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

The Science of Marathon Fuelling

Your body stores roughly 2,000 calories of glycogen in your muscles and liver — enough to power about 90 minutes of hard running. A marathon takes most runners somewhere between 3 and 5.5 hours. The arithmetic is brutal: without a fuelling strategy, you will hit the wall.

“The wall” isn’t a metaphor. It’s the point where your glycogen stores are depleted and your body switches to burning fat, which produces energy far more slowly. Your pace drops by 1–2 minutes per kilometre, your legs feel like concrete, and your brain starts negotiating reasons to stop. Proper nutrition doesn’t just improve your time — it’s the difference between finishing strong and limping to the line.

This guide covers everything: what to eat in the weeks before the race, how to carb-load correctly, what to consume during the 42.195 kilometres, and how to recover nutritionally afterwards. We’ll also look at how race conditions — heat, humidity, altitude — should change your approach.

Training Nutrition: Building the Foundation

Marathon nutrition doesn’t start on race week. The months of training that precede the event are where you build your metabolic engine.

Daily Macro Targets for Marathon Training

During heavy training blocks (peak mileage weeks), aim for:

Carbohydrates: 5–7g per kg of body weight per day
Protein: 1.4–1.8g per kg per day (supports muscle repair)
Fat: 1.0–1.5g per kg per day (essential for hormone function and joint health)

For a 70 kg runner, that’s roughly 350–490g carbs, 100–125g protein, and 70–105g fat daily.

What to Eat Around Runs

Before a run (1–2 hours): Simple carbs — toast with honey, a banana, porridge with berries
After a run (within 30–60 minutes): Carbs + protein in a 3:1 ratio — chocolate milk, a rice bowl with chicken, or a recovery shake
On rest days: Slightly reduce carbs but maintain protein to support recovery

Practice Your Race Nutrition in Training

This might be the single most important nutrition rule: never try anything new on race day. Your long runs are dress rehearsals for race-day fuelling. Use them to test:

Which gel brands your stomach tolerates (some runners react badly to certain sweeteners)
How often you need to fuel (every 30 minutes? Every 45?)
Whether you prefer gels, chews, or sports drinks
How much water you need at different temperatures

By the time race day arrives, your fuelling plan should be as rehearsed as your running.

Carb-Loading: The 72-Hour Pre-Race Window

Carb-loading is the most misunderstood aspect of marathon nutrition. It’s not about eating enormous portions of pasta. It’s about shifting your macronutrient ratios to maximise glycogen storage.

How to Carb-Load Correctly

Starting 3 days before the race, increase your carbohydrate intake to 8–10g per kg of body weight. For a 70 kg runner, that’s 560–700g of carbs per day.

Crucially, you’re not eating more total calories — you’re eating a higher proportion of carbs while reducing fat and protein. Think of it as a ratio shift, not a volume increase.

Best Carb-Loading Foods

Food	Carbs per Serving	Notes
White rice (1 cup cooked)	45g	Easy to digest, versatile
Pasta (1 cup cooked)	43g	Classic choice, pair with simple sauces
White bread (2 slices)	28g	Toast with jam is a carb-loading staple
Banana (1 medium)	27g	Portable, includes potassium
Bagel (1 large)	55g	Dense carb source
Pancakes (2 medium)	40g	Works for breakfast carb-loading
Sports drink (500ml)	30–35g	Liquid carbs are easy on the stomach
Dried fruit (50g)	35g	Concentrated energy source

Foods to Avoid Before Race Day

High-fibre vegetables (broccoli, beans, lentils) — gas and stomach distress
Spicy food — gastrointestinal risk you don’t need
Heavy dairy — can cause bloating in sensitive runners
Alcohol — dehydrating and disrupts sleep quality
Anything you haven’t eaten before — your gut is conservative; don’t surprise it

The Night-Before Dinner

Eat your pre-race dinner by 6–7 pm. Keep it simple and familiar: pasta with a light tomato sauce, white rice with grilled chicken, or a simple risotto. Avoid heavy creamy sauces, large portions of meat, or elaborate restaurant dishes. You want a satisfied stomach, not a full one.

Race Morning: The Pre-Race Meal

Eat your final pre-race meal 2.5–3 hours before the start. This gives your body time to digest while topping off glycogen stores.

