What Is REDs? Everything You Need to Know About the Hidden Performance Killer That’s Draining Your Energy

“You’re training harder than ever but your body isn’t bouncing back. Let’s find out why.”

Table of Contents

What Exactly Is RED-S (and Why It Matters)

If you're an athlete feeling worn out, underperforming, or stuck in a plateau despite doing everything right, you might be dealing with RED-S: Relative Energy Deficiency in Sport.

No, this isn’t about being lazy or not trying hard enough.

RED-S is a metabolic and hormonal response to consistently having too little energy left over for your body to repair, recover, and thrive. It happens when your energy intake doesn’t match your training demands, and it’s more common than anyone likes to admit.

See full RED-S definition from the IOC →

Why Athletes Get It Wrong (Even When They're Doing Everything “Right”)

Many athletes assume performance is a product of training harder and eating “clean.”

But here’s the truth: you can eat plenty of food and still end up in RED-S if your body is burning more than you’re putting in, and you never truly recover.

RED-S is a whole system problem, not just a calorie issue.

Here’s why:

1. RED-S isn’t just under-eating, it’s under-recovering

You could be eating 3,000+ calories per day. But if your training volume and intensity push your body beyond its limits without proper recovery strategies, you’ll still fall into energy debt.

2. Stress, sleep, and hormones are part of the equation

Sleep deprivation increases cortisol (your stress hormone), which slows recovery and decreases muscle-building hormones like testosterone. Your body sees all stress the same — life stress, school stress, and gym stress all stack up.

3. Ignoring recovery metrics = major trap

Metrics like resting heart rate, HRV, and even mood or motivation are recovery warning signs. Most athletes don’t track them. They think “more effort” is always better. It’s not.

Why HRV matters for athletes →

Key Symptoms and Red Flags of RED-S

Not sure if RED-S might be affecting you? Start here.

🟠 You feel exhausted even after rest
🟠 You’re getting sick more often than usual
🟠 You’ve lost strength, explosiveness, or drive
🟠 Stress fractures or repeat injuries are showing up
🟠 Mood swings, low motivation, or brain fog
🟠 For females: missed periods or cycle changes
🟠 For males: reduced libido or low testosterone

If you nodded your head at 2 or more of these, it’s time to dig deeper.

More symptoms of RED-S via Children’s Hospital Boston →

The Science Behind It: RED-S and System Shutdown

Your body has a budget, and RED-S is what happens when you spend more than you earn.

In athletes, this often starts as:

• 🔺High-intensity training
  

• 🔻Not enough fuel or sleep
  

• ➡️Hormone disruption
  

• ❌Immune system crash
  

• 🚨Performance decline
  

This isn’t just theory. Here’s what real-world data shows:

• Up to 80% of athletes in high-demand sports have signs of RED-S

• Male athletes with RED-S often show low testosterone and high cortisol

• Athletes with RED-S face significantly higher rates of stress fractures and illness

Full RED-S prevalence study →
Hormone changes in male athletes →

What Recovery Really Takes: The Full Picture

RED-S isn’t fixed by eating a banana and hoping for the best. Real recovery requires a whole-system strategy that goes beyond food and reps.

✅ Advanced lab testing

• Look at iron, vitamin D, cortisol, testosterone, HRV, thyroid, and more

• Stop guessing about energy or hormone levels — test and know

✅ Sleep + stress load assessments

• Track sleep duration + quality

• Learn your personal “stress threshold” using metrics

✅ Precision nutrition - beyond macros

• Fuel based on testing, not fitness trends

• Restore energy balance and nutrient status strategically

✅ Recovery coaching and load management

• Periodized training plans to balance output and input

• Rest isn’t weakness, it’s performance insurance
  

Work with RPA Health to test your recovery →

Where to Learn More (and Get Help)

If you’re stuck, fatigued, and ready to stop guessing, Athlete Accelerator is built for you.

It’s not a cookie-cutter meal plan.

It’s a lab-guided, full-system performance plan that shows you exactly what’s wrong, why it’s happening, and how to fix it for good.

🧪 You get blood testing, nutrition insights, stress data, and recovery coaching all personalized
📈 We help you shift from energy debt into high-performance readiness
🤝 You’ll feel supported, not sold to

Click here to book your Strategy Session

Key Takeaways

✔️ RED-S is the hidden killer of athlete performance. You don’t need to be starving to be under-fueled.
✔️ Performance issues often start with a system breakdown, not a lack of hustle.
✔️ Most athletes ignore recovery signs until it’s too late.
✔️ The fix isn’t just more food or training tweaks, it’s a full picture view of your health.
✔️ Testing removes guesswork and gives you clarity.

Check out the full guide to the 4 Hidden Performance Killers

This free guide reveals the 4 hidden performance killers and how to fix them with functional sports nutrition and recovery science.

If your performance is dipping, your energy’s tanked, or you just know something’s off, don’t guess.

🔥 Book your Athlete Accelerator Strategy Session and get lab-based clarity on your recovery, hormones, and nutrition.

👉Book here