Understanding RED-S: Why Energy Balance Matters for Every Athlete

On this week’s NVDM Coaching team call, coaches Ashton George and McKenzie Doodian led an important conversation on a topic many endurance athletes overlook: Relative Energy Deficiency in Sport (RED-S).

More than just “low energy,” RED-S can impact nearly every system in the body and disrupt both health and performance.

Let’s break down what it is, why it matters, and how athletes can stay ahead of it.

What is RED-S?

Relative Energy Deficiency in Sport (RED-S) happens when your body isn’t getting enough energy from food to meet the demands of both training and daily life.

It’s not about body size or weight — and while it can overlap with disordered eating, the root issue is a chronic energy imbalance. Left unchecked, RED-S can lead to serious consequences across multiple systems:

Performance

• Slower race times

• Increased injury risk

• Reduced recovery between workouts

Hormonal Health

• Missed or irregular menstrual cycles

• Low testosterone in men

• Thyroid hormone disruptions

Bone Health

• Lower bone mineral density

• Higher risk of stress fractures

Mental Health

• Mood changes

• Brain fog

• Decreased motivation and increased burnout

Prevention Starts with Fueling

The best prevention strategy is simple: fuel consistently and intentionally.

Here’s what a balanced approach looks like:

Carbohydrates

The body’s primary fuel source for endurance activity and recovery.

Protein

Essential for muscle repair, recovery, and adaptation.

Healthy Fats

Critical for hormone regulation and long-term energy availability.

RED-S isn’t just caused by under-eating. Skipping meals, delaying post-workout nutrition, or managing high stress without increasing intake can all contribute to an energy gap — even in well-intentioned athletes.

Tools for Early Detection

You don’t have to wait for major symptoms to take action. These tools can help you and your coach identify RED-S before it escalates:

Blood Work

Regular panels tracking iron, vitamin D, thyroid function, and reproductive hormones.

Hormone Panels

Particularly useful if you’re experiencing irregular cycles, low libido, or persistent fatigue.

DEXA Scans

Helpful for assessing bone density and tracking changes in body composition over time.

These objective tools — combined with honest communication with your coach — offer a proactive path forward.

Key Takeaways for Endurance Athletes

• RED-S is about energy availability, not body image

• It impacts health, performance, and mental clarity

• Prioritize a mix of carbs, protein, and fats — especially around workouts

• Don’t restrict calories on rest days — your body still needs energy to repair

• Stay ahead of issues with regular blood work and scans

• Communicate early and often if you’re feeling unusually tired, moody, or unmotivated

Final Word

RED-S is preventable. At its core, it’s about ensuring your body has enough energy to support both your training and your life.

As Coach Ashton George said on the call:

“You train to get stronger — but that only happens if you give your body the fuel it needs.”

If you’ve been feeling “off,” dealing with unexplained fatigue, or just want to double-check your nutrition strategy, talk to your NVDM coach. We’re here to help you thrive — not just train.