Marathon nutrition plan during race

What race-day fueling is actually solving

Your muscles and liver store roughly 400 to 600 g (14 to 21 oz) of carbohydrate as glycogen, plus a small amount of glucose circulating in blood. That supply covers about 90 to 120 minutes of hard running. After that, pace depends on how much carbohydrate your stomach can move into your bloodstream.

When glycogen runs low, pace falls, effort climbs, and the final 10 km (6.2 mi) can unravel quickly. Race-day fueling is not about replacing every calorie you burn; it is about keeping carbohydrate available at the exact moment your muscles need it.

Bottom line: The best marathon fueling plan is the one you have already rehearsed in training, not the most aggressive one on paper.

How many grams of carbohydrate per hour you need

Sports nutrition position stands put baseline intake at 30 to 60 g of carbohydrate per hour for exercise lasting one to about 2.5 hours. For longer events, 60 to 90 g/h improves performance in most trained runners when the gut will tolerate it.

Above roughly 60 g/h, absorption becomes the limiting factor. Glucose and fructose use different intestinal transporters, so a blend of both (often about 2:1 glucose to fructose) can push intake toward 90 to 120 g/h in well-practiced athletes.

Use the table below as a starting point based on your expected finish time, then adjust it in training rather than on race day.

Slower runners are on their feet longer and often need more total carbohydrate at a lower hourly rate. A 5-hour finisher taking 40 g/h consumes roughly 200 g of carbohydrate during the race, which is about 7 standard gels spread across the course.

Race-day fueling timeline

Learn the pre-race hours in more detail with this pre-race meal timing guide.

Fluids and sodium at every aid station

Marathon aid stations are usually placed every 1.2 to 1.9 mi (2-3 km), which means a drink opportunity every 8 to 15 minutes at race pace. Taking 4 to 8 oz (120 to 240 mL) with each gel helps the stomach empty and reduces the heavy, sticky feeling concentrated gels can cause.

Sweat sodium concentration varies widely between runners, from roughly 300 to 1,500 mg per liter (33 oz) of sweat. Salt crust on your skin, stinging eyes, or a recurring post-run headache are practical clues that you lose more than average. A sports drink or electrolyte tablet supplying 300 to 600 mg sodium per 16-24 oz (470-710 mL) is a reasonable match; see this sports hydration guide for a fuller breakdown.

Drinking far more fluid than you lose can dilute blood sodium, a condition called hyponatremia that is more dangerous than mild dehydration. Drink to thirst with a planned amount attached to each gel rather than forcing large volumes at every station.

Gels, chews, sports drink, or real food

All four formats work; the right choice depends on pace, stomach tolerance, and how easily you can open and carry the item. Most runners mix two formats so carbohydrate is spread across the race instead of dumped in a few large doses.

• Gels: about 22-30 g carbohydrate per packet, weighing 25-30 g (0.9-1.1 oz). Fastest option at race pace; take with water rather than a sports drink if you are sensitive.
• Chews or blocks: about 5 g carbohydrate per piece, so 3 pieces is roughly a gel-sized dose. They require chewing, which some runners find easier on the stomach.
• Sports drink: a 16-24 oz (470-710 mL) bottle can deliver 30-45 g carbohydrate plus sodium and fluid.
• Real food options: 1 banana (118 g / 4.2 oz, about 27 g carbs), 2 dates (48 g / 1.7 oz, about 30 g carbs), 1 oz raisins (28 g, about 22 g carbs), 1 oz pretzels (28 g, about 22 g carbs), 1 cup cooked white rice (158 g / 5.6 oz, about 45 g carbs), 1 medium sweet potato (150 g / 5.3 oz, about 30 g carbs), 1 tbsp honey (21 g / 0.7 oz, about 17 g carbs), and 1 cup orange slices (180 g / 6.3 oz, about 21 g carbs).
• Solid items tend to sit better at lower intensity or during walk breaks in the middle miles.

Compare carb density per portion with this banana nutrition page and our oatmeal nutrition breakdown before you build your menu.

Caffeine, gut training, and rehearsal

Caffeine improves endurance performance at roughly 3 to 6 mg per kg of body weight taken about 60 minutes before the start. For a 70 kg (154 lb) runner that is 210 to 420 mg, which is more than most people expect. A smaller late-race dose of 50 to 200 mg near mile 18-20 is a common alternative when a full pre-race dose feels too strong.

A gut that has never handled 80 g/h on the run will not handle it on race day. Build up in training: start at 30-40 g/h on long runs, add about 15 g/h every second long run, and hold your target intake for at least two runs of 2.5 to 3 hours.

Track brands, flavors, fluid volumes, and timing in one place so race day repeats a proven pattern. Our carbohydrate calculator turns body weight, pace, and a finish-time goal into grams per hour, and the Victura app logs what you actually took so the next long run can copy it.