A female athlete can work hard, eat nutritious foods, and still not consume enough energy to support everything her body is being asked to do.

Her body needs energy for practice and competition, but it also needs energy for growth, recovery, bone health, menstrual function, concentration, immune function, and everyday life. When the energy available to the body remains too low, health and performance can begin to change.

This is the foundation of Relative Energy Deficiency in Sport, commonly called RED-S or REDs.

What Is RED-S?

RED-S is a syndrome associated with problematic low energy availability. Low energy availability occurs when the energy left after exercise is not sufficient to support the body’s other essential functions.

This can happen intentionally, but it is often unintentional. An athlete may underestimate how much fuel she needs, miss meals because of school and practice, add extra training without adding food, or follow nutrition advice that does not account for growth and sport demands.

An athlete does not have to look underweight, lose a specific amount of weight, or have an eating disorder to experience low energy availability.

How Is the Female Athlete Triad Related?

The Female Athlete Triad describes the relationship among low energy availability—with or without disordered eating—menstrual dysfunction, and impaired bone health. RED-S is a broader framework that recognizes that low energy availability can affect many systems and athletes of any gender.

The two frameworks are related, but neither should be reduced to a simple checklist. Athletes may experience different signs, and those signs can exist across a spectrum.

What Signs Deserve Attention?

One symptom does not automatically mean an athlete has RED-S. Patterns and changes are what matter.

• Persistent fatigue or difficulty recovering
• A decline in performance despite continued training
• Frequent illness
• Repeated bone-stress injuries or other recurring injuries
• Missed, irregular, or changed menstrual periods
• Difficulty concentrating, irritability, or changes in mood
• Feeling unusually cold
• Changes in sleep
• Ongoing food restriction or anxiety around eating
• Weight or body-composition changes

Some athletes using hormonal contraception may not be able to use bleeding patterns as a clear indicator, which is one reason the complete health and training picture matters.

Under-Fueling Is Not a Character Flaw

RED-S should never be framed as a lack of discipline. In many sports, athletes are praised for doing more, eating less, or changing their bodies. Young athletes may receive conflicting messages from coaches, teammates, social media, and adults they trust.

Sometimes the problem is simply logistics: early school, long classes, travel, late practices, limited food options, or no time to eat between activities.

The goal is not to blame the athlete. The goal is to recognize what her body is communicating and help her access support.

What Can Athletes Do?

• Eat consistently across the day rather than waiting until hunger becomes extreme.
• Add fuel when training volume or intensity increases.
• Tell a trusted adult about persistent fatigue, menstrual changes, pain, or declining performance.
• Avoid making major food or supplement changes based only on social media.
• Remember that rest and fueling are parts of training.

How Parents and Coaches Can Help

Parents and coaches are not expected to diagnose RED-S. They can notice changes, create a supportive environment, and help the athlete connect with qualified professionals.

• Focus conversations on health, energy, recovery, and performance—not appearance.
• Avoid praising weight loss or promoting one “ideal” athletic body.
• Normalize meals, snacks, rest days, and menstrual-health conversations.
• Take persistent pain, fatigue, and menstrual changes seriously.
• Coordinate support rather than placing the responsibility entirely on the athlete.

Who Should Be Part of the Support Team?

Evaluation and recovery may involve a physician or pediatrician, sports dietitian, athletic trainer, physical therapist, and mental-health professional. The right combination depends on the athlete’s symptoms and circumstances.

No single professional has to manage every part alone. The best support is collaborative, athlete-centered, and free of shame.

Health Supports Performance

An athlete should not have to choose between being healthy and being competitive. Adequate energy availability supports the training adaptations athletes work so hard to achieve.

Learning about RED-S is not meant to make athletes fearful. It gives athletes, parents, and coaches language for recognizing concerns earlier and creating an environment in which asking for help is a strength.

This article is educational and is not a diagnosis or individualized medical or nutrition advice. Athletes with persistent symptoms should be evaluated by qualified healthcare professionals.

Evidence resource: 2023 IOC Consensus Statement on REDs