Athlete Eating Disorders: Signs, RED-S, and Path to Recovery

Eating disorders and disordered eating affect a striking share of competitive athletes, with prevalence estimates ranging from 0–19% in men and 6–45% in women depending on the sport and how broadly the behavior is defined. These are not just about body image or vanity; when an athlete chronically takes in less energy than training demands, the consequences cascade through nearly every organ system, a syndrome now called Relative Energy Deficiency in Sport, or RED-S. Understanding the warning signs, the biological fallout, and how recovery actually works matters for athletes, coaches, parents, and sports medicine professionals alike.

How Common Are Eating Disorders in Athletes

The numbers vary widely depending on sport type, competitive level, and how researchers define the problem. Across a broad review of the literature, disordered eating and clinical eating disorders have been found in up to 19% of male athletes and up to 45% of female athletes.¹ Those ranges are wide because the category itself is wide. “Disordered eating” covers everything from chronic underfueling and rigid food rules to clinical anorexia nervosa or bulimia nervosa, and researchers use different questionnaires to capture different slices of the spectrum.

Sports that emphasize leanness, including distance running, gymnastics, figure skating, cycling, and wrestling, consistently show higher rates of disordered eating. A systematic review found that six out of seven studies reported significantly elevated rates of disordered eating in lean sport types compared to the general athletic population.² But the same review noted that non-lean sports also had increased rates, which complicates the old assumption that only aesthetic and weight-class sports carry risk. Team sport athletes in soccer, basketball, and rowing can be affected too, especially when a coaching culture ties body weight to playing time or selection.

One counterintuitive finding is worth noting. A study comparing young female gymnasts to non-athlete peers found that the non-athlete group actually scored higher on a screening questionnaire for disturbed eating behaviors.³ This does not mean athletes are safe from eating disorders. It does suggest that the relationship between sport participation and disordered eating is not as simple as “sports cause eating disorders.” Structured training environments can sometimes be protective, at least for certain subgroups of younger athletes, while the risk factors shift as competition intensifies and body-composition pressures mount.

From the Female Athlete Triad to RED-S

For decades, the conversation about underfueling in sport centered on what was called the Female Athlete Triad: the combination of low energy availability, menstrual dysfunction, and reduced bone mineral density in women. The concept emerged in the 1990s and was useful, but it had blind spots. It implied the problem was limited to women, and it focused on just three health outcomes when the consequences of chronic underfueling are far broader.

In 2014, the International Olympic Committee convened an expert panel that replaced the Triad framework with Relative Energy Deficiency in Sport, or RED-S. The new term was deliberately chosen to capture two things the old one missed: the condition affects male athletes too, and its health consequences extend well beyond bones and menstrual cycles.⁴ Both the Triad and RED-S share the same root cause: low energy availability, defined as the energy left over for basic body functions after exercise expenditure is subtracted from dietary intake. When that number falls consistently below roughly 30 calories per kilogram of fat-free mass per day, the body starts rationing.⁵

The shift from “Triad” to “RED-S” was not just a rebrand. It changed clinical thinking. Instead of asking whether a female athlete had lost her period and had a stress fracture, clinicians began asking a broader question: is this athlete, regardless of sex, getting enough energy to support all the bodily functions that training demands? That reframing opened the door to recognizing problems in male athletes, para-athletes, and recreational exercisers who were previously overlooked.

Warning Signs That Something Is Wrong

Eating disorders in athletes are notoriously hard to spot. Many of the behaviors that signal a problem, like tracking macronutrients meticulously, exercising at high volumes, and maintaining a lean physique, are also considered normal or even praiseworthy in sport culture. That overlap makes early detection difficult for teammates, coaches, and sometimes even the athletes themselves.

