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This story discussed eating disorders. If you or someone you care about is struggling with an eating disorder, you can contact the National Eating Disorders Association (NEDA) helpline at 1-800-931-2237. For a 24-hour crisis line, text “NEDA” to 741741.
For Jake Riley, the trouble started in 2019. He’d always thought of himself as “big” compared to the average pro runner. During his buildup to the U.S. Olympic Marathon Trials in February 2020, and again when he prepared for the Olympics, he decided he might run faster if he closed the gap.
So he trimmed what he deemed as extras from his diet—juice, soda, and dessert, mostly—and gradually lost a few pounds.
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At first, the strategy seemed to pay off. He ran a personal best 2:10:02 at the Trials, finishing second and making the Olympic team. But he didn’t realize it at the time, these tweaks dipped his carbohydrate and calorie intake below the substantial energy demands of marathon training—a risky condition known as relative energy deficiency in sport, or RED-S.
His body, lacking fuel, first stopped responding to his long runs and workouts. Soon, he racked up a string of disappointing races, including a 2:16:26, 29th-place finish in Tokyo and 46:26 for 35th place in the Gate River Run 15K the following March. His Achilles tendons and hamstrings ached, he couldn’t sleep, and his mood soured into one he described in a May 31 Instagram post as “depression-adjacent.”
Riley and his coach, Lee Troop, spent a few months seeking answers for his symptoms. Was it a training issue, post-Olympic blues, injuries, a thyroid problem?
“There’s a whole bunch of factors that go into what makes a runner good,” Riley told Runner’s World. “Because I was only doing the restricted calorie eating in very short slots, and I did not do it for most of the time, it wasn’t something we were looking at.”
He didn’t put all the pieces together until March 2022, when he received a diagnosis of RED-S from his medical team. Now, with the benefit of hindsight, he’s aiming to help other runners avoid the same trap.
Lifting the veil
Far too many athletes and coaches are unaware of the dangers underfueling poses to performance and health, Riley, now 33, believes. “I knew that RED-S was a possibility. But I kind of thought you really had to try—you had to be essentially anorexic or bulimic, or really restricting yourself,” he said.
In fact, you don’t have to have disordered eating, an eating disorder, or even be aiming to lose weight to have RED-S. And the issue affects recreational as well as elite athletes of all body sizes, said dietitian and pro runner Maddie Alm, M.S., R.D, who diagnosed Riley.
Statistics suggest more than one in five athletes of all types are underfueling—either not eating enough overall or not consuming enough of the right foods. The issue is more common in running and other endurance sports, where energy requirements are significant and weight has been overemphasized as a factor in performance, said Riley Nickols, Ph.D., a sport psychologist and certified eating disorder specialist at Mind Body Endurance.
In fact, based on what he has learned, Riley now realizes he may have been flirting with danger for a long time. “I’ve probably never been fueling my training enough,” he said.
Spotting the warning signs
Most experts believe underfueling and RED-S are significantly underreported, especially in men, who tend to think they’re less susceptible, Alm said. This bias may influence clinicians, too, who then overlook warning signs in men or attribute them to other causes.
After all, male athletes lack one of the clearest and best-known signs of RED-S: irregular or missing periods. But even in women, an erratic cycle usually isn’t the first indication you’re underfueling, Alm said.
Two earlier symptoms she often sees are trouble sleeping and mood shifts. Athletes who usually sleep soundly suddenly can’t fall asleep or stay there; when they’re awake, they’re cranky or sad. “They’re just flying off the handle for no reason or crying for no reason,” Alm said.
Another red flag is frequent illness, especially upper respiratory infections like colds and bronchitis; a lack of energy and nutrients impairs immunity.
From there, the implications become more serious: Performance stalls or declines, no matter how hard an athlete trains. Bodies under stress from lack of fuel produce higher levels of the hormone cortisol, which breaks down muscle and thwarts any gains from workouts, Alm said.
In addition, suppression of sex hormones like testosterone, estrogen, and progesterone decrease adaptations to training, zap libido, and interrupt menstrual cycles; alterations in thyroid hormones can affect energy levels and metabolism.
Hormonal imbalances also affect bone health, eventually leading to low bone density and stress fractures. And because nutrient deficiencies also weaken tendons and other tissues, underfueled runners are prone to many other types of injuries, too, said Starla Garcia, R.D., an Olympic Trials marathoner and registered dietitian based in Houston.
Gastrointestinal problems, including constipation and bloating, may arise and exacerbate the problem, causing athletes who feel poorly to eat less. And what they do consume isn’t absorbed well, thanks to chronic inflammation and depletion of digestive enzymes. Blood tests may reveal low levels of vitamin D, iron, B12, and other vitamins and minerals, even if athletes haven’t changed their diets much or are taking supplements.
If you develop these signs, experts recommend talking with someone knowledgeable—a dietitian, sport psychologist, or other clinician with expertise in managing nutrition and eating issues in athletes. “Athletes have a high attunement to their bodies, which is good,” Nickols said. “But I think awareness without timely responsiveness is kind of for nothing.”
Confirming the diagnosis
The turning point for Riley came after the Gate River Run in March. A few weeks later, after limping through about 20 minutes of a 2.5-hour long run, he jogged up to Troop to get a water bottle—then broke down crying.
“At that point, I was like, ‘I can’t keep doing this,’” he said. “I feel like I’m putting in so much effort to run so poorly, and I just cannot turn a corner.”
That experience—and a Runner’s World article about thyroid problems in runners—convinced Riley to seek a medical explanation. He made a doctor’s appointment and got bloodwork done.
His symptoms aligned so closely with Jared Ward’s description of Hashimoto’s disease, Riley at first thought he might also have hypothyroidism. Because the signs overlap and RED-S can cause some changes in thyroid hormone levels, the two conditions are often confused, especially by doctors who don’t often work with athletes.
