Gymnasts and RED-S are unfortunately linked more often than parents realize. RED-S, otherwise known as relative energy deficiency in sport, is a syndrome introduced in 2014 by the International Olympic Committee to expand upon the female athlete triad. This was necessary, as the well-known “female athlete triad” is limited to females with stress fractures, amenorrhea (no period), and eating disorders. It misses a huge population of male and female athletes that are suffering from under-fueling. RED-S has expanded the qualifications needed for diagnosis of low energy availability and aids in earlier identification and treatment.

History of The Female Athlete Triad and RED-S

The female athlete triad has three specific categories one must fit in to be diagnosed with this condition. 

  1. Amenorrhea or the absence of one’s period
  2. Disordered eating
  3. Stress fractures

This constellation of symptoms started to grow in the scientific literature in the 1980s. Researchers focused on looking at dancers and the relation between fractures, delayed puberty, and amenorrhea.  

When a female is not eating enough to compensate for daily energy needs (including high levels of exercise for elite athletes), the hypothalamus of the brain tells the ovaries to “shut it down”. Hormone production (that fuels the menstrual cycle) comes to a halt as it senses there isn’t enough energy available to support a baby.  

Not only is the menstrual cycle and sexual development affected, but there is also a loss of estrogen. This drop in hormone production leads to a loss of bone mass, and thus, an increased risk of stress reaction and stress fracture.  

There is a high incidence of disordered eating and eating disorders, which leads to inadequate energy intake. However, one does not have to have disordered eating to be “unintentionally under fueling” and have the same physical effects as that of the female athlete triad.  

Introduction of RED-S

This is why the International Olympic Committee introduced the concept of RED-S  in 2014.

It’s a way to describe the physical and psychological effects of inadequate energy intake on athletes. It creates the space to erase the previous limitations of females with disordered eating, amenorrhea, and stress fractures. After all, these are only a few of the symptoms of inadequate energy availability.  

Males and females both can suffer from under-fueling. This is extremely important considering males were not capable of being diagnosed with any issue. The triad was for females only.  

To diagnose RED-S, a calculation is done that takes into account an athlete’s energy intake minus exercise energy expenditure per kilogram of fat free mass. The literature supports that a minimum of 45 kcal/kg fat free mass is required for normal physiological function and training recovery/adaptation.  

When a gymnast is eating below 30 kcal/kg fat free mass, they will begin to see physiological consequences such as:  

  • downregulation of the metabolism  
  • reproductive hormones  
  • thyroid hormones  
  • impaired muscle growth  
  • adaptation  
  • increased cortisol (stress hormone)  
  • decreased immune function

Many gymnasts have RED-S. They simply are not taught from a young age how much energy they need to fuel 20+ hours a week of training.  

It’s important to review in depth the ramifications of RED-S. Awareness and early identification can help improve performance, recovery, and longevity in the sport.  

Gymnast Relative Energy Deficiency in Sport


Inadequate energy availability will lead to either primary or secondary amenorrhea. Primary amenorrhea is characterized by no period by 15 years old. Secondary amenorrhea is the loss of the period for more than 3 months after the first year of menstruation.  

When the brain senses there is not enough energy available to support a baby, the hypothalamus down regulates the production of gonadotropin releasing hormone. Once this hormone is released, it stimulates the ovaries to produce estrogen and progesterone.  

This initially leads to irregular periods and then complete cessation of them all together if the energy deficit is not resolved. Inadequate nutrition is one of the main reasons many gymnasts do not get their period until they are 16,17, or 18. Or not until after they retire from the sport. Although they are told it is normal, it is most definitely NOT normal to get a period that late. This can lead to serious health ramifications that will jeopardize an athlete’s career and must be resolved.  

On occasion, some gymnasts are “genetically normal” to not start their period until age 15 or 16. However, this is rare. An athlete should first look at family history and see at what age the females started their periods. Keep in mind though, it’s very common for mothers of gymnasts to also have been athletes or former gymnasts. This means it is quite likely they were under-fueling if they didn’t start their period until after 15. Take for example the gymnasts whose family has a trend of starting their periods around age 11. If the athlete is showing no signs of puberty at age 14, there is a pretty high chance that this is caused by under-fueling or the gymnast has RED-S.  

