The Zommunique logo June '23


The Sensitive Issue of Low Energy Availability in Cycling

Under-fueling negatively affects cycling performance and your health in only days and will cause permanent damage to your body and mind.

Cycling is a weight-sensitive sport. Using “sensitive” in this context denotes the perceived correlation between body composition and success. Below the surface, it underlies the pressure cyclists experience to alter their body weight by manipulating nutrition and exercise to enhance performance. 


The athlete’s psyche is often fragile and can seek shortcuts by compromising nutrition and exercise, causing low energy availability. Unfortunately, disordered eating and eating disorders underpin the situation’s sensitivity with severe consequences.

Low Energy Availability in Cycling riders on a bridge
Photo: TLBVelo photography

Low Energy Availability in Cycling—The Dilemma

Telling a highly motivated and driven cyclist that their questionable nutrition habits will cause harm is sometimes not enough to change their behavior. Athletes sacrifice potential future problems for success in the here and now. One language all competitive cyclists speak is speed; if performance is limited, that’s the lightbulb moment.

Body mass (BM) and body composition or power-to-weight ratio (w/kg) directly affect performance in weight-sensitive sports like cycling. Consequently, well-planned and closely supervised periods of moderate low energy availability (LEA) will enhance performance and reward the aberrant behavior.  

Low Energy Availability in Cycling—The Perils

Unfortunately, many athletes fall victim to the perils of severe, prolonged, or chronic LEA, which leads to Relative Energy Deficiency in Sport (REDs), and poses a permanent adverse risk to the health and performance potential of the athlete.

Scientists, coaches, sports nutritionists, and the athlete’s performance team are more aware of the dangers of RED-S across all cycling disciplines as athletes have stepped up to share their experiences, and there’s more research. Despite this, the issue is insidious and requires more education and awareness.

Low Energy Availability in Cycling race finish on top of a hill
Photo: TLBVelo photography

Low Energy Availability in Cycling—The Prevalence

Eatas 42 percent. Despite the prevalence, a 2022 paper published by a Durham University research group in BMC Sports Science, Ming disorder (ED) and disordered eating (DE) risk in female athletes, especially those participating in endurance sports, is estimated to be as high edicine, and Rehabilitation contends, “Female cyclists are at risk of developing Eating Disorders (EDs), and they are aware of this risk.

Low energy availability and RED-S is not only a female thing, and it isn’t limited to traditional elite cyclists. A recent study identified RED-S in male cyclists, resulting in adverse health risks, including low testosterone, osteoporosis, and performance deficits. RED-S in male athletes is receiving greater awareness and is more widespread than once believed.

On many virtual cycling platforms, performance links to weight sensitivity through w/kg as a speed-determining metric. What’s more, virtual cyclists are prone to under-fueling. A 2022 study published in the British Journal of Nutrition suggests that 75% of virtual cyclists and esports competitors consume no carbohydrates during racing and training sessions.

cyclists riding past an outdoor dining establishment
Photo: TLBVelo photography

Low Energy Availability in Cycling—The Damage

Despite the increased awareness and study, the detrimental effects of LEA on sports performance and health still need to be elucidated. In a February 2023 narrative review, researchers described the impact of LEA on athlete outcomes. By characterizing the short-, medium-, and long-term vulnerabilities, the scientists set out to give a clear picture of the performance risks. But first, a few points of clarification.

What is Energy Availability (EA)?

It may seem like a simple question, but it is far from it. Scientists define EA in the literature as the difference between energy intake (EI), what we consume, and exercise energy expenditure (EEE), what’s burned off relative to fat-free mass (FFM). 

FFM is everything in our body except for fat—water, organs, bone, and muscle. FFM equals weight (kg) x (1- (body fat %)/100)

Fairly straightforward, right? The blurry part is that there needs to be more consensus on appropriate EA levels in female and male athletes. 

Research suggests that less than 30 kcal/kg of FFM per day is the LEA threshold, but the strict cut-off is controversial, with many confounding variables. Therefore, researchers suggest an EA range between 35 – 45 kcal/kg.ffm is more appropriate and use the above figure as a starting point. 

Now that we cleared that up. What is it?

What is Low Energy Availability (LEA)?

Durham University researchers called on a team of clinical sports endocrinologists, a sports research scientist, a registered sports performance dietician, competitive male cyclists, and coaches to simplify it. The research team clinically evaluated energy availability according to the following parameters.  

