Fuel the hours you have not reached yet
Nutrition & Hydration
What to eat, when to eat, how to reduce GI distress, and the science of fueling through days of continuous movement.
Nutrition for multiday running is not a single perfect product. It is an individualized, practiced system of food and drink that can adapt when effort, sleep loss, heat, appetite, and tolerance change.
These guides give hourly fueling targets, fluid and sodium ranges, and fallback plans for 24-hour races, backyard ultras, and longer efforts where the stomach becomes part of the race strategy.
Backyard Ultra Nutrition: What to Eat Between Loops
A per-yard backyard ultra fueling plan: about 50 g carbs per yard early, 30 g on bad yards, night caffeine and protein, and how to use time at base.
What to Focus On
24-Hour Race Fueling
Plan a tested fueling range, thirst-led fluid choices, optional caffeine, and fallback foods for the full day and night.
Backyard Ultra Nutrition
Test optional food, thirst-led fluid, and rest choices that fit the time remaining before each hourly start.
Products and Practical Setup
Build a tested mix of drink fuel, gels, familiar food, warm options, and any optional electrolyte or caffeine products.
Hydration and Sodium
Use thirst as the starting signal, avoid forced fluid, and remember that sodium intake does not make overdrinking safe.
All Guides
What to Eat During a 24-Hour Race: Hour-by-Hour Plan
A 24-hour race burns roughly 8,000–13,000 kcal. Our hour-by-hour plan: 50 g carbs per hour early, about 30 g late if needed, fluid, sodium and caffeine.
Hydration and Sodium for Ultramarathons
Plan fluid and sodium for an ultra: drink to thirst, interpret sweat-rate estimates and body-mass changes, and recognize when to seek medical help.
Gut Training for Ultrarunners: A Safe Practice Guide
An optional six-week gut-practice sequence for ultrarunners, with individualized fueling, hydration and caffeine guidance plus medical red flags.
Common Questions
How should you plan energy intake?
Our default: about 50 g of carbohydrate and 200–300 kcal an hour, the top of the ISSN ultramarathon range of 30–50 g. On a bad-stomach hour drop to about 30 g rather than nothing, and move toward 60–90 g only after gut training. Vomiting or worsening symptoms mean slow down and get help, not force food. The 24-hour and backyard guides turn this into hour-by-hour and yard-by-yard plans.
Should you rely on gels for a full day?
Gels can be part of a full-day plan, but flavor and texture tolerance vary. Test whether you benefit from alternatives such as drink mix, familiar food, savory options, warm liquids, or bland fallback foods.
When should caffeine start?
Our default: none in the first daylight hours, then from nightfall about 50 mg an hour, or 1–2 mg per kg (70–140 mg at 70 kg) every two hours, the small repeat doses the ISSN ultramarathon position stand recommends. Count every source, including cola, and test the product in training. Skip it if you are caffeine-sensitive, and never use it to push through confusion or falling asleep on your feet.