RED-S in Young Female Athletes: What You Need to Know

Picture this: a high school athlete pushing hard in practice, skipping meals, and battling fatigue. She’s missing periods, nursing a stress fracture, and no one knows why. This is RED-S—Relative Energy Deficiency in Sport—and it’s more common than you think, especially in young female athletes.

What Is RED-S

RED-S happens when an athlete isn’t eating enough to fuel both their sport and their basic body functions. It goes beyond the old “Female Athlete Triad” and impacts every system: hormonal, cardiovascular, immune, and more. This isn’t just about food—it’s about health, performance, and long-term well-being.

Young female athletes are uniquely vulnerable to RED-S due to a combination of physical demands and external pressures. During adolescence, their bodies are not only training hard but also growing rapidly, which increases the overall energy requirement. When these energy needs aren’t met—whether due to intentional restriction or simply not realizing how much fuel is needed—it can lead to low energy availability. Social and cultural pressures to stay lean, achieve a certain body image, or “eat clean” can also contribute. Many athletes, parents, and even coaches mistakenly believe that missing or irregular periods are normal for athletes. In reality, menstrual dysfunction is a key warning sign that the body isn’t getting what it needs.

How RED-S Shows Up

The effects of RED-S ripple across nearly every system in the body—and as a physical therapist, I see the consequences in orthopedic injuries, pelvic floor health, and overall performance.

From an orthopedic perspective, RED-S often presents as recurring stress fractures, slow-healing injuries, and persistent joint or tendon pain. Without adequate fuel, the body can't repair or rebuild tissue efficiently, leaving athletes more susceptible to breakdown.

In terms of pelvic health, menstrual dysfunction is a major indicator. Hormonal imbalances can lead to pelvic instability or pain and may negatively impact connective tissue quality, which is essential for injury prevention and core control.

When it comes to sports performance, the red flags are often masked as “working hard” or “pushing through.” But, poor recovery, decreased strength and endurance, irritability, and emotional burnout are common. These athletes often feel like they're doing everything right—but their performance continues to decline.

Signs to Watch For

If you're working with a young female athlete—or parenting or coaching one—pay close attention to these common signs. Missing or irregular periods are one of the biggest red flags and should never be brushed off as normal. Chronic fatigue, dizziness, or lightheadedness, especially during or after training, may indicate low energy availability. Frequent injuries that don’t seem to heal properly, anxiety around food or body image, and declining performance despite intense training are all warning signs that shouldn’t be ignored.

What You Can Do as a PT, Coach, or Parent

One of the most impactful things we can do is prioritize health over aesthetics or weight. It's essential to shift the focus from how an athlete looks to how they feel, perform, and recover. Teaching young athletes that their bodies are powerful tools—not objects to be judged—can be a game-changer.

We should also celebrate fueling, sleep, and strength, rather than restriction, overtraining, or pushing through exhaustion. Encouraging adequate nutrition and rest not only supports performance but also reinforces the message that self-care is part of being an elite athlete—not a weakness.

Finally, it’s important to foster open, judgment-free conversations about body image, stress, menstrual health, and training demands. When athletes feel safe talking about these things, we’re far more likely to catch warning signs early and support long-term health and success—on and off the field.

The Road to Recovery

• Eat more. Rest more. Period.

• Rebuild from the inside out—bone, hormone, muscle, mood.

• You can’t perform at your best if your body’s in survival mode.

  
  

Final Thoughts

RED-S isn’t rare. It’s just underrecognized. If an athlete isn’t menstruating, constantly injured, or running on fumes, it’s a red flag—not a badge of honor. Recovery is possible, and it starts with awareness.