The Medical Condition Affecting Swimmers You’ve Never Heard of: Relative Energy Deficiency In Sport (REDs)

Courtesy: Katherine Bell Hill, MD

I often get asked what the number one nutritional deficiency is in competitive athletes like swimmers. Protein? Iron? Vitamins?

No. By far, the number one nutritional deficiency I see in competitive swimmers in my medical practice is a deficiency of calories. While often our society considers the word “Calorie” to be a bad word, swimmers cannot fall victim to this mindset.

A calorie is, by definition, a unit of energy. And swimmers need to think of calories as their energy that will fuel their training and performance, rather than something to limit or avoid.

Why is it so hard for swimmers to meet their caloric needs? There are several factors that impact how many calories an individual needs:

• Basal Metabolic Rate: energy needed to keep your basic functions going
• Thermic effect of food: energy needed to digest
• Physical Activity Level
• Times of growth
• Muscle mass
• Cold environments
• Recovery from illness, injury, or post-workout

For competitive swimmers who are actively training, most fall into the high physical activity level category. Many are in a life stage of growth and/or are trying to build or maintain muscle mass. Swimmers spend hours trying to maintain body temperature in cold pools, and their bodies are constantly trying to recover from workouts. By all equations, swimmers tend to have uniquely high energy needs compared to most humans on earth. Swimmers tend to be ambitious, busy people too: rushing from morning practice to school or work, and often back to the pool again later in the day. Logistically, getting enough nutrition can be a real challenge.

When an athlete is underfueling, over time they tip into a metabolic state called Low energy availability (LEA). If the state of  low energy availability persists, an athlete can develop a medical condition called Relative Energy Deficiency in Sport (or REDs), which can lead to a myriad of health and performance challenges that we’ll review below.

I stay up to date on health issues affecting athletes. Why haven’t I heard of REDs?

REDs has been around as long as there have been training athletes, but the condition was first described in 2014 by a team of experts at the International Olympic Committee, with an updated consensus statement by the IOC released most recently in 2023. Prior to that, the condition was known as the Female Athlete Triad or Male Athlete Triad, which consisted of the 1) inadequate calories, 2) suppressed hormones (and missing/absent periods in females), 3) and decreased bone density. The REDs framework is more inclusive of all the medical and performance complications that are seen, as REDs can affect virtually every organ system in the body. Despite being really common in swimmers, many athletes and coaches don’t yet know about it, so there is also an awareness gap.

Is REDs really that common in swimmers?

As REDs is a newer condition, we still need more research to better quantify the true prevalence in swimmers. But the available research consistently shows that competitive swimmers are at a particularly high risk for REDs given the high energy demands of swim training. For instance, a study of NCAA Division III swimmers showed 43% were in a state of low energy availability. Another recent study of elite collegiate swimmers found almost none met their nutritional requirements during intense training.

What are some of the warning signs of REDs?

If you or your athlete are consistently underfueling, you might notice some of the following warning signs:

• Fatigue or poor recovery after workouts
• Decreased athletic performance
• Low testosterone in males (decreased libido, difficulty maintaining muscle mass)
• Missing or absent periods in females over 15
• Slowed resting heart rate (which isn’t always due to “fitness”)
• Increased risk of injury
• Feeling dizzy when standing up
• GI symptoms (constipation, fullness/bloating after meals)
• Preoccupation with “clean” eating and/or a reliance on supplements
• Feeling unusually cold, particularly in the hands and feet
• Changes in mood, like feeling more down or sad
• In growing kids and teens, dropping in height, weight, or BMI percentiles on growth charts

Wait, I thought it was normal for female swimmers to not get periods.

This is a popular myth that has been perpetuated, likely because missing periods are so common in female athletes that often they believe it’s normal. If you or your swimmer is a female over the age of 15 and is not getting regular monthly periods, this is not normal and warrants a medical evaluation, which often leads to a diagnosis of REDs.

I’m a male swimmer. This doesn’t affect me, right?

Actually, REDs is super common in male athletes as well.  In fact, growing male competitive swimmers have some of the highest caloric requirements ever recorded! Male athletes who underfuel tend to have low testosterone levels. And to perform at your best, you do need your body to produce enough testosterone on its own.

I think I may have REDs. How do I know for sure and how is it treated?

REDs is a medical diagnosis, and typically requires a medical evaluation to know for sure. Often blood tests are needed to check things like your blood count, kidney/liver function, hormones, iron stores, and vitamin levels. It’s typically treated by working with a REDs-savvy Registered Dietitian to make sure you’re getting in enough calories and overall nutrients. Sometimes, there are medical complications that need to be managed by a medical provider as well, like low heart rate, bone stress injuries, or low hormone levels.

Have another question about REDs?

Comment below or email Dr. Hill at [email protected].

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. If you or someone you know is struggling with REDs or an eating disorder, please seek help from a qualified healthcare provider.

REDs Resources:

• Project REDs
• Lane 9 Project
• 2023 IOC’s Consensus Statement on Relative Energy Deficiency in Sport (REDs)

Katherine Bell Hill, MD is a Stanford-trained physician, former Stanford swimmer, and Founder/Medical Director of AthleatMD. She was formerly the lead physician at Equip Health, the nation’s leading virtual eating disorder treatment program. She is passionate about educating anyone who will listen on health issues impacting athletes, particularly on REDs and other fueling concerns.