Chronic low EA: Disordered eating requiring intervention from a sports performance dietician, a diagnosed eating disorder, or intentional restrictive nutrition to achieve substantial weight loss (>7%) within five weeks and sustained over more than a cycling season (>12 months).

Acute intermittent low EA: Limited fuelling around training (e.g., weekly fasted rides), on a background of non-restrictive nutrition, and minor variations of body weight (<5%) during a cycling season.

Adequate EA: No restrictive nutrition practices and steady weight.

Using this criteria and others as parameters, the researchers laid out the risks to performance—a language all competitive cyclists speak.

Performance and Health-Related Consequences of Low Energy Availability in Cycling

Short Term

Alarmingly they found that low energy availability for a few days to weeks poses immediate performance limitations. Excessive fatigue and inability to adapt to training interventions result from short-term low skeletal muscle glycogen. 

You will go slower. Do you hear that cyclists?

Reductions in bone formation, weakened immune function, lower iron absorption, and increased inflammatory markers start in days. As do impaired menstrual function, reduced estrogen levels and metabolic rate, elevated cortisol, and lower testosterone: cortisol ratios.

The bodies of most normal healthy individuals will detect the beginning of an issue and send pangs of hunger to correct it. Cyclists aren’t most normal individuals and push through. That’s when it gets more real and really where many athletes fall.

Medium Term

The researchers described medium-term LEA between weeks to months. In addition to the progression of adverse outcomes noted above, athletes have difficulty recovering and become prone to overuse injuries and overtraining. 

A 2011 paper published in the Journal of Environmental Research of Public Health estimates 48% of individuals suffering from eating disorders have an exercise compulsion. Out-of-control exercise behaviors can manifest in many ways, and there are no set diagnostic criteria for overtraining syndrome.

Confounding the issue, researchers suggest in a 2021 study published in Sports Medicine that some athletes exhibiting symptoms of overtraining aren’t training too much. Instead, they’re not eating enough to fuel their training properly, causing LEA.

Athletes exhibit mood disturbances such as anger, confusion, diminished cognitive ability, sleep disturbances, and depression.

The imminent danger to athletes exhibiting medium-term signs is the inability to snap out of it with a few heaping helpings. The damage takes time and a conscious effort to correct. 

Long Term

The catastrophic consequence of chronic LEA exposure over months to years is an increased risk of developing RED-S. Or worse, when an athlete spirals out of control, the psychological toll can manifest in an eating disorder and is an emergent situation.

Low Energy Availability in Cycling
Photo: TLBVelo photography

Low Energy Availability in Cycling—The Extreme Risk

Extreme dieting behaviors that persist for months or years fall into a continuum. The range of abnormal eating patterns seen in competitive cyclists begins with disordered eating (DE) and progresses in severity to clinical eating disorders (ED). 

Disordered eating practices, found in 20% of female and 8% of male elite athletes, include short-term restrictive diets (<30kcal/kg per day). The progression ends with clinical eating disorders, including anorexia nervosa, bulimia, and binge disorder.

Low Energy Availability in Cycling-The Conclusion

The sensitive nature of the issue is what makes it dangerous. Many athletes are apprehensive about asking for help or identifying the signs in themselves. Eating disorders are mental illnesses that sufferers cannot detect. 


If you feel you may have a disordered eating problem, or you don’t know, you are not alone, nor is there any shame in admitting it. Contact the American National Eating Disorders Helpline for guidance and support.


Denying that a problem exists will not make it go away. All members of an athlete’s performance and healthcare team are essential in educating, preventing, and treating at-risk individuals. A cyclist’s performance will suffer in the short term, and if they don’t make changes will permanently damage their bodies.

I know it’s sensitive, but Care to Share?

Knowing that you are not alone is half the battle. Please share your experience.

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5 months ago

Good summary article. I’m only just starting to read up on EA as a metric. Makes sense and if I could summarize for myself seems to be a different and FFM-specific take on the global 2,500 kcal/day or equations on RMR? Arguably better?

Think you need a “/” in the What is Energy Availability section:… 35-45 kcal/kg.fmf

Was interesting to read the high end of that spectrum is for sedentary females vs the low end for recreationally active males. I suppose it comes down to division by FMF.

Thanks Chris.

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