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

The Calorie Math

Energy expenditure during a 24-hour race depends on distance, body size, efficiency, terrain, weather, and pace. Intake also varies because gastric emptying, appetite, food access, and tolerance change through the event. A precise 24-hour calorie deficit cannot be predicted from duration alone.

The International Society of Sports Nutrition position stand suggests a broad race-intake range of 150–400 kcal per hour, including roughly 30–50 g carbohydrate and 5–10 g protein per hour. Treat that as a research-informed starting range, not a prescription: build gradually in training and adjust to effort, conditions, and symptoms.

Real Food vs Gels

The answer can be either or both. The useful ratio is the one you have tested.

At higher effort: Small portions of carbohydrate drink, gels, chews, or other familiar low-fiber foods may be easier to dose and tolerate. Do not assume a gel interval that you have not practiced.

As pace and appetite change: Familiar foods such as potatoes, sandwiches, rice, bananas, pretzels, or broth can add variety. Solid food is not automatically easier later, so keep more than one tested texture available.

When taste fatigue develops: Rotate sweet, neutral, and savory options. "Whatever works" should still mean food and drink that have been tested for ingredients, concentration, and portion size.

Food Options to Test

• Boiled potatoes or rice — bland carbohydrate options that can be portioned small
• Sandwich pieces or wraps — familiar mixed foods; test fat, fiber, and protein tolerance
• Broth or noodles — warm savory options that also contribute fluid and sodium
• Banana or soft fruit — easy to portion, but fructose and fiber tolerance vary
• Pretzels or crackers — portable carbohydrate and sodium; pair with fluid to thirst
• Commercial purées or meal drinks — check concentration, ingredients, and storage requirements in training

Hourly Fueling Plan

This is a decision framework, not a clock-based menu. Record what you actually tolerate on long training days and write a range plus fallback options for race day.

Hydration and Electrolytes

Both inadequate fluid intake in demanding conditions and excessive drinking can be dangerous. Exercise-associated hyponatremia is a low blood-sodium state most strongly associated with drinking beyond the body's ability to excrete fluid; sodium loss can contribute, but taking salt does not cancel out overdrinking.

• Use thirst as the starting signal and adapt to weather, intensity, and your practiced response rather than forcing an hourly volume.
• Include sodium through tested food or drink if useful, but do not use a universal capsule schedule or assume it prevents hyponatremia.
• Treat body mass as context, not a hydration diagnosis. Fuel use, glycogen-associated water, food in the gut, and swelling all affect weight during an ultra.
• Use the whole symptom pattern. Bloating, nausea, low urine, swelling, and thirst are not specific enough to self-diagnose a sodium disorder.

When Your Stomach Shuts Down

GI symptoms can occur at any point and range from mild food aversion to a medical problem. Heat, pace, concentrated carbohydrate, large boluses, unfamiliar ingredients, and excessive or insufficient fluid can all contribute. Do not assume every case will resolve on its own.

• Slow down or walk. Lower intensity may reduce gastrointestinal strain.
• Try a tested alternative texture. Some runners tolerate small sips; others do better with bland solids.
• Eat tiny amounts frequently rather than trying to force a full serving.
• Reduce known triggers such as high fat, fiber, dairy, or concentrated sweetness only if your training has identified them.
• Seek medical help for repeated vomiting, severe or localized abdominal pain, blood, confusion, collapse, or inability to keep fluid down.

Caffeine Strategy

Caffeine can improve endurance or alertness for some athletes, including under sleep deprivation, but benefits and adverse effects vary. Fixed clock times and doses are not appropriate for every body size, habitual intake, medication, health history, or race start time.

• Test it late in training runs, including the exact product, serving, and combination with food.
• Use the lowest practiced amount that helps and follow product and clinician guidance rather than improvising concentrated doses.
• Count every source, including coffee, cola, gels, chews, tablets, and energy drinks, to avoid accidental stacking.
• Stop or avoid it if it causes palpitations, marked anxiety, tremor, or worsening GI symptoms; discuss use beforehand if pregnant or if you have a heart condition or interacting medication.
• Do not use caffeine to mask medical warning signs or to replace sleep in events where a safe sleep break is available.

Night Nutrition

Appetite and food preferences may change overnight. Plan more than one tested option:

• Temperature can affect appeal. Test warm broth, soup, or rice as alternatives to cold food.
• Flavor fatigue can develop. Carry familiar neutral and savory options as well as sweet carbohydrate sources.
• Familiarity reduces guesswork. Use foods whose portion size, ingredients, and storage have worked in training.

Common Mistakes

• Trying new foods on race day: Test ingredients, portions, and storage conditions in training.
• Using one rigid target: Write a practiced range and fallback options instead of forcing calories through escalating nausea.
• Depending on one texture or flavor: Carry tested sweet, neutral, savory, liquid, and solid choices where practical.
• Forcing fluid or salt: Plain water is not inherently dangerous; drinking beyond losses is the principal preventable driver of exercise-associated hyponatremia, and salt does not neutralize that risk.
• Improvising caffeine: Uncounted or concentrated sources can compound side effects when judgment is already impaired.