Trail running nutrition: the complete guide

In trail running, nutrition isn't a detail — it's the fourth pillar of performance alongside training, gear and mental strength. A bad fueling strategy can turn a well-prepared race into a nightmare. Here's everything you need to know.

The basics: what your body needs

During endurance exercise, your body burns two main fuels:

• Carbohydrates (muscle + liver glycogen): fast energy, but limited stores (~90 min of intense effort)
• Fats: slow and virtually unlimited energy, but less efficient at high intensity

The goal of race nutrition is simple: replace the carbs you burn to delay glycogen depletion (the infamous "wall").

Before the race: carb loading

D-3 to D-1: supercharging your stores

Increase your carb intake to 70% of calories: pasta, rice, bread, potatoes, fruit. Reduce fiber (no legumes, fewer raw vegetables) to avoid GI issues on race day.

Race morning

Eat 3 hours before the start. A meal you've tested in training:

• White bread or rice cakes + jam or honey
• 1 ripe banana
• Tea or coffee (careful, coffee is a diuretic)
• Optional: 1 applesauce pouch or plain yogurt

Avoid: eggs, butter, whole grains, orange juice (acidity).

During the race: km-by-km strategy

What to eat?

The choice between gels and solid food depends on intensity and duration:

Races < 2h (short trail): water + 1-2 gels is enough. Absorption is fast and the stomach isn't stressed.

Races 2-5h (medium trail): alternate gels and solid food. Plan for 200-300 kcal/h:

• 1 gel every 45 min (80-100 kcal each)
• Energy bars cut into pieces
• Dried fruit (dates, apricots), fruit paste
• At aid stations: banana, cheese, gingerbread

Races > 5h (ultra): solid food becomes essential as gels often cause nausea over long periods. Add salty options: chips, soup, ham, pretzels. Aim for 250-350 kcal/h.

When to eat?

Start eating within the first 30-45 minutes, even if you're not hungry. The stomach absorbs better when it's not empty. Then eat something small every 20-30 minutes.

Hydration: the other half of the equation

Dehydration of 2% body weight reduces performance by 10-20%. But drinking too much is also dangerous (hyponatremia).

How much to drink?

• Cool weather (< 15°C / 59°F): 400-500 ml/h
• Mild weather (15-25°C / 59-77°F): 500-700 ml/h
• Hot weather (> 25°C / 77°F): 700-1000 ml/h

Water, sports drink, or both?

For efforts > 1.5h, an isotonic drink (30-60 g carbs/L + sodium) is better than water alone. It provides energy AND electrolytes. Put it in one bladder and keep plain water in the other.

After the race: the recovery window

Within 30 minutes

This is the "metabolic window" when your body absorbs nutrients best:

• Recovery drink (carbs + protein, 3:1 ratio)
• Or: chocolate milk, banana-protein smoothie, yogurt + honey

Within 2 hours

Complete meal rich in carbs and protein: pasta with meat sauce, rice + chicken, or pizza. Yes, post-trail pizza is a classic for good reason.

The 4 fatal nutrition mistakes

1. Testing new nutrition on race day

Every gel, bar or drink must be tested in training. Your stomach needs time to adapt.

2. Eating only sweet food

Beyond 3h of effort, your palate tires of sweetness and your stomach protests. Plan for salty options.

3. Not eating on climbs

Power-hiked climbs are the perfect time to eat — intensity is lower and the stomach works better.

4. Waiting until you're hungry

Hunger during a race is a late signal. By the time you feel it, your glycogen stores are already in freefall.

Plan your nutrition with RaceDayLab

Our Fuel Planner automatically calculates your calorie, hydration and fueling needs based on your race, speed and weather conditions.