The signs worth watching for generally fall into a few categories:

Eating patterns: Cutting out entire food groups without a medical reason, eating alone or avoiding team meals, anxiety about eating foods not on a rigid plan, skipping meals on rest days.
Training behavior: Exercising beyond what the program prescribes, panic about missed training sessions, inability to take a rest day without distress.
Physical changes: Unexplained weight loss, frequent illness or slow recovery from minor infections, recurrent soft-tissue injuries or stress fractures, feeling cold when others do not, dizziness on standing.
Menstrual changes: Loss of a previously regular period, or a period that never starts in a young athlete who has reached the expected age.
Mood and cognition: Increased irritability, difficulty concentrating during training, withdrawal from social activities, preoccupation with body weight or composition.

None of these signs alone proves an eating disorder. But clusters of them, especially when performance starts declining despite maintained or increased training, should raise a flag. The difficulty is that many athletes view pushing through discomfort as a virtue, and the culture of sport reinforces that instinct. A runner who loses her period may assume it is a normal consequence of hard training. A cyclist who drops weight and gets faster in the short term may not recognize that the improvement is unsustainable and damaging.

What Low Energy Availability Does to the Body

When the body consistently receives less fuel than it needs, it does not simply lose fat and carry on. It actively shuts down or suppresses functions it deems nonessential for immediate survival. The reproductive system is usually the first to go. Energy is diverted away from reproductive hormones as a survival mechanism, disrupting the signals that drive the normal menstrual cycle in women and testosterone production in men.⁶

Thyroid function takes a hit as well. Research in exercising women showed that levels of the active thyroid hormone T3 dropped sharply, by about 16%, when energy availability fell below a threshold between 19 and 25 calories per kilogram of lean body mass per day.⁷ Because thyroid hormones regulate metabolic rate, mood, and temperature regulation, this suppression helps explain why underfueled athletes often feel sluggish, cold, and mentally foggy. The drop is not gradual; it happens abruptly once the energy deficit crosses a threshold, which means an athlete can feel fine one week and terrible the next after a relatively small further reduction in intake.

Resting metabolic rate itself slows down. The body essentially learns to run on less fuel, which sounds like efficiency but is actually a state of suppressed function. A reduced resting metabolic rate is now recognized as one of the hallmarks of RED-S and is being explored as a potential diagnostic biomarker.⁸ The broader health fallout of long-standing low energy availability includes gastrointestinal problems, cardiovascular dysfunction, psychological symptoms, and compromised bone health, all of which can feed back into impaired training adaptation and increased injury risk.⁵

Bone Damage and Why It Matters Long After Retirement

Of all the consequences of RED-S, the skeletal effects may be the most sobering because they can be the hardest to reverse. When energy availability drops, the hormones that maintain bone, including estrogen, testosterone, thyroid hormones, and insulin-like growth factor 1, are all suppressed. The result is a shift toward net bone loss: the body breaks down bone faster than it builds it.⁹ In female endurance athletes, this loss has been documented at load-bearing sites like the hip and shin bone, raising the risk of stress fractures during a career and osteoporotic fractures later in life.

Young female athletes who sustain stress fractures at high-risk sites like the femoral neck or sacrum are especially concerning, because those fracture locations may signal an underlying pattern of low energy availability and poor overall bone health that warrants further investigation.¹⁰ A single stress fracture in a distance runner is sometimes dismissed as an overuse injury, but if it occurs at one of these high-risk sites, it should be treated as a potential red flag for systemic underfueling.

A retrospective study of elite athletes with RED-S found that they had significantly reduced bone density scores at the spine and hip compared to athletes without the condition. More detailed imaging revealed lower bone volume, reduced trabecular density, and thinner cortical bone, with the most pronounced damage occurring at the weight-bearing shin bone.¹¹ Trabecular bone, the spongy inner structure, was particularly affected, and it does not rebuild easily even after energy availability is restored. This means that an athlete who underfuels during the critical bone-building years of adolescence and early adulthood may carry a skeletal deficit for decades.