What to Eat

Aim for 300–500 calories, almost entirely carbohydrates:

Toast with jam or honey (2–3 slices)
A banana
300–500ml of water or sports drink
Optional: a small bowl of porridge or a bagel

What to Avoid

Protein-heavy foods (eggs, meat) — slow to digest
High-fat foods (avocado, nuts, cheese)
Coffee in excessive amounts (one cup is fine if you’re used to it; more can cause stomach issues)
Large volumes of fluid right before the start (sip, don’t gulp)

The Final 30 Minutes

In the 15–30 minutes before the gun, you can take one final gel with a few sips of water. Some runners skip this and wait until 45 minutes into the race. Either approach works — use whatever you’ve practised in training.

During the Race: Your Fuelling Plan

This is where races are won or lost, especially for marathoners in the 3:30–5:30 finish range. Your body is burning through glycogen at roughly 1 calorie per kilogram per kilometre. Without mid-race fuelling, you’ll deplete your stores by 28–32 km and hit the wall.

The Fuelling Schedule

Timing	Action	Approximate Distance
45–60 min	First gel + water	~8–10 km
75–90 min	Second gel or sports drink	~14–16 km
105–120 min	Third gel + water	~20–22 km
135–150 min	Fourth gel or sports drink	~26–28 km
165–180 min	Fifth gel + water (if still on course)	~32–34 km

Gels vs. Chews vs. Sports Drinks

Gels — Concentrated carbohydrate packets (20–25g carbs each). Quick to consume but need water to digest. Most popular option.
Energy chews — Gummy-style carb delivery. Easier on some stomachs but take longer to eat. Good if you dislike the texture of gels.
Sports drinks — Available at most aid stations. Provide carbs, electrolytes, and hydration in one. The downside: you can’t control concentration or brand at aid stations.

Many experienced runners use a combination — carry their preferred gels and supplement with on-course sports drinks.

Aid Station Strategy

Walk through aid stations rather than trying to drink at speed. The 10–15 seconds you “lose” at each station is repaid many times over by actually getting the fluid and fuel into your body instead of down your shirt.

Grab the cup, pinch the rim to form a spout, and sip while walking. Resume running after you’ve finished drinking.

Hydration: The Goldilocks Problem

Hydration is a balance. Too little and your blood thickens, your heart rate rises, and your pace suffers. Too much and you risk hyponatremia — a dangerous dilution of blood sodium that hospitalises runners every year.

How Much to Drink

The modern consensus is simple: drink to thirst. Your body’s thirst mechanism is remarkably well-calibrated. Ignore outdated advice about drinking on a fixed schedule or “staying ahead of thirst.”

As a rough guide, most runners need 400–800ml per hour depending on conditions. In cool races like London Marathon in April or Tokyo Marathon in March, you’ll be at the lower end. In hot-weather events like Dubai Marathon in January — where despite being winter, temperatures can reach 20–25°C — you’ll need significantly more.

Electrolytes

When you sweat, you lose sodium, potassium, and other electrolytes. For races over 3 hours, electrolyte replacement matters. Options include:

Salt tabs taken every 45–60 minutes
Electrolyte sports drinks at aid stations
Electrolyte-enhanced gels

If you’re a heavy sweater (visible salt stains on your clothes after runs), consider adding an electrolyte drink the morning before the race and carrying salt tabs during.

Race-Specific Hydration Considerations

Different races present different hydration challenges:

Hot races (Dubai Marathon, tropical events) — Increase fluid intake by 20–30%. Start hydrating the day before. Consider a pre-race electrolyte drink.
Humid races — Humidity impairs your body’s cooling through evaporation. You’ll sweat more but cool less. Slow your pace and increase fluid intake.
Cold races — You still sweat in the cold, but you may not feel thirsty. Set reminders to drink at every other aid station.
Altitude races — Higher altitude increases respiration rate and fluid loss. Begin extra hydration 2–3 days before the race.

Post-Race Recovery Nutrition

What you eat in the 24 hours after the marathon dramatically affects your recovery speed. Your muscles are damaged, your glycogen is depleted, and your immune system is temporarily suppressed.

