Ultramarathon Fueling Strategy: The Ratio of Solid Food vs. Liquid Nutrition in a 100km Race

Introduction

Ultramarathons (ultra-marathons, typically referring to distances over 50km) are a different nutritional universe. Marathon runners can rely primarily on energy gels and sports drinks to finish, but in a 100km race, runners need to consume 5,000–8,000 calories, and liquid fuel alone simply cannot sustain them. Solid food shifts from an “optional item” to a “mandatory item,” and gut management becomes far more important than running technique itself. This article uses the 100km race as a framework to provide a systematic strategy for allocating solid and liquid fuel.

Calculating Energy Demands for Ultramarathons

Estimated Caloric Expenditure for a 100km Race

Ultramarathon caloric intake target: 250–350 kcal per hour (the gut’s actual absorption ceiling is approximately 400 kcal/hour)

The Shifting Roles of Solid vs. Liquid Fuel

Segment-by-Segment Fueling Blueprint

Segment 1: 0–30km (Start-up Phase)

This segment’s strategy is close to a marathon, focusing on high-efficiency liquid fuel:

• Consume one energy gel every 20–25 minutes (with or without caffeine depending on personal strategy)
• Take in 200ml of sports drink at each aid station
• Solid food: half a banana (light, easy to digest)
• Caffeine gel: first one after the 20km mark

Segment 2: 30–60km (Transition Phase)

Gut fatigue begins to set in, requiring a more varied fueling approach:

• Reduce energy gel frequency to one every 30–40 minutes
• Introduce solid foods: salted crackers (for sodium), maltose (a traditional Taiwanese energy source)
• Common food strategies at Taiwanese ultramarathon aid stations:
  • Salty rice porridge (at the 50km aid station): warm, easy to digest, high in sodium
  • Rice crackers or soda crackers: not cloying, easy to carry
  • Thin slices of pork jerky: a combination of protein + sodium
• Start taking electrolyte tablets, one every 45 minutes

Segment 3: 60–80km (The Test Phase)

This segment is a high-risk zone for ultramarathon gut crises:

• Reduce the proportion of sweet foods (energy gels start to cause nausea)
• Increase savory foods: white rice + pickled mustard greens, sweet potato, white toast + peanut butter
• The Taiwanese ultramarathon aid station secret weapon: instant noodles (dry-mixed) — high in carbs, contains salt, and highly accepted by Taiwanese runners
• If feeling nauseous, temporarily switch to cola or ginger tea (ginger has anti-nausea effects)
• Consume solid food every 2–3 kilometers, in small amounts each time (50–100g)

Segment 4: 80–100km (Finish-line Sprint)

Fueling strategy for the final 20km:

• Caffeine: take a caffeine gel at both the 80km and 90km marks (final boost)
• Solid food takes priority: eat whatever is easy to digest (no need to chase the perfect combination anymore)
• Cola: at this point, cola can serve as a dual-purpose fuel providing liquid carbs + caffeine
• Sugar water (emergency backup): when you can’t eat anything else, a cup of sugar water with a pinch of salt is the last resort

Local Foods at Taiwanese Ultramarathon Aid Stations

Gut-Protecting Dietary Principles for Ultramarathons

• Avoid high fiber before the race: The low-fiber diet in the 2 days before an ultramarathon should be stricter than for a marathon
• Test all foods: Every food found at ultramarathon aid stations must be tested during training
• Small amounts, frequent intake: Do not exceed 100–150g per eating session, so the gut isn’t overloaded
• Maintain temperature: In cold-weather races, warm foods (rice porridge, soup) are more easily accepted by the gut than cold foods

Practical Advice

1. Prepare a personal fueling pack: Ultramarathon aid stations offer a wide variety of items, but the food you bring yourself is what best understands your own gut
2. Communicate with your support crew: Arrange in advance with fellow runners or family members what to provide at which kilometer, to avoid making decisions while fatigued
3. Carry backup fuel: Bring at least 20% more energy gels than planned, in case aid stations run out of stock or you fall behind your planned pace
4. Learn to “eat while walking”: The walking sections of an ultramarathon are the best opportunities to fuel up

Conclusion

Finishing a 100km ultramarathon depends half on leg strength and half on your gut management ability. From Taiwanese salty rice porridge and pork jerky to maltose, local ingredients form the strongest fueling lineup for ultramarathons. Systematically planning the solid-to-liquid fuel ratio for each segment, and repeatedly testing it in training, is the only way to ensure your body still has enough energy to face the final challenge before the finish line.

Related Reading

• Ultramarathon Fueling Strategy: Energy and Electrolyte Rhythm from 50K to 100K
• Ultramarathon Fueling Strategy: Timing Management of Solid Food, Fluids, and Electrolytes
• Complete 100K Ultramarathon Fueling Rhythm Plan: The Scientific Formula for Hourly Calories, Sodium, and Solid-Liquid Switching
• Ultramarathon Nutrition Strategy: A Comprehensive Fueling Plan from Training to Race Day