Athletes are often very disciplined. In addition to practicing for hours every week (or even every day), many spend additional time training or doing other workouts to prepare for the big game or competition. They may also be mindful about what they're eating, particularly before and after their sport, to ensure they can perform and recover properly.

This is all healthy—until it isn't. There's a fine line between being disciplined and adopting a regimen that actually harms health and performance. All too often, athletes may be undereating and not realize it.

Camilla Blanton, RD, Lead Registered Dietitian at Equip, explains that undereating is when “there's a mismatch where the energy demands of the sport or activity are not being matched by the athlete's energy intake.” Essentially, it occurs when you're not giving your body the nutrients it needs to function, let alone perform at its best for the sport.

Studies show this tends to be pretty common: according to one meta-analysis, about 45 percent of athletes have “low energy availability” (another term for undereating). Making things more concerning, although not everyone who underfuels has an eating disorder, athletes in general have two to three times the risk of developing an eating disorder compared to their non-athlete peers.

Everyone needs a certain amount of calories and the right balance of nutrients for their body to function day in and day out—and athletes need even more because of all the energy they expend. When athletes undereat, it not only has a negative impact on their physical (and mental) health, but also hurts their athletic performance.

Whether you're an athlete, parent of an athlete, coach, or trainer, it’s important to understand the causes, risks, and solutions to undereating in athletes. Read on to learn why athletes may not realize they're not eating enough, signs and risks of undereating, and how athletes can ensure they're getting balanced nutrition for peak performance.

Why athletes may be undereating without realizing it

In some instances—like in the case of an eating disorder—an athlete might know that they’re not eating enough. But in many cases, athletes are completely unaware that they’re underfueling. There can be a number of reasons for this, including the factors below.

Pressure to maintain a certain body image

No matter the sport, “a lot of the time, the reason for undereating might be cultural messaging from coaches, trainers, and other people of influence,” Blanton says. We know all too well how the media loves to talk when an athlete (or other celebrity) loses or gains weight, and this can cause younger athletes in the same sport to think they need to look a certain way to succeed. Additionally, coaches and trainers might make comments about an athlete's weight, body shape, or something they see them eating. It doesn't matter if the comment is directed at the athlete or one of their peers, if it’s critical or complimentary, or if it’s well-intentioned: the message to look a certain way or eat or not eat certain foods can affect everyone who hears.

Social media and the recent change in name, image, and likeness (NIL) rights for college athletes has heightened body dissatisfaction, Blanton adds. “There's an emphasis on leanness and athletic aesthetic, and you see that image through social media, as far as who's getting deals. And that means you need to have a social presence, which means you constantly need to see images of yourself, which is not helpful.”

Ignoring body cues

“There's a lot of messaging in the athlete world about pushing through. A lot of people hear, 'No pain no gain,'” Blanton says. “It can teach athletes of any age to ignore their body cues.” This may lead them to ignore feelings of hunger, when their body is trying to say, “We're not getting enough nutrition,” she adds.

Misconceptions about energy needs

Nutrition is highly individualized. Each of us has different needs. Many athletes may simply underestimate how much they need to eat to support their activity level. Part of this may be due to diet culture and misinformation from social media, where anyone can claim to be an expert and recommend their eating plan. Additionally, not all trainers are well educated about nutrition, and they may share unhelpful tips.

Appetite suppression after intense workouts

Some athletes may undereat simply because they don't feel hungry after training. Various hormones play a role in hunger and fullness, and research shows that these hormones change after exercise. For example, short bouts of exercise cause levels of ghrelin (the hormone that causes hunger) to fall and levels of peptide YY and glucagon-like peptide-1 (two hormones that increase fullness) to increase. Intense activity may have an even greater effect at reducing ghrelin levels, leaving athletes less hungry after harder workouts.

Signs of undereating in athletes

So how can you tell if you, your child, or an athlete you work with may not be getting proper nutrition? “It doesn't take a lot for the body to show physical signs and symptoms of low energy availability,” Blanton says. Watch for the below symptoms of under-fueling in sports—if you notice more than one, it's probably time to talk to a healthcare professional.

Physical symptoms of underfueling

• Chronic fatigue and low energy levels
• Frequent injuries, such as stress fractures
• Recurring injuries
• Loss of menstruation
• Frequent illness
• Missing practice or training due to illness
• Trouble sleeping
• Abdominal pain and constipation

Performance-related indicators

• Overall decreased performance (in power, endurance, strength, speed, coordination, agility, etc.)
• Plateauing in training
• Regressing in strength and endurance
• Struggling to complete workouts
• Slower recovery times
• Slower heart rate

Psychological and emotional red flags

• Increased irritability or anxiety
• Depression
• Preoccupation with food and exercise
• Social withdrawal or avoiding meals with others
• Emotional dysregulation

Risks of chronic undereating for athletes

Underfueling in athletes can lead to serious long-term risks, which include physical, psychological, and athletic consequences. This is true for athletes who underfuel consistently as well as those who only do it intermittently, like skipping snacks or nutrition after a workout.

