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Marathon Fueling Guide: What to Eat, When, and How Much

September 2026 · 10 min read

Carb-Loading (2-3 Days Before)

Carb-loading increases your muscle glycogen stores from ~90 min to ~3+ hours of fuel. Target 10-12 g of carbs per kg of body weight per day for 2-3 days before race day.

• For a 70 kg runner: 700-840 g of carbs per day
• Reduce fiber and fat (they slow digestion)
• Favor white rice, pasta, bread, bananas, honey, sports drinks
• Use our fueling calculator for your exact numbers

Pre-Race Breakfast (3-4 Hours Before)

• 200-300 g of easily digestible carbs
• Oatmeal + banana + honey, or white toast + jam
• Avoid high-fat, high-fiber, or high-protein foods
• 500 ml water, stop drinking 60 min before start

During the Race

Your body can absorb ~60-90 g of carbs per hour during exercise (with gut training). Plan your intake:

• 60 g carbs/hour for half marathon and shorter
• 90 g carbs/hour for marathon (2:1 glucose:fructose mix)
• Start fueling at 30-45 minutes, then every 20-30 min
• 1 gel (~25g carbs) every 25-30 min is a simple strategy
• Drink 150-250 ml of water or sports drink at every aid station

Sodium and Electrolytes

Replace ~500 mg of sodium per hour. Options:

• Salt tabs (1-2 per hour)
• Electrolyte drinks at aid stations
• Salty foods (pretzels, salted potatoes at aid stations)

What NOT to Do

• Never try new foods on race day
• Don't skip fueling because you "feel fine" — glycogen depletion hits suddenly
• Don't over-hydrate (hyponatremia is real)