How to Fuel for a Marathon: A Complete Guide for Race Day Success

It’s that time of year when Marathon and Ultra Race season is upon us, for all you out there who are currently training for London or Edinburgh then you are probably hitting that half marathon level, so now you should be looking at your fuelling strategy.

Fuelling properly for a marathon is just as important as your training. Get it right, and you’ll have sustained energy, avoid hitting the dreaded “wall,” and recover faster. Get it wrong, and you risk energy crashes, muscle cramps, digestive distress (no one wants that on the way round), or a painfully slow recovery.

Whether you’re running your first marathon or you’re a seasoned racer, understanding what to eat the day before, the morning of, during, and after the race will set you up for success.

The Day Before the Race: Carb Loading & Hydration

1. Carb Loading—The Right Way

Carb-loading is not about stuffing yourself with endless bowls of pasta. Instead, it’s about gradually increasing carbohydrate intake in the 2-3 days leading up to the race to maximize glycogen stores in your muscles. Ideally this is what you would be doing, although the science does say that you can smash it the day before with eating up to 10g Carbs per kg of bodyweight. Now work that out and that is a lot of food, so maybe eating over a few days is going to be the better option.

• Focus on complex carbohydrates: Rice, potatoes, quinoa, oats, whole-grain pasta, and fruit.
• Reduce high-fiber foods: Too much fiber (beans, lentils, or excessive veggies) can cause digestive issues on race day. You don’t want to be running around the event with what feels like another person still living inside you.
• Increase hydration: Glycogen binds to water, so drink plenty of water and electrolytes (sodium, potassium, magnesium) to prevent dehydration.

Race Morning: Keep It Simple & Familiar

2. Pre-Race Breakfast (2-3 Hours Before Start Time)

Your pre-race meal should be carb-focused, low in fiber, and easy to digest. Aim for 2-3 grams of carbs per kg of body weight (~150-250g for most runners).

• Stick to familiar foods: Race day is NOT the time to experiment.
• Avoid too much fiber, fat, or dairy: These can slow digestion and cause discomfort.
• Hydrate well: Drink 500ml–750ml of water or an electrolyte drink upon waking.

If you’re racing later in the day: Have a small carb snack (like a banana or a sports bar) 30-60 minutes before the start.

You can also look at using caffeine to give yourself that boost of energy to really go for it, I wouldn’t look at taking down a load of coffee as potentially the only running you will do is to the loo, but I would look at 2-6g per kg of bodyweight about 60 minutes before race.

During the Marathon: Fuelling & Alternatives to Gels

3. Energy Needs During the Race

For endurance events like a marathon, your body relies on both stored glycogen and external carbs to keep going.

• Aim for 30-60g of carbs per hour
• Hydration matters—drink 400-800ml per hour, depending on conditions

Avoid waiting until you feel hungry or fatigued to fuel—by then, it’s too late! Start fuelling within the first 45 minutes and stay consistent every 30-45 minutes.

4. Alternatives to Energy Gels

Not everyone gets on with energy gels. They can cause stomach distress for some runners, especially if not consumed with enough water. Luckily, there are plenty of natural alternatives that provide similar energy benefits.

Alternative Fuel Sources:

• Bananas (Many marathons provide them at aid stations)
• Dried fruit (Dates, raisins, or figs are high in natural sugars)
• Chews or gummies (Brands like Clif Bloks or homemade versions)
• Honey packets (Easy to carry and quick energy)
• Mashed sweet potato in a resealable pouch
• Mini sandwiches with jam or peanut butter
• Rice balls (A staple in ultra-endurance running)
• Also look at caffeine bullets chews that could help keep you going throughout the race if you don’t want to be spanking a tonne of caffeine before running.

Test your fuel in training to find what works best for you. Don’t wait until race day to experiment!

Hydration Strategy: Avoiding Cramps & Dehydration

Staying hydrated is more than just drinking water—you also need electrolytes to maintain fluid balance, prevent cramps, and keep energy levels stable.

• Sip water regularly (don’t chug it all at once).
• Include electrolytes if it’s hot or humid.
• Don’t overdo plain water—drinking too much without sodium can lead to hyponatremia (dangerously low salt levels).

Electrolyte Options:

• Electrolyte Tablets added to your drinks (like High 5 Zero)
• Coconut water + a pinch of salt
• Salt tablets (for heavy sweaters)

Post-Race Recovery: Replenish, Repair, Rehydrate

5. After hours of running, your body is depleted. Proper recovery nutrition is key to repairing muscles, replenishing glycogen, and preventing extreme fatigue.

• Replenish carbs & protein: Aim for a 3:1 ratio of carbs to protein to speed up muscle recovery.
• Hydrate with electrolytes: You’ve lost a lot of sodium, potassium, and magnesium through sweat—replace them!
• Keep moving: Walking post-race helps circulation and reduces stiffness.

6. Continue Refuelling Over the Next 24-48 Hours

The hours after the race are just as important as the first post-run meal. To fully recover, continue focusing on:

• Protein intake (to rebuild muscle tissue)
• Healthy fats (for inflammation control)
• Plenty of fluids (for hydration & nutrient transport)

Final Tips for Marathon Fuelling Success

• Practice everything in training—fuels, hydration, and timing. Don’t ignore this, find something that works for you, and certainly don’t change your mind on the day just because Jeff said this thing was brilliant and you should do it too.
• Don’t skip carbs—they are your primary energy source.
• Stay ahead of hunger & thirst—fuel before you need it.
• Listen to your body—if something doesn’t feel right, adjust.

Whether you fuel with traditional gels or natural alternatives, consistency is key. Plan ahead, practice in training, and set yourself up for a fun and stress-free race day, well as stress free as possible.!

If you want help with any of this and more advice on what you should be looking at, etc., then drop me a message, and let’s book you in for a chat.