You're training hard, but your performance has plateaued? Struggling to recover after intense sessions? Dealing with recurring tendinitis, digestive issues, or chronic fatigue? You’re not alone.

After conducting over 150 interviews with nutritionists and elite athletes, David Nicolas, founder of the brand Féroce and host of the Limitless Project podcast, identified the 4 diet mistakes that destroy athletic health and performance.

Mistake 1: The Modern Eater’s Paradox

Exercise is a stressor. It creates a temporary state of imbalance — your body then needs to recover and overcompensate in order to come back stronger. But here’s the catch: this rebuilding process requires real nutrients.

And yet, despite eating more than ever in human history... we’re more nutrient-deficient than ever.

Why? Because of empty calories and ultra-processed foods: additives, preservatives, emulsifiers, refined sugars, bad fats (too many omega-6s), and modern gluten.

Result: Your digestive system gets attacked when it should be nourished. You weaken your body instead of helping it rebuild.

Mistake 2: The Athlete’s Invisible Inflammation

Training creates inflammation — that’s normal. But it should then be regulated, especially by anti-inflammatory omega-3s.

The problem? Our modern diet contains too many pro-inflammatory omega-6s, and not enough anti-inflammatory omega-3s. To put it simply: the “firefighters” are missing.

Result: Instead of following the healthy cycle — Effort → Recovery → Supercompensation — you fall into a vicious cycle — Effort → Irritation → Burnout.

Mistake 3: The Breakdown of the Gut Barrier

Your gut is an intelligent filter — it lets in the good stuff and blocks out harmful molecules.

But chronic stress, antibiotics, modern gluten, additives, and emulsifiers damage this filter.

Result: You absorb fewer vitamins and minerals. And worse — unwanted fragments pass through, triggering immune responses, inflammation, and fatigue.

This leads to digestive issues, lowered focus, and reduced resilience.

Mistake 4: Massive Micronutrient Deficiencies

Not only does our modern diet lack essential nutrients — but our bodies are less and less able to absorb what little we do get.

The result? Up to 75% of adults are deficient in magnesium, vitamin D, iron, zinc, calcium, vitamins B9 and B12… not to mention key amino acids like L-carnitine or glycine.

Yet these are the building blocks of your cells, hormones, neurotransmitters, and enzymes.

When you’re deficient, your body prioritizes short-term survival over long-term performance and health.

Bottom line: You’re holding yourself back instead of accelerating your progress.

The Secret: Nutrient Density

If you want to perform — in sport and in life — you need to base your diet on nutrient density.

That’s the foundation of the Féroce Pyramid.

Want to learn how to do it right? Download the Ultimate Guide to Sports Nutrition — available for free here.