“The trickiest part with RED-S—because it’s so sneaky and there are so many different symptoms—is that a lot of times what ends up happening is the athlete and the treatment team treat the symptoms,” Alm said. Runners might rack up prescriptions and supplements—antidepressants for mood, melatonin for sleep, thyroid hormone to correct imbalances—without addressing the underlying cause.
To identify RED-S, Alm reviews athletes’ symptoms. She compares their intake to the needs she calculates for them, looking for gaps. (Runners are most prone to fall short on total calories and carbohydrates, she said.) She asks about their relationship to food and listens for red flags, such as choosing non-fat dairy to cut calories or suddenly deciding to avoid entire food groups.
In Riley’s case, the answer was quickly clear. His thyroid hormone levels were relatively normal, but he had persistently low vitamin D and iron, despite supplementing. His doctor suggested he meet with Alm. “After a 20-minute conversation, she said RED-S,” Riley said.
At first, he was taken aback. But he trusted Alm’s expertise, and her interpretation of the timeline. “It’s not always going to happen when you’re actually doing the restricting,” he said. “And unless you actively try to work your way out of it by really changing your eating habits, you’re just going to kind of stay in that hole.”
Refilling the tank
The treatment for RED-S seems straightforward: Realigning intake with expenditure by eating more, training less, or both. But how easy that is to do depends on factors such as how long athletes have run at a deficit and what caused the condition in the first place.
“A lot of people fall into RED-S very innocently,” Garcia said. Perhaps they’re new runners who begin with a goal of “getting in shape,” or experienced athletes who increase their mileage or intensity without realizing they also need to eat more. If runners catch the problem early, the fix is relatively quick, Alm said.
But what begins with a lack of knowledge can swiftly slide into disordered eating or eating disorders. Why? At first, many runners may see weight loss and improved performances before symptoms begin. “I ran really well at the Trials,” Riley said. “Whether or not it was because of that, or how well my training had been going, who knows?”
That type of experience, along with pressure from ill-informed coaches and a thinness-obsessed culture, can turn what began as an oversight into an ingrained mindset that’s harder to shift, Nickols said.
Olympians aren’t immune from these pressures: “If the top runners are lighter than me, even if they are my same height—if I am not trying to get down to that, then I am leaving speed on the table. [That] was kind of my perception,” Riley said.
What he failed to factor in was the arbitrary nature of his goal weight, and the cost of getting there. “Where is that weight coming from? What are you getting rid of to get that loss? I didn’t really consider that, either,” he said.
Garcia and Alm note that each runner has a unique physiology, a different body composition at which they’re healthiest and fastest. They recommend seeking out reliable advice before making dietary changes, especially if you’re restricting your intake or eliminating food groups to which you aren’t allergic.
Riley agrees—in fact, athletes tempted to chase a number on the scale, a mileage or pace goal, or any other metric should run their ideas by an expert. “I don’t think we’re always the most reliable judges of what we actually need,” he said. “Being transparent with people that know what they’re talking about, and that you trust and have your interests at heart, is really, really valuable.”
The line between discipline and disorder is a fine one, Nickols said. If you’re having trouble following expert advice or increasing your intake, you may have crossed it. “If there’s a lot of resistance around [fueling], or emotional distress that happens afterward, that’s a sign that something’s going on there,” Garcia said.
To destigmatize and recontextualize disordered eating and eating disorders, Nickols refers to them as “metabolic injuries.” Just like physical injuries, they require rest, rehab, and a team approach to treatment, including a dietitian and/or sport psychologist specializing in disordered eating.
“It’s scary to ask for help or to admit that you have a problem in the first place. But it will help you so much more in the long run,” Alm said.
Planning a comeback
Riley quickly adjusted his habits, setting alerts to eat every few hours and adding back what he’d cut out, plus some extra pasta, bread, and cereal. For him, the shift hasn’t been psychologically difficult—if pasta is what’s required to win, he’ll oblige.
The effects weren’t swift enough to improve his performance at the Boston Marathon a month later. Riley knew he might not be fully recovered but still wanted to run. At mile 6, he slowed, going from a 5-minute pace to a 2:30:48 finish (5:45 pace).
Currently, he’s between surgeries to repair a defect called Haglund’s deformity, which leads to Achilles problems, in both heels. (One is a revision of a procedure he had done in 2018.)
While injuries can be frustrating and exacerbate anxiety around food, they can jump start recovery from RED-S if approached correctly, Alm said. Training less and eating more can promote tissue repair and reset your physiology and psychology. “Using that time to heal your body from the inside out will really allow you to get back and stay injury-free,” she said.
Right now, Riley isn’t sure how his next chapter will play out. Will he rise once again from the challenge, or serve as a cautionary tale of a career cut short? He’s betting on the former, hoping he can recover in time to run a couple more marathons before the Olympic cycle in 2024.
To get there, he’ll harness the same traits that may have gotten him into trouble—commitment, a willingness to sacrifice, a love of the grind—to bring him back out. “I think there’s plenty of talent left there,” he said. “I’ve just got to find a way to access it again.”
Cindy is a freelance health and fitness writer, author, and podcaster who’s contributed regularly to Runner’s World since 2013. She’s the coauthor of both Breakthrough Women’s Running: Dream Big and Train Smart and Rebound: Train Your Mind to Bounce Back Stronger from Sports Injuries, a book about the psychology of sports injury from Bloomsbury Sport. Cindy specializes in covering injury prevention and recovery, everyday athletes accomplishing extraordinary things, and the active community in her beloved Chicago, where winter forges deep bonds between those brave enough to train through it.