Physical health risks

• Relative energy deficiency in sport (RED-S): RED-S occurs when someone doesn't eat enough to support their level of everyday and physical activity. In one study of elite and pre-elite female athletes, 80 percent showed signs of RED-S. These symptoms include a decline in performance, fatigue, injuries, GI problems, and trouble sleeping and concentrating. RED-S can lead to bone loss, delayed growth, dizziness, slowed metabolism, and loss of menstruation.
• Hormonal imbalances: Undereating suppresses the release of gonadotropin-releasing hormone (GnRH). This causes the body to produce less luteinizing hormone (LH) and follicle-stimulating hormone (FSH), hormones that regulate reproduction and menstruation.
• Weakened immune system: Low energy availability boosts production of reactive oxygen species, unstable molecules that can damage cells and impair immune response.
• Digestive issues: Constipation and abdominal pain can occur if an athlete is underfueling, due to slower digestion.

Performance-related risks

• Loss of muscle mass: Low energy availability reduces muscle protein synthesis, the process where the body repairs and builds muscle. Since working out damages muscle, this can cause you to lose muscle. You need muscle for athlete performance as well as to support bone health.
• Bone loss: For one, athletes who undereat may not be consuming sufficient calcium, vitamin D, and other nutrients to support bone health. And second, if an athlete loses their period, their body is producing less LH and FSH. These hormones regulate estrogen production, which we need for bone growth. Decreased levels can lead to bone loss and possibly osteoporosis.
• Injuries and extended recovery times: Because of the effects on muscle and bone, athletes who undereat are more likely to sustain injuries of all kinds. They often keep having the same injury, Blanton adds.

Psychological risks

• Depression and anxiety: Various nutrients impact brain function in positive and negative ways. So if you're not eating a varied diet or enough of certain nutrients, it may increase the risk of depression and anxiety.
• Eating disorders: “Sports participation doesn't cause eating disorders, but it can be a contributing factor to maintaining eating disorders,” Blanton says. “We see a lot of problematic eating behaviors in athletes.” For example, having strict rules about food and exercise might eventually develop into orthorexia, and restriction may set someone up to later binge. At the same time, “athletes are less likely to receive a diagnosis and treatment, even though we know they have a higher risk of eating disorder,” Blanton adds. This is at least in part because many disordered behaviors—like controlling food intake and exercising obsessively—can seem normal or even “good” in the context of sports.

Practical nutrition and recovery tips for athletes

In a world where we're often being told what not to eat, it can be difficult to figure out what to eat—especially what to eat more of if you're an athlete. Although each person's needs are unique to their body and their sport, below are some starting guidelines for athletes to avoid underfueling.

Recognize increased energy needs

You may need to eat more than you think. “A lot of times, athletes are eating three meals plus snacks throughout the day, but their nutritional needs are so high, that's not enough,” says sports dietitian and eating disorder expert Tara Ostrowe, MS, RD, CSSD. If you increase exercise duration, frequency, or intensity, you also need additional energy, Blanton adds. Lastly, if you notice any of the symptoms of underfueling listed above, there's a good chance your body is saying it needs more food, she says.

Build a balanced plate for peak performance

Most “diets” advise reducing our intake of certain nutrients, especially carbohydrates. But “we should never cut out food groups, because all of them combined gives our body exactly what it needs to support performance,” Blanton says. “In particular, carbs provide energy, protein supports recovery, and fats help unlock vitamins in certain foods.” So athletes need all the macronutrients (carbohydrates, proteins, fiber, and healthy fats), ideally at every meal, she says. Also, don't neglect fruits and vegetables, which provide micronutrients that play a role in muscle growth, energy production, and recovery.

Think food first

“A lot of athletes think they need supplements, but we want to take a food-first approach because food is synergistic. Different macronutrients work together to help your body unlock other nutrients at times,” Blanton explains. If you find it challenging to get all the nutrition you need from food, see a registered sports dietitian. They can help you see if you could make any changes to your diet first, and if there are still gaps, discuss supplements. “Even if it's just a one-session assessment to get an idea or framework of what your body needs and what that looks like,” it helps, Ostrowe says.

Time it right

Most athletes require pre- and post-workout nutrition to properly fuel and recover. “In terms of performance and feeling your best regarding endurance and energy for your workout, pre-workout nutrition is important. You'll notice you get a better workout and reduce the risk of injury,” Ostrowe says. “And post-workout nutrition will help your body recover so you're able to perform at your best day after day and prevent injury.”

Understand that recovery is part of training

Recovery is part of training. Rest days help your body recover and tend to promote better sleep. In turn, sleep is essential for both physical and mental health. Too little sleep increases stress hormones, negatively affects muscle repair, and leads to fatigue.

What to do if you’re struggling with undereating as an athlete

Given all the mixed messages athletes can receive about body shape, weight, exercise, and nutrition, it's understandable that so many athletes grapple with undereating at times. If you think or know you're not consuming enough to fuel your activity, consider the following tips to help you give your body and mind the fuel you need to thrive.

