding entire food groups and following fad diets. Be sure to eat a good, balanced diet, rich in fresh, nutrient-dense foods.
  • Opt for real food rather than powdered supplements. Nothing beats the real thing!

Importance of body perception

As a closing point, but one that holds as much weight as good nutrition, is the importance of a healthy approach to how we look. Reiterating Chloë’s sentiments on skinny being neither healthy nor good looking, Rowena says we need to downplay the emphasis on weight and body shape in sports culture.

“We need to realise and become comfortable with our genetic differences, and not compare ourselves to the person next to us. Food needs to be seen as fuel for performance, rather than something to restrict and place tight rules around. We need to understand that sufficient fuel is essential for performance and long-term health. Rather than monitoring weight or leanness, we should focus on markers like energy levels, strength, how well we are recovering from training sessions, our perceived effort during training, and our moods; and we should be careful of blaming poor performance on weight.”