The Short Answer
Ultra nutrition is fundamentally different from marathon fueling because duration creates more opportunities for appetite, taste, and tolerance to change. Start the plan you practiced before a large deficit develops, use small familiar portions, and adjust rather than forcing food through escalating symptoms.
What Ultrarunners Actually Eat
| Situation | Priority | Options to Test |
|---|---|---|
| Plan is working | Repeat a tolerated range without chasing a perfect number | Drink mix, gels, rice, sandwiches, bananas, potatoes |
| Taste fatigue | Change flavor or texture while keeping ingredients familiar | Pretzels, crackers, broth, noodles, neutral foods |
| Mild nausea | Reduce effort and portion size; reassess concentration and fluid | Small sips or bland bites already tested in training |
| Overnight | Maintain variety and count caffeine from every source | Warm savory choices plus tolerated carbohydrate |
The Science
Research provides planning ranges rather than a universal absorption ceiling, and two different ranges are often quoted without anyone explaining that they answer different questions.
- Practical ultra range, 30–50 g carbohydrate per hour. The ISSN position stand on single-stage ultra-marathon suggests a broad 150–400 kcal per hour, often including 30–50 g carbohydrate and 5–10 g protein. This is the range that matches what most runners actually tolerate at the low intensities and long durations of 24-hour, backyard, and multiday racing.
- Upper research range, 60–90 g carbohydrate per hour. The ACSM, Academy of Nutrition and Dietetics, and Dietitians of Canada joint position stand puts intake at roughly 60 g per hour for exercise up to about 2.5 hours and up to 90 g per hour beyond that, using multiple transportable carbohydrates such as glucose–fructose mixes. Those higher rates come from a trained gut and from products designed for them.
Both are defensible; neither is a target you should adopt untested. The higher figure assumes deliberate gut training and a carbohydrate source built for high intake rates, and it is usually quoted from higher-intensity endurance research rather than from multiday events. If you see 90 g per hour on a product label or in a race guide, read it as a ceiling for trained guts, not a default. Practice the exact foods, concentrations, and portions over a gradual training build; there is no evidence-based number of weeks that guarantees tolerance. Check our best ultra nutrition products guide for specific product recommendations.
What to Practice in Training
Practice food combinations, not just individual products. A gel may work in isolation and fail after hours of sweet drink mix. A sandwich may taste perfect at lunch and feel impossible at 3 AM. Long runs are where you learn your personal order of operations: what works early, what works when you are nauseous, and what still sounds acceptable after taste fatigue sets in.
Build a small menu with categories rather than one perfect plan: liquid carbohydrate, soft bland foods, savory foods, quick carbohydrate, and warm comfort food. That gives you options when the stomach starts negotiating.
Common Fueling Mistakes
- Waiting for a large energy deficit before starting the practiced plan
- Using only sweet products until flavor fatigue makes them unusable
- Forcing food, fluid, or sodium to hit a target despite worsening symptoms
- Trying new foods on race day because they look good at the aid station
Sources
- Tiller, N.B. et al. (2019) — International Society of Sports Nutrition Position Stand: Nutritional Considerations for Single-Stage Ultramarathon Training and Racing. Journal of the International Society of Sports Nutrition, 16, 50.
- Thomas, D.T., Erdman, K.A. & Burke, L.M. (2016) — American College of Sports Medicine Joint Position Statement: Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise, 48(3), 543–568. Source of the 60 g/h and up-to-90 g/h carbohydrate guidance for longer endurance exercise.
- Costa, R.J.S. et al. (2017) — "Systematic Review: Exercise-Induced Gastrointestinal Syndrome—Implications for Health and Intestinal Disease." Alimentary Pharmacology & Therapeutics, 46(3), 246–265.