Bone Health

Another organ system that gets disrupted when under-fueling occurs is loss of bone regeneration and repair. When a gymnast does not get her period, the level of estrogen is too low which actually causes bone loss. This is one of the main reasons stress fractures are a huge problem in gymnastics. The athlete does not have enough energy to build or maintain bone mass.  

Doctors and physical therapists often think it is just a regular stress fracture. But for this specific population of athletes, most stress fractures in gymnasts are due to RED-S, not overuse or a freak accident. This is why it is beneficial to correct the under-fueling in the gymnasts to help them be able to recover after training and minimize injuries.  

Putting a gymnast on oral contraceptives that contain estrogen will not protect the bones. The hormones are metabolized sooner at the liver than the endogenously produced hormone. Many high-level gymnasts have a false reassurance of their “health” because they’re on oral contraceptives. Which masks under-fueling by way of monitoring the menstrual cycle. The monthly “period” from some forms of birth control is not a real ovulatory period. It’s just a “withdrawal” bleed that occurs in response to a drastic drop in estrogen and progesterone.  

When a gymnast continues to train with RED-S, she will continue to lose bone mass and is at greater risk of injury. The only way to correct and reverse the bone loss (which is not always reversible) is a resolution of inadequate energy availability, along with adequate calcium and vitamin D.  

Metabolic Changes

The often-overlooked aspect of under-fueling is the negative metabolic adaptions that occur. This can negatively affect body composition as well as unintentionally reducing food intake to control weight and shape.  

When not enough fuel is given to the body, it is going to do everything it can to conserve the energy that is being put into it. Often body temperature decreases because the calories need to be conserved for more important purposes like keeping their vital organs alive.  

Major red flags that a gymnast may be suffering or on their way to developing RED-S are:

  • bruising in the skin
  • hair loss
  • fatigue
  • exhaustion even after sleeping for many hours

The literature reports that some gymnasts with RED-S lose weight and body fat. Whereas others will lose muscle and increase fat mass. Even for those who lose weight and body fat, which may seem preferable, this won’t be sustainable for long-term health or performance.  

Starvation Mode?

Many people may have heard of “starvation mode”. Many diet gurus and personal trainers will blame individuals “mysterious weight gain” while dieting on what they call “starvation mode”. Otherwise defined as eating so little that the body stores everything as fat. This is most definitely not true, and quite an out-of-context term. However, it is true that when our bodies are not receiving the nutrients they need that they will metabolically adapt to function at that energy level. The metabolism will slow down in response to inadequate food intake and can lead to muscle loss and negative changes in body composition.  

Fear of gaining weight

Most gymnasts are convinced that if they eat “more” or enough to fuel their workouts, they will gain massive amounts of weight. Since there are not adequate amounts of energy going into the athlete, their bodies have turned many systems down to conserve the little amount of energy they are receiving. However, the body is pretty amazing. Once enough energy is put into it, the body begins to metabolically adapt by speeding up the metabolism to process all of this new fuel.  

Big picture, this is the reason why the myth, that when a person eats more they will automatically weigh more, is NOT TRUE.  

Athletes I have worked with to increase their calorie intake significantly and often do not gain weight (or don’t gain massive amounts of body fat). It’s simply because their body’s metabolism knows exactly how to process and use the new energy it has been given.  

This is not true in every situation. But if a high-level gymnast is really under fueling, then an appropriate increase in food intake will only benefit their training and performance. If they do gain weight during this process, this was likely just normal and necessary weight gain (muscle and fat) for proper growth and development.  

Growth and Developement

Monitoring a gymnast’s growth patterns, for weight and height, by looking at their growth curve with their pediatrician is the best way to see if RED-S should be on the radar. BMI should not be taken into consideration because it is flawed. It is not made for adolescents and can shift radically with just slight changes in weight or height. Over analyzing this number can often cause more concern than it informs.  

Every athlete is unique. For some, tracking in the 80th percentile for weight is completely normal. And for others, the 25th percentile is normal. The red flag is when the gymnast starts to fall off of her own curve. Say an athlete tracked in the 50-70th percentile for weight from age 7-10. Then her weight steadily or rapidly plummeted to the 25th percentile once training hours and body insecurities increased. This is where concern arises. This is why it is important to monitor athletes’ growth charts closely as it highlights when the under-fueling began.  

