What to Eat During a 24-Hour Race — Nutrition Strategy Guide

The Calorie Math

A runner covering 80-100 miles in 24 hours burns approximately 6,000-10,000 calories depending on body weight, pace, and conditions. You cannot — and should not try to — replace all of them.

The target: 200-300 calories per hour, starting from hour 1. This replaces 50-70% of expenditure. Your body's fat oxidation system covers the rest. Trying to eat more than 300 cal/hour risks GI distress, which costs far more time than the extra calories are worth.

Real Food vs Gels

The answer is both — but the ratio shifts as the race progresses.

Hours 1-8 (higher intensity): Gels, sports drink, and simple carbs dominate. Your digestive system is less efficient at higher effort, so easily absorbed sugar works best. Aim for a gel every 30-45 minutes plus sipping sports drink.

Hours 8-16 (moderate pace): Transition to real food. As pace slows, your stomach can handle more complex foods: boiled potatoes with salt, PB&J sandwiches, wraps with turkey, rice balls, banana slices, pretzels. Real food provides more satiety and psychological comfort.

Hours 16-24 (survival mode): Eat whatever sounds tolerable. Broth, flat cola, mashed potatoes, ramen noodles, watermelon. This is not the time for nutritional perfection — it's the time for calories in any form your stomach will accept.

Proven Real Food Options

• Boiled potatoes with salt — easily digestible, calorie-dense, the #1 ultra food worldwide
• PB&J sandwiches — balanced macros, familiar, easy to eat while walking
• Chicken broth/ramen — warm, salty, liquid calories when solids are rejected
• Watermelon — hydrating, easy on the stomach, natural sugars
• Pretzels — salt + carbs, won't melt or spoil
• Baby food pouches — seriously. Easy to consume, gentle on stomach, good variety

Hourly Fueling Plan

Notice the dip at hours 13-18: this is when GI issues peak. Don't force food. Even 150 cal/hour keeps you moving.

Hydration and Electrolytes

Dehydration and hyponatremia (over-hydration with sodium depletion) are both serious risks in 24-hour events.

• Drink to thirst as your baseline, then supplement with 16-24 oz per hour in moderate conditions
• Take 300-500mg sodium per hour via electrolyte capsules, salty food, or electrolyte drink
• Weigh yourself at 6-hour intervals if possible — aim to stay within 2-3% of starting weight
• Watch for warning signs: bloating and nausea can indicate both dehydration AND over-hydration

When Your Stomach Shuts Down

Somewhere between hour 10 and hour 16, most runners experience some degree of GI distress: nausea, bloating, loss of appetite, or active aversion to food. This is normal and manageable.

• Slow down or walk. Reduced intensity redirects blood flow to your digestive system.
• Switch to liquids. Broth, flat cola, diluted sports drink, smoothies.
• Eat tiny amounts frequently rather than trying to force a full serving.
• Ginger (chews, tea, or capsules) can help with nausea.
• Avoid fiber, fat, and dairy when your stomach is upset — stick to simple carbs.
• Wait it out. Most GI issues resolve within 1-3 hours if you manage them gently.

Caffeine Strategy

Caffeine is the most powerful legal performance enhancer in ultrarunning — but timing matters enormously.

• Avoid caffeine for the first 10 hours. You don't need it when you're fresh, and using it early builds tolerance.
• First dose: 10 PM — 100mg (one small coffee or caffeine pill). Preventive, before the low point hits.
• Second dose: 2-3 AM — 200mg. This is the rescue dose for the deepest circadian low.
• Third dose: 5-6 AM — 100mg optional. Helps bridge to dawn if still struggling.
• Total: 300-400mg over 8 hours. Enough to be effective, not enough to cause GI problems or jitters.

Night Nutrition

Your appetite and food preferences change dramatically at night. Plan for it:

• Warm food matters. Broth, soup, and warm rice feel completely different from cold sandwiches at 3 AM.
• Sweet fatigue is real. After 15 hours of gels and sports drink, your body craves salt. Have savory options ready.
• Familiar comfort food works. This is not the time for adventure eating. Bring the foods you know and love.

Common Mistakes

• Trying new foods on race day: If you didn't eat it in training, don't eat it in the race.
• Starting nutrition late: “I'll eat when I'm hungry” = calorie deficit by hour 6 and bonking by hour 10.
• All-gel nutrition: Your stomach will revolt against 24 hours of sugar gels. Plan real food from hour 6+.
• Ignoring sodium: Plain water without electrolytes leads to dangerous hyponatremia in long events.
• Using caffeine too early: Coffee at the start line wastes your best tool for the night.

Frequently Asked Questions