Marathon Nutrition: What to Eat Before, During, and After Your Race

Why Marathon Nutrition Matters

The marathon is one of the few athletic events where nutrition directly determines whether you finish or fail. Your muscles store approximately 90–120 minutes of glycogen at marathon pace — enough to take you to around km 30–35. After that, if you have not been fuelling, you hit the wall.

The good news: hitting the wall is not inevitable. It is the predictable result of incorrect fuelling or going out too fast. With the right carbohydrate strategy before and during the race, most runners can completely avoid it.

Training Nutrition: Daily Eating During Marathon Training

During marathon training, your daily carbohydrate needs increase significantly to support high training volumes:

• Easy/recovery days: 5–6g carbohydrate per kg body weight
• Moderate training days: 6–8g/kg
• Long run days and day before: 7–10g/kg
• Protein: 1.6–2.0g per kg body weight daily, critical for muscle repair

An 70 kg runner training 60+ km per week needs approximately 420–700g of carbohydrates on high-volume days. Most runners significantly underfuel during training, which accumulates fatigue and increases injury risk.

Carbohydrate Loading: The 3-Day Strategy

Carb loading in the 2–3 days before a marathon maximises muscle glycogen stores, providing more fuel for race day. For runners targeting sub-4 hours, research consistently shows a 2–3% performance benefit.

How to carb load: In the 2–3 days before your marathon:

• Target 8–10g of carbohydrates per kg of body weight per day
• Reduce fibre intake (no large salads or legumes)
• Reduce fat intake (your stomach needs space for carbs)
• Reduce training volume significantly (you are tapering anyway)
• Focus on pasta, rice, bread, potatoes, oats, bananas

Race Day Breakfast

Eat breakfast 2–3 hours before your race start. This tops up liver glycogen (which is depleted overnight) and ensures your blood sugar is stable at the start line.

Ideal marathon breakfast:

• 2–3 slices white toast or a bagel with jam or peanut butter
• 1–2 bananas
• Sports drink or electrolyte drink (500ml)
• Coffee if you normally drink it (caffeine improves performance — use what you train with)

Mid-Race Fuelling Strategy

This is the most important and most frequently underestimated part of marathon nutrition. The goal: deliver 30–60g of carbohydrates per hour starting at km 10–12.

The Gel Strategy

• First gel: km 10–12 (approximately 45–50 minutes in)
• Subsequent gels: every 30–40 minutes
• Total gels for a 4-hour marathon: 5–6 gels (25g carbs each)
• Always take gels with water, not sports drink (to avoid too much sugar at once)

Race Day Hydration

Drink to thirst, not on a fixed schedule. Most marathon runners need 400–800ml per hour depending on conditions:

• In cool conditions (under 15°C): 400–500ml/hour
• In warm conditions (15–25°C): 500–700ml/hour
• In hot conditions (above 25°C): 700–800ml/hour

Take electrolytes (sodium, potassium) alongside water, especially in hot weather. Electrolyte tabs or gels with sodium prevent hyponatremia and help you retain the water you drink.

Post-Race Recovery Nutrition

Recovery nutrition in the 30–60 minutes after finishing a marathon significantly accelerates muscle repair and glycogen restoration:

• Carbohydrates: 1.0–1.2g per kg body weight immediately after (a banana + sports drink works)
• Protein: 20–25g within 30 minutes (chocolate milk, a recovery shake, or Greek yogurt)
• Hydration: Replace 150% of fluid lost — if you lost 1kg of weight, drink 1.5L of fluid with electrolytes
• First full meal: 2–3 hours after finishing, high carb and protein, normal fat and fibre

Foods to Avoid Before a Marathon

• High-fibre foods (beans, lentils, bran) — risk of GI distress
• Spicy or fatty foods in the 48 hours before
• Alcohol (dehydrating and impairs glycogen storage)
• New foods you have not eaten before in training
• Large portions of cruciferous vegetables (broccoli, cauliflower, cabbage)