Marathon Nutrition Guide

Three days out, lift your daily carbohydrate intake to 7–10 g/kg bodyweight. For a 70 kg runner, that's 490–700 g/day — about 50–100 % more carbs than a typical Western diet. Don't add fat, fiber, or volume; replace some protein and most fat with starches, white rice, white bread, ripe fruit, and electrolyte drinks.

The myth of "tapering hard then carb-loading" doesn't hold up — modern studies (Carey 2003, Burke 2011) show that one to two days of high-carb intake is enough to saturate muscle glycogen, with no advantage to longer protocols.

Eat 1–4 g of carbs per kg bodyweight, 3–4 hours before the start. For a 70 kg runner: 70–280 g of carbs. Stick to foods you've tested in training. Common options: oatmeal with honey and banana, white-bread toast with jam, a bagel with peanut butter, or a sports breakfast drink.

30–60 minutes before the start, top up with 25–50 g of fast carbs (a gel, a small energy bar, or a sports drink). Avoid fiber, fat, and protein in the last 90 minutes — all three slow gastric emptying.

ISSN 2018 maxes recommendations at 90 g of carbs per hour for events longer than 2.5 hours, achievable only with multiple-transportable carbs (glucose + fructose blends at a roughly 2:1 ratio). For a 3-hour marathon, that means ~270 g of carbs total — about 10 standard 25-g gels.

Start fueling at kilometer 8 — early enough to be ahead of glycogen depletion, late enough to avoid GI distress. Time gels to aid stations so you can wash them down with water; do not take a concentrated gel without fluid.

For elites and runners under 2:30 marathon, the modern Maurten/Beta Fuel approach uses 120 g/h — but only if extensive gut training has been done.

Baseline target: 400–800 ml/h of fluid and 500–1000 mg/h of sodium depending on temperature. The single biggest mistake is overdrinking — hyponatremia (low blood sodium) is more dangerous than mild dehydration and afflicts mid-pack runners who drink to thirst-plus.

Practical rule: drink to thirst, not to schedule. In heat (>25 °C), front-load fluid in the first half. Take sodium with every gel.

The 30-minute post-race window is when glycogen-synthesis is fastest. Target 1.0–1.2 g of carbs/kg + 20–30 g of protein within that window. A recovery drink, chocolate milk, or a sandwich with meat plus a banana all work.

Sleep is the underrated half of recovery. Aim for one extra hour of sleep per night for the three days after a marathon.