The 10 Most Common Nutrition Mistakes Endurance Athletes Make

You train hard. You follow your plan. But something's off — you're tired, plateaued, or getting injured more often.

The culprit might not be your training program. It might be your nutrition.

Endurance athletes consistently make the same nutrition mistakes that quietly sabotage performance. Let's break down the top 10 and how to fix them.

Underfueling — sometimes called RED-S (Relative Energy Deficiency in Sport) — is the silent performance killer.

When you consistently eat fewer calories than you burn, your body downregulates metabolism, hormones, and immune function. Performance suffers, injury risk rises, and recovery slows.

• Persistent fatigue despite adequate sleep
• Inability to maintain race weight
• Frequent injuries or illness
• Declining performance despite hard training
• Irregular periods (in female athletes)

Fix: Track your intake for one week and compare it to your training load. If you're consistently below 30 kcal/kg of body weight on high-training weeks, increase calories gradually.

Many athletes wait until they feel tired before eating during training. This is a mistake — by the time you feel fatigue, glycogen stores are already depleted.

The solution: start fueling within the first 30 minutes of any session over 90 minutes.

Drinking only water during long efforts dilutes blood sodium, increasing risk of hyponatremia and muscle cramps.

• Include 300–500 mg sodium per liter during exercise
• Add electrolytes to at least one bottle per long session
• Weigh yourself before and after to understand your sweat rate

The 60-minute window after training is prime time for glycogen restoration. Skipping it delays recovery by hours.

Target 1.0–1.2 g/kg carbs and 20–30 g protein within 60 minutes of finishing.

Protein isn't just for bodybuilders. Endurance athletes need 1.2–1.4 g/kg daily, distributed across 4–5 feedings for optimal muscle repair.

• Aim for 0.3–0.4 g/kg protein per meal (20–30 g for most athletes)
• Include protein in every meal and snack
• Prioritize high-quality sources: meat, dairy, eggs, soy, legumes

New gels, new drinks, new foods — race day is not the time for experimentation.

Everything you plan to eat or drink during a race should be tested in at least three long training sessions beforehand.

Eating too close to the start can cause gut distress. Eating too early means starting depleted.

The sweet spot: eat your pre-race meal 3–4 hours before the start, targeting 1–4 g carbs per kg.

Thirst is a late signal — by the time you feel it, you're already 1–2% dehydrated, which impairs performance.

Drink to thirst, but sip steadily throughout the day and during training rather than waiting for thirst signals.

Taper means reduced training volume, not reduced carb needs. Your body still needs fuel to absorb training adaptations.

Maintain carb intake while reducing volume — this is the time to top off glycogen stores, not deplete them.

What works for your training partner might not work for you. Sweat rate, gut tolerance, and carb needs vary significantly between athletes.

Don't copy professional athletes' nutrition strategies. Experiment to find what works for your unique body.

MAVR identifies and corrects nutrition mistakes automatically.

• Compares your intake against workout demands to flag underfueling
• Auto-schedules fueling timing to prevent glycogen depletion
• Adjusts hydration and electrolyte targets based on sweat rate
• Prompts post-workout recovery nutrition at the right time