Male Athletes Are Not Exempt

RED-S was introduced in part because the Female Athlete Triad framework ignored men, and the evidence that male athletes suffer from the same condition has grown steadily. Low energy availability in male endurance athletes correlates with decreased testosterone, reduced bone density, and a lower resting metabolic rate.¹²

A case report of a 20-year-old male collegiate swimmer illustrates how severe the hormonal consequences can be. He was found to have strikingly low total, free, and bioavailable testosterone, with levels that would normally trigger concern for a serious endocrine disorder. After a diagnosis of RED-S, his sports medicine team increased his nutritional intake and moderated his training. His testosterone levels gradually returned to normal with minor weight gain.¹³ The case is a useful reminder that low testosterone in a young male athlete should not be automatically attributed to overtraining alone; chronic underfueling may be driving it.

The scope of the problem may be larger than many assume. A study measuring energy availability in highly trained male endurance athletes found that more than three quarters of them had mean energy availability below the 30-calorie threshold associated with RED-S. The same athletes showed suppressed levels of insulin, IGF-1, and leptin, along with markers indicating that their bones were in a state of net breakdown rather than building.¹⁴ Many of these athletes were not intentionally restricting food. They simply were not eating enough to match the demands of their training, a pattern sometimes called “inadvertent low energy availability.” The distinction matters: not all underfueling stems from a clinical eating disorder, but the physiological consequences are the same.

Screening Tools Built for Sport

Standard eating disorder screening questionnaires, like those designed for the general population, tend to underperform when used with athletes. An athlete who eats large volumes of food and exercises extensively may not flag on a questionnaire designed to catch restriction in a sedentary person. This has driven the development of sport-specific tools.

The Low Energy Availability in Females Questionnaire (LEAF-Q) is a 25-item screening tool designed to identify female athletes at risk for the Triad/RED-S. It targets energy availability, reproductive function, and bone health, and in validation studies it correctly classified athletes with acceptable accuracy: about 78% sensitivity and 90% specificity.¹⁵ In practical terms, it catches most athletes who have the condition while misidentifying relatively few healthy athletes as at risk.

For a tool that works across sexes, the Eating Disorders Screen for Athletes (EDSA) was developed and validated in both male and female athletes. It showed high sensitivity, correctly flagging about 96% of athletes who were at risk for eating disorders in both men and women, though its specificity was somewhat lower in women (64% versus 80% in men).¹⁶ The tool also held up across competition levels and sport types, which is useful for programs that serve athletes ranging from club-level to Division I. The trade-off with high sensitivity is more false positives, but in this context, over-screening carries far less risk than under-screening.

The Performance Paradox

One reason eating disorders persist in sport is that initial weight loss often does improve performance, at least temporarily. A lighter distance runner is, in the short term, more efficient. A lighter gymnast finds skills easier. This creates a perverse feedback loop where the early results reinforce the behavior. But sustained dietary restriction leads to a progressive deterioration of performance through several mechanisms: glycogen stores deplete, causing premature fatigue; dehydration triggers cramping; and the loss of lean muscle mass eventually reduces both strength and aerobic capacity.¹⁷

The timeline varies, but many athletes report a characteristic pattern: a period of weeks to months where they feel lighter and faster, followed by a plateau, and then a decline that they try to reverse by restricting further. By the time performance clearly suffers, the athlete may be deep into a clinical eating disorder with multiple organ systems affected. The hardest intervention conversations often happen at the plateau phase, when the athlete still feels the restriction is working but the physiological warning signs, missed periods, declining bone density, persistent fatigue, are already accumulating.

Body Composition Assessment and Its Risks

A sensitive and often contentious topic in sport is whether and how to assess body composition. Body fat testing, skinfold measurements, and weigh-ins are common in athletic programs, and there is legitimate sport-science value in monitoring body composition for performance and health. But the practice carries real risk. In a study of young athletes, about 43% of males and nearly 69% of females were classified as at risk for eating disorders based on screening questionnaires, and body fat percentage was a significant predictor: for every one-unit increase in body fat percentage, athletes were slightly less likely to be classified as at risk.¹⁸ In other words, the leanest athletes in the sample were the ones most likely to screen positive for eating disorder risk.

