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.
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.