What to Eat Before a Long Run: What Science Says
You don't need a nutrition degree to fuel a good run. Here's what the research says, in plain English.
Start with carbs.
Think of carbohydrates as your body's petrol. Before a long run, your muscles need a full tank. A clinical trial found that runners who ate a carb-rich meal before running lasted 8% longer than those who ran on empty; that's a significant difference when you're pushing through the last few kilometers.
A simple rule: eat roughly 1g of carbs per kg of your body weight, about 1–4 hours before you head out.
Add a little protein.
Carbs give you the fuel. Protein helps protect your muscles while you run. Research shows that combining the two before exercise improves endurance performance and reduces muscle damage compared to eating carbs alone.
This is exactly why peanut butter on toast with a banana works so well before a run. It naturally gives you both, without overcomplicating things.
Timing matters more than most people think.
A study on long-distance runners found that eating too close to a run, within 30 minutes, significantly increases the chances of stomach cramps, bloating, and GI discomfort mid-run. The research also flags high-fat, high-fiber, and heavy protein foods as common culprits.
The sweet spot: eat your pre-run meal at least 90 minutes before you start, and keep it light and easy to digest.
The science-backed pre-run meal:
🍌 Whole wheat toast + 2 tbsp Nutshell peanut butter + banana slices + a drizzle of honey
Carbs for fuel. Protein and healthy fats for endurance. Real ingredients, nothing added.
Enjoy,
The Nutshell Team
Nutshell peanut butter: 2 Ingredients: Dry Roasted Peanuts & sprinkle of Sea Salt. nothing else. Shop here
Sources:
- Aandahl et al. (2021). Frontiers in Sports and Active Living. DOI: 10.3389/fspor.2021.664270
- Stecker et al. (2020). Nutrients. DOI: 10.3390/nu12051483
- Frontiers in Nutrition (2025). Protein supplementation in endurance training: systematic review & meta-analysis.
- Ge et al. (2025). GI symptoms in long-distance runners. PMC12325075