Hematological System (Blood)

Iron deficiency with or without anemia is another common downstream consequence of RED-S, especially in athletes. This condition can severely affect performance as iron insufficiency and deficiency can cause symptoms of:  

  • fatigue
  • shortness of breath
  • dizziness
  • increased perceived exertion

This last side effect known as increased perceived exertion is when everything feels more difficult than it should. This is a red flag for anemia. Therefore, if a gymnast does not eat a lot of red meat/fortified grains or has a very heavy period, it is important to monitor their iron levels with their pediatrician. Even if they do eat red meat a few times a week along with fortified grains, it’s recommended to check the iron status in athletes at least once a year.  

There are four stages to iron deficiency. The first two stages show a decrease in serum ferritin (a measure of iron stores) and physical effects like fatigue, shortness of breath, dizziness, and poor recovery.  

Stage 3 of iron deficiency is characterized by tissue iron depletion and decreased blood production with an increase in serum transferrin receptors.  

Stage 4 of iron deficiency is where there are decreases in ferritin, blood hemoglobin, hematocrit, and increased transferrin saturation. This leads to a diagnosis of anemia, specifically iron deficiency anemia, which needs to be treated with supplemental iron under the monitoring of a physician or dietitian.  


RED-S is a major contributor to psychological dysfunction, but unfortunately, many athletes’ anxiety, depression, and moodiness are often attributed to their age.  

Teenage angst may not be the sole cause of the athlete’s moodiness. Instead, it could be a sign of under-fueling. Let’s look at the behind-the-scenes of why this happens. Brains need 130 g of carbohydrates each day to function. That’s more than 8 slices of bread. When it does not receive that energy, it is incapable of dealing with mood and emotional regulation. This under-fueling often leads to overly emotionally gymnasts during practices and meets. As a gymnast myself, for me this looked like consistently crying on bars every day when I had RED-S. At the time, I didn’t know this was a symptom of being under-fueled.  

If the gymnast is exhibiting any of these symptoms or mood changes, it’s important to have their energy availability assessed. Plus, appropriate referrals are made to a therapist if indicated, as there may be other issues at play besides under-fueling.  

Heart, Gastrointestinal System, and Immune System

All three of these body systems can be severely affected by a gymnast under fueling. When athletes are significantly under-fueled, getting their heart checked is essential to ensure their safety. Whether that means getting an EKG or doing the walk test, they are both necessary to keep the athlete safe.

The “walk test” was created by an eating disorder physician to tell the difference between an athletic heart and a sick heart. It’s very common for athletes to be complemented by medical providers for low resting heart rate and blood pressure. It’s often assumed these are low due to the athlete’s high level of fitness. However, there is a difference between a low heart rate that stays low upon exertion and a heart rate in a malnourished athlete that is low at resting and jumps up during exertion. This spike in heart rate is caused by the heart having to work overtime because it is weak and atrophied. Which places this athlete at risk of significant heart complications if left untreated.

Gastrointestinal System

In the gastrointestinal system, bloating and constipation are common symptoms of under-fueling due to delayed transit. Take a gymnast who is pretty “regular” in terms of bowel movements for example. If she starts complaining about being bloated and/or constipated after an increase in practice time and a decrease in nutrition, a food intolerance test is unnecessary. In some cases, yes, there could be a food intolerance on top of malnutrition. However, it is almost guaranteed that her lack of bowel movements is caused by RED-S. The intestines and the stomach are all muscles. When under-fueling occurs, these muscles atrophy to provide energy for the body. This atrophy leaves the athlete with constipation and other GI issues that nine times out of ten go away once nutrition is restored.  

That being said many doctors do gymnasts a disservice because they search and search for answers through doing scopes and blood work. But they never think to refer them to a dietitian to see if they are eating enough. Or, they refer them to a dietitian for an “elimination diet”. This change in diet is used to figure out if food intolerances are causing the GI symptoms. In reality, this diet often just exacerbates the issues due to it being inadequate in energy.  

Immune System

Being that we have been in a pandemic, our immune systems are extremely important right now. But if the athlete is under-fueling, that protective barrier is going to be weakened. Often gymnasts will present with symptoms of what seems like just a cough. However, due to their diminished immune system, it can quickly turn into an upper respiratory infection. Under-fueling does not allow for the gymnast’s immune system to fight off infections well. And is one main reason why small colds turn into greater illnesses.  