The First 30 Minutes (The Golden Window)

Your muscles are most receptive to glycogen restorage immediately after exercise. Within 30 minutes of finishing:

Consume 1.0–1.2g of carbs per kg of body weight
Add 20–25g of protein
Rehydrate with 500–750ml of fluid

Practical options: a recovery shake, chocolate milk, a banana with a protein bar, or whatever the race finish area provides. Don’t overthink it — getting something in quickly matters more than perfection.

The First 24 Hours

Eat a proper meal within 2 hours of finishing: rice or pasta with protein, vegetables, and plenty of fluids
Continue eating carb-rich meals through the day
Drink water and electrolytes — aim for pale yellow urine
Avoid alcohol for at least 12 hours (it impairs glycogen restorage and muscle repair)
Allow yourself comfort food — you’ve earned it, and the psychological satisfaction aids recovery

The First Week

Maintain higher-than-normal carbohydrate intake for 2–3 days
Keep protein intake elevated to support muscle repair
Eat anti-inflammatory foods: berries, fatty fish, turmeric, green leafy vegetables
Don’t restrict calories — your body is repairing itself and needs fuel

Special Considerations

Running on a Sensitive Stomach

Gastrointestinal distress affects up to 30–50% of marathon runners. If you’re prone to stomach issues:

Avoid high-fibre and high-fat foods for 24 hours before the race
Use isotonic gels that don’t require water
Test multiple gel brands — some use fructose, some glucose, some maltodextrin, and your gut will prefer one
Consider real-food alternatives: dates, rice cakes, or gummy bears
Practise race nutrition extensively in training

Vegetarian and Vegan Runners

Plant-based runners can absolutely fuel a marathon effectively. Key adjustments:

Protein sources: Tofu, tempeh, lentils, chickpeas, quinoa, seitan
Iron: Pair iron-rich foods with vitamin C for absorption. Consider supplementation.
B12: Supplement if fully plant-based
Carb-loading: Rice, pasta, bread, potatoes — all naturally vegan

Running in the Heat

Hot-weather marathons like Dubai Marathon demand a modified nutrition strategy:

Begin sodium-loading 2 days before the race (add salt to meals, drink electrolyte beverages)
Take electrolyte tabs more frequently during the race (every 30–40 minutes)
Use ice at aid stations — in your hat, down your neck, or in your hands
Consider carrying a handheld bottle for between-station hydration
Accept a slower pace and adjust your fuelling timing to distance rather than time markers

Building Your Personal Fuelling Plan

Every runner is different. What works for your training partner may wreck your stomach. The only way to build a reliable fuelling plan is through systematic testing during training.

Step-by-Step Plan Builder

Weeks 1–4: Try 2–3 different gel brands on easy runs. Note any stomach issues.
Weeks 5–8: Test your preferred gel during long runs. Start with one gel at 45 min, then add more as distances increase.
Weeks 9–12: Run your full race-day fuelling schedule during your longest training runs (28–35 km).
Weeks 13–16: Lock in your plan. No more experiments. Rehearse the exact products, timing, and quantities you’ll use on race day.
Race week: Buy fresh supplies of your chosen gels. Check what drinks will be on the race course — and if they’re different from what you’ve trained with, carry your own.

Record and Refine

Keep a simple log during training:

What you ate before the run
What you consumed during
How your stomach felt
Energy levels throughout
Any issues (cramps, nausea, bloating)

This data is worth more than any generic nutrition guide. Your body will tell you what works if you listen and record.

Key Takeaways

Start fuelling in training, not on race day. Your long runs are nutrition rehearsals.
Carb-load by shifting ratios, not by eating more total food.
Eat your pre-race meal 2.5–3 hours before the start — simple carbs, nothing new.
First gel at 45–60 minutes, then every 30–45 minutes throughout.
Drink to thirst. Don’t over-hydrate. Don’t under-hydrate.
Adjust for conditions. Hot races need more fluid and electrolytes. The Boston Marathon in April is very different from the Dubai Marathon in January.
Recovery nutrition matters. The first 30 minutes after finishing are critical for glycogen restorage.
Test everything in training. The most dangerous words on race morning are “I’ve never tried this before, but…”

For more on choosing the right first-time race, read our Complete Beginner’s Guide. If you’re looking for fast, flat courses to set a PR, check out The Flattest Marathons in the World.