Marathon Fueling: How to Fuel a Marathon

• Carb loading: in the two to three days before the race, shift a larger share of your calories to carbohydrate while easing back on training volume.
• Pre-race meal: eat 2–4 hours before the start. Keep it familiar, carb-heavy, and low in fat and fiber.
• Top-up: many runners take a small carbohydrate dose 10–30 minutes before the gun.
• Fluid: drink normally in the hours beforehand rather than forcing large volumes at the last minute.
• Nothing new: every item above should already be tested in training.

• Carbs per hour: common guidance is roughly 30–60g per hour, and trained athletes go higher when they've practiced it.
• Start early: begin fueling in the first 30–45 minutes, well before you feel empty.
• Frequency: small, regular servings every 30–45 minutes are usually easier to handle than large, occasional ones.
• Water: take fluid with each carbohydrate serving; concentrated fuel needs water to go down well.
• Electrolytes: add sodium based on heat, duration, and how heavily you sweat.
• Stay flexible: if your stomach protests, slow the rate rather than stopping fueling completely.

• Carbohydrate first: start replacing glycogen in the hours after finishing.
• Add protein: pair carbs with protein at your first real meal.
• Rehydrate steadily: fluid plus sodium over several hours beats one large drink.
• Eat what you'll actually eat: an imperfect meal you finish beats a perfect one you skip.

One GoDough serving is 20g of carbohydrate and 100 calories. Here's what a roughly 40g-per-hour plan looks like for a four-hour marathon.

Adjust the interval to your target carbs per hour: every 45 minutes is about 27g/hour, every 30 minutes is 40g/hour, and every 20 minutes is 60g/hour. Rehearse the exact plan on at least two long runs before race day.