Obviously, there is a difference between catching a small cold and it going away in a few days to when the sickness keeps reoccurring or getting re-infected. Yet, in meet season it would be unfortunate for the athlete to have to miss out on competing because they are sick due to under-fueling. Adequately fueling an athlete’s body is the NUMBER 1 WAY to protect their body. No matter the amount of fruit, vegetables, or superfoods the athlete intakes is the answer. Ultimately, correcting malnutrition is what will help them the most.  


A classic symptom of RED-S is decreased endurance. This can look like the gymnast not being able to get through a floor routine due to sheer exhaustion. Of course the athlete is exhausted. Their body does not have the energy it needs to complete a floor routine. And this could be the potential cause of our next symptom, which is increased injury. It is very common to see athletes with stress fractures and stress reactions throughout their bodies. However, this symptom even applies to previous injuries not being able to heal properly or as quickly as they should.  

Decreased training response is another symptom that is similar to decreased endurance. It highlights the reason that gymnasts have such a hard time getting their skills back once they hit puberty. It is because they are so under-fueled. A few other symptoms are:  

  • decreased coordination  
  • impaired judgment  
  • decrease in concentration  
  • increase in irritability  
  • depression.  

Again, all of these signs of RED-S are often seen as signals of the teenager angst phase. But in reality, could all be due to under-fueling.  

Decreased muscle strength is another area that plummets when an athlete has RED-S. It is much harder to get skills back or to build strength. Leading many parents and coaches to not understand why their gymnast is not getting stronger when they are putting in the work. And yes, the athlete is putting in the work. But no matter how much work they put into training, they are still not going to be able to gain all that strength back due to a lack of proper nutrition.  

What to do Next?

What if your gymnast is showing some or all of the symptoms of RED-S? First off, I would say it never hurts to get a nutrition analysis done by a dietitian. A dietitian can analyze your gymnast’s food intake, training, growth charts, and see how they are all intertwined. There are so many factors needed to be taken into consideration when assessing nutrition status.  

It’s important to note that an athlete can be under fueled AT ANY WEIGHT. This is one reason why I firmly believe that working with a team of clinicians is necessary to create a diagnosis. And why I work directly with my clients’ pediatrician, therapist, physical therapist, and/or orthopedist.  

Once you find a dietitian, they will guide you in beginning to plan meals and snacks that will slowly increase the amount of energy going into the body. I know the “elephant in the room” is weight gain, but this is just not something we can predict. Some athletes gain weight, lose weight, or stay the same when RED-S is resolved. For older adolescent athletes, it’s not uncommon for body composition to improve once adequately fueled. Quite the opposite of what most athletes expect of “eating more”. This is an education piece I use constantly to help my clients to trust me and their bodies. That increasing their fuel intake will actually help them in the long run.  

After all of this being said, the main goal is to get your gymnast back to health so they can perform their best and be safe doing gymnastics. Trusting the process of increasing food intake is super scary. But it is the only way to resolve RED-S and get them back to full strength in the gym and doing what they love.  


In summary, RED-S is a syndrome that is caused by a lack of energy availability.  

Here are some of the main systems that it may affect in an athlete:

  • Hormonal: menstrual cycle and mood
  • Skeletal: bone health, growth and development, muscle atrophy
  • Psychological: mood
  • Cardiac: low heart rate
  • Hematological: anemia
  • Gastrointestinal: constipation and other issues
  • Immune System: weakened immune function

What signs can be monitored in gymnasts as evidence of RED-S?

  • Decreased endurance
  • Increase in injuries
  • Decreased training response
  • Decreased coordination
  • Impaired judgment
  • Decrease in concentration
  • Increase in irritability and depression
  • Decreased muscle strength

What if you suspect that the gymnast has RED-S?  

  • Speak to a dietitian that will communicate with the gymnast’s outside doctors/providers  
  • Follow the dietitian’s plan as far as increasing fuel  
  • Set up a supportive circle of people for the athlete because recovering from RED-S is not only physically hard but also emotionally difficult too.  

As a dietitian, it is my goal to help gymnasts heal their bodies and relationship with food first and foremost. Once their bodies are healed and the brain follows, it will allow them to get back into the gym and participate in the sport they love. Recovering from RED-S is not always easy. Yet it is so rewarding when the athlete gets to return to their peak performance level out on the floor. A gymnast will not reach their full potential in the gym if they are suffering from RED-S.  

If you have any further questions or you would like to schedule a discovery call, please feel free to contact me!