Relative Energy Deficiency in Sport (REDs): A Guide for Athletes

As an athlete, understanding your body and how it functions is crucial for optimizing performance and maintaining overall health. One significant issue that many athletes face is Relative Energy Deficiency in Sport (REDs). It is a syndrome with wide-ranging health consequences that can go unrecognized until significant damage has been done and is important for athletes to be aware of.

What is REDs?

REDs encompasses a spectrum of physiological, psychological, and performance impairments resulting from insufficient energy intake. This energy imbalance occurs when the energy consumed is insufficient relative to what is required for normal bodily functions and training demands. This leads to a state of low energy availability (LEA) and over time it compromises normal biological processes in order to sustain more critical functions.

We will review many of the side effects and symptoms of REDs later on in this article.

Who is at Risk?

REDs can affect any athlete, across all sports and genders. However, those in sports where weight ratios are critical such as runners, cyclists, and wrestlers are at a higher risk. Importantly, REDs is not limited to female athletes; male athletes can also experience the negative impacts of LEA, though these cases tend to be underdiagnosed and underreported.

Physiological Implications of REDs

Recognizing the signs of REDs is a vital step in addressing it. Here are some of the common physiological effects:

Gastrointestinal Distress

Many athletes report symptoms such as early satiety (feeling full quickly) and frequent bloating. This is due to delays in gastric emptying and intestinal transit, meaning food you consume goes through the digestive tract more slowly.

Cardiovascular Changes

Though often undetected, an energy deficit has a huge impact on the heart and body’s cardiovascular system. Decreased resting heart rate, lowered blood pressure, and electrolyte disturbances can occur, impairing overall performance. Untreated, these changes can also become dangerous, requiring immediate medical attention.

Nutritional Deficiencies

When food intake is inadequate, athletes aren’t just missing out on the energy in the food. They’re also missing out on meeting important  vitamin and mineral needs.LEA can lead to micronutrient deficiencies, particularly in iron and vitamin D, which are critical for energy metabolism and bone health.

Hormonal Imbalances 

When energy availability drops below what the body needs to support both training and basic physiological function, the brain downregulates reproduction to preserve more essential systems. In female athletes, this manifests as menstrual irregularities or complete loss of the menstrual cycle, known as Hypothalamic Amenorrhea (HA). Male athletes are equally vulnerable. Chronic LEA drives down testosterone production, resulting in reduced muscle mass, impaired recovery, low mood, and diminished training adaptations.

Sleep Disturbances

Athletes with REDs report disruptions in sleep, which may be due to the body being in a hypometabolic state, affecting nocturnal body temperature and sleep patterns. So even if athletes get 8 hours of sleep, they may not reach and sustain deep, restorative sleep, leaving them feeling unrefreshed.

Long-Term Effects of Chronic Under-Fueling

The effects of prolonged energy deficiency extend far beyond just effects to short-term performance.The long-term consequences of chronic under-fueling can be severe, and in some cases irreversible. This is of significant concern, particularly for young athletes who are still developing These include:

Decreased Bone Density and Increased Risk for Osteoporosis

Chronic LEA decreases bone immunity, an environment that favors bone resorption over bone formation. When this occurs during peak bone density accrual years, athletes may fail to achieve optimal peak bone mass. This significantly elevates their risk of stress fractures and early-onset osteoporosis later in life.

Impaired Growth and Development

Insufficient energy availability downregulates growth hormone signaling, which can cause deviations from expected growth trajectories. This can lead to delayed puberty and cause young athletes to fall off their growth curves, with potential long-term implications for skeletal and reproductive development.

Performance Decline

Although restrictive eating may appear to result in short-term performance gains, research consistently indicates that chronic LEA ultimately impairs neuromuscular function, reduces muscle protein synthesis, and compromises immune function. These outcomes collectively lead to declined both health and athletic output over time. 

How to Fuel Properly for Athletic Performance

Weight is just one of many variables that influence athletic performance. In most cases, it is not the most important one. A more effective and sustainable approach focuses on the following factors:

Building a strong nutritional foundation. 

Before turning to supplements or calorie tracking, athletes benefit most from establishing a consistent fueling base.We recommend using the Performance Plate Method to build this strong fueling foundation to ensure adequate energy and nutrient intake.

Increasing carbohydrate intake 

Carbohydrates are the primary fuel source for most athletic activity. In fact, research shows that there is a phenomenon called “low carbohydrate availability”, which can cause many of the same issues at LEA, even with adequate energy intake. Most athletes underestimate how much they need. Focus not only on carbohydrates pre- and post-training, but also consume a consistent amount throughout the day.

Prioritizing restorative sleep 

Sleep is one of the most powerful and underutilized recovery tools available to athletes. During deep sleep, the body releases growth hormone, repairs muscle tissue, and regulates appetite hormones. 

Maintaining consistent hydration

Even mild dehydration — as little as 2% body mass loss — has been shown to impair both physical and cognitive performance. Athletes should develop a hydration strategy during training and competition days rather than relying on thirst alone.

Conclusion

As an athlete, you must prioritize your health and well-being alongside your performance goals. Understanding REDs and its implications can help you make informed decisions about your nutrition and training, ultimately leading to a healthier and more successful athletic experience.

If you suspect you or someone you know may be experiencing REDs, consulting a sports medicine physician and registered sports dietitian is strongly encouraged. We specialize in helping female athletes work through REDs and LEA. If you’re feeling stuck or unsure about your fueling strategy, we invite you to apply for our Period Recovery Program. Together, we’ll focus on fueling your body, supporting your recovery, and getting your period back.