Recognize the need for support

It's not always easy to determine if you're undereating. Blanton suggests asking yourself questions about your performance and habits like:

• Am I running out of steam or power during my training or workouts?
• Do I feel frustrated with my athletic performance?
• How am I doing now versus the start of the season?
• Do I feel low energy, weak, or tired all the time?
• Am I having trouble sleeping?
• Have I stopped getting my period?

Even if you're honest with yourself, “having the insight and understanding that there's a mismatch between your activity level and your eating can be difficult,” Blanton says. That's where professional help comes in. Seek out a sports dietitian, who can help you navigate your personal nutritional needs. And if you need emotional or psychological support, find a therapist who works with athletes and is knowledgeable about disordered eating.

Find eating disorder-informed healthcare providers

Athletes who underfuel don't necessarily have eating disorders. However, working with sports dietitians, therapists, and other providers who are eating disorder-informed often leads to better outcomes.

For example, professionals with a health at every size (HAES) approach take the focus off of someone's weight and body size and instead focus on their health and well-being. “We know if we focus on health-promoting behaviors, such as eating enough food to support our sport performance, we will see a positive benefit to one's health,” Blanton says. “On the other hand, seeing a provider who's heavily weight-focused could negatively impact someone, even if weight has never been a concern for them.” This is especially helpful for athletes in weight-centric sports like wrestling or ballet.

Build a positive relationship with food

A dietitian can help you shift your mindset about food to be more neutral. “All foods can be included in one's dietary intake,” Blanton says. “We want to have variety and options for macronutrients.” And although you may have heard the saying “food is fuel,” not everyone finds this helpful. “If food is just fuel, it can create a limiting mindset. Food should also be fun, and fueling should also be fun to some extent and include foods that taste good,” Blanton says. Overall, work toward a place where you can be flexible with your eating and honor what your body desires.

The Equip takeaway: Honoring your energy needs as an athlete

Athletes need proper nutrition to fuel performance and recovery. However, many may be undereating, either because they don’t realize how much they need to eat, because of societal pressures, or because of an eating disorder. “There's a lot out there about what a body should look like for this or that sport, but that doesn't equal performance or how someone will succeed in that sport,” Ostrowe says.

Undereating can negatively impact performance and every system of the body, from the skeletal and immune system to the GI tract, cardiovascular health, fertility, and mental health. On the other hand, if athletes forget about a number on the scale or a certain body shape and instead put their focus on consuming a balanced diet, training without overtraining, and giving their bodies time to recover, “they'll have top performance,” Ostrowe says.

If you're struggling with undereating as an athlete, know that help is available. We recommend finding a HAES sports dietitian who also understands eating disorders. You can also take this five-minute screener to assess if you may have an eating disorder. Either way, seek out help now, before your performance and your health suffer.

FAQs

What are the most common signs of undereating in athletes?

The most common signs of undereating in athletes include more frequent injuries, recurring injuries, fatigue, frequent illnesses, and a plateau or decrease in athletic performance.

What are the risks of undereating in athletes?

The risks of undereating in athletes includes relative energy deficiency in sport (RED-S), a weakened immune system, digestive problems, loss of muscle mass and bone mass, increased risk of injuries and extended recovery times, and the potential to develop depression, anxiety, or an eating disorder.

How can undereating affect athletic performance?

Undereating typically leads to decreased or plateaued athletic performance. This may mean decreased power, endurance, or strength. “If the body doesn't have a reserve of energy, it's going to need to pull that from the body. That means a breakdown of muscle and bone,” Blanton explains. Undereating also means the brain isn't working as well, so skills and rapid movement may be challenging. Lastly, recovery will be slower, so athletes will be sore longer and unable to perform at their best.

What is RED-S, and why should athletes care about it?

Relative energy deficiency in sport happens when a person isn't consuming enough nutrition to support their everyday activity and any additional physical activity. Athletes should care about RED-S because it can lead to impaired sports performance, longer recovery times, increased risk of injury, more frequent illnesses, bone loss, and other serious consequences.

How can athletes ensure they are eating enough?

If someone is concerned they may not be eating enough, working with a registered sports dietitian can help. They can help you understand what nutrients you need, how much you need, how those needs shift based on where you're at in your sports season (for example, pre-season versus before competitions), and what foods work best for you.

How can coaches and trainers support athletes struggling with undereating?

Coaches and trainers can do many things to support athletes struggling with undereating. Here are some practical suggestions:

1. If you're doing any weight monitoring, Blanton recommends reevaluating. “Do you need to do weight checks? Does the frequency need to be that high? Are you checking in on athletes to see how it's impacting them?” she asks. Then consider working with a HAES provider to find more effective ways to do all of this.

2. Focus on performance over weight metrics.

3. Limit negative food comments. Promote a food-first approach and encourage eating rather than discussing limitations on food, Blanton says.

4. Be mindful that eating disorders affect people of all shapes, sizes, ages, and genders, and athletes participating in any sport.

5. Have sports dietitians and other experts you can refer athletes to for additional support.