The Short Answer
Ultra nutritionis fundamentally different from marathon fueling. You're eating meals during a race, not just consuming gels. The key principle: eat early and often when your stomach is willing, because it becomes increasingly difficult to eat as the hours pass.
What Ultrarunners Actually Eat
| Phase | Hours | Common Foods |
|---|---|---|
| Early (easy stomach) | 0–8 | Wraps, rice balls, PB&J, bananas, trail mix |
| Mid-race (moderate) | 8–16 | Boiled potatoes, ramen, quesadillas, pretzels |
| Late (difficult) | 16–24 | Broth, miso soup, watermelon, flat cola, baby food |
| Survival mode | 24+ | Whatever stays down: warm broth, cola, ice cream |
The Science
The gut can absorb approximately 60–90g of carbohydrate per hour when using dual-transport formulations (glucose + fructose). Training your gut to tolerate food during exercise — known as gut training — should begin 8–12 weeks before your race. 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 calories, soft bland foods, salty foods, quick sugar, and warm comfort food. That gives you options when the stomach starts negotiating.
Common Fueling Mistakes
- Waiting until hunger appears, which is often too late in ultras
- Using only sweet products until flavor fatigue makes them unusable
- Forgetting sodium and fluids while chasing calorie targets
- Trying new foods on race day because they look good at the aid station
Sources
- Jeukendrup, A.E. (2017) — "Training the gut for athletes." Sports Medicine, 47(S1), 101–110.
- Costa, R.J.S. et al. (2019) — "Gut-training strategies for endurance athletes." Medicine & Science in Sports & Exercise, 51(10), 2029–2039.