This raises practical questions for coaches and support staff. If you measure body fat and share numbers with athletes, you may inadvertently fuel restriction in those already at risk. Some sports organizations now recommend that body composition data be managed only by qualified practitioners, shared with athletes cautiously and in context, and never used as a performance target or a condition of selection. The evidence suggests that education matters too: athletes with better sport nutrition knowledge tend to make more informed choices about fueling, but knowledge alone does not prevent disordered eating when the surrounding culture rewards leanness.

What Recovery Looks Like

Recovery from an eating disorder in an athlete is complicated by the fact that unlike most patients recovering from eating disorders, athletes are expected to return to the environment that contributed to the problem. The training facility, the coach, the competitive pressures, and the body-composition expectations do not disappear. This means recovery must address both the medical and psychological dimensions, and it typically requires a team approach involving a physician, a sports dietitian, and a mental health professional with experience in eating disorders.

On the nutritional side, three dietary strategies have been proposed for athletes recovering from energy restriction: a gradual increase in energy intake to maintenance requirements, unrestricted eating, or an immediate return to maintenance energy levels.¹⁹ Each has trade-offs. A gradual increase may feel more manageable psychologically but delays physiological recovery. Unrestricted eating can restore hormonal function faster but may trigger anxiety in athletes with eating disorders. An immediate jump to maintenance calories requires close monitoring to avoid refeeding complications in severely restricted individuals. The right approach depends on the severity and duration of the restriction, the sport’s timeline, and the athlete’s psychological readiness.

One of the clearest markers of recovery is the return of suppressed hormones. In women, the resumption of regular menstrual cycles is a strong signal that energy availability has been adequately restored. In men, as the case of the collegiate swimmer showed, testosterone levels can normalize with relatively modest increases in weight and nutrition. Bone density recovery is slower and less certain. While some improvement in bone markers can be seen within months of correcting energy intake, the structural changes documented in advanced imaging studies suggest that full skeletal recovery may take years, and in some cases bone density may never fully return to normal.

Orthorexia and Exercise Addiction in the Athletic Context

Not all disordered eating in athletes fits neatly into classic diagnoses like anorexia or bulimia. Two patterns that show up frequently in athletic populations are orthorexia, an obsessive fixation on eating only “clean” or “pure” foods, and exercise addiction, where training becomes compulsive and continues despite injury or harm. Research has found that orthorexia overlaps strongly with both restrictive and muscularity-oriented forms of disordered eating, and the overlap is even more pronounced in women.²⁰ The same study found that orthorexia predicted both psychosocial impairment and psychological distress, while exercise addiction on its own did not show unique links to clinical harm once other eating behaviors were accounted for.

For athletes, this is worth understanding because orthorexic tendencies can masquerade as healthy eating. An athlete who eliminates processed food, then dairy, then gluten, then cooked food may be praised by teammates and coaches for their discipline while actually spiraling into a pattern that restricts energy intake and nutrient diversity. The line between performance-oriented nutrition and pathological restriction is genuinely blurry, and it shifts depending on context.

Para-Athletes and Overlooked Populations

Most of the research on eating disorders in athletes has focused on able-bodied populations, but a survey of elite para-athletes found that factors associated with RED-S are present in that population as well, regardless of sex or sport type.²¹ Awareness of RED-S among para-athletes was low, and the consequences of low energy availability in this group are poorly understood, partly because standard screening tools were not designed with para-athletes in mind. An athlete who uses a wheelchair, for example, has different energy expenditure patterns, body composition norms, and bone-loading characteristics than an ambulatory athlete. Existing questionnaires and thresholds may not apply cleanly.

The high prevalence of RED-S risk factors observed in para-athletes suggests that screening and education efforts developed for the general athletic population need to be adapted. This is an area where the research is genuinely thin, and para-athletes may be slipping through the cracks of a system that was built for a different body. As Paralympic sport continues to grow in visibility and competitiveness, closing that gap becomes more urgent.