How to Fuel a Marathon (Without Guessing)
Most marathon fuelling advice is written for someone who isn't you.
It's written for the elite athlete running a 2:30, the influencer selling a gel subscription, or the "one size fits all" plan that ignores the fact that you've got a job, a training block that hasn't gone perfectly, and a stomach that doesn't always cooperate. That's not a knock on the advice — it's just not built for real people running real marathons.
So here's the version that actually is. Science first, no dogma, nothing you need a nutrition degree to understand.
Why Fuelling Even Matters
Your body stores roughly 90 minutes to 2 hours of usable glycogen (carb fuel) before it starts running low, depending on your training and how well-fuelled you go in. Marathons take most people well past that window. When you run out, you don't just slow down — you hit the wall. Legs go heavy, pace falls apart, and everything that felt manageable at mile 16 feels impossible at mile 22.
The fix isn't complicated: you top up carbs during the race before you run low, not after. Fuelling a marathon is really just glycogen management with a bit of hydration and electrolyte strategy layered on top.
The Week Before
This is where most of your race-day fuel actually gets stored, not the morning of.
3–2 days out: shift toward more carbs, slightly less fibre and fat, so your gut isn't working overtime the night before.
Don't "carb load" by doubling your food volume. You're not trying to eat more — you're trying to fill glycogen stores, which means swapping some fat/fibre for more easily digested carbs (rice, pasta, toast, potatoes).
Keep hydration steady all week, not just the day before. A dehydrated start undoes a well-fuelled one.
Race Morning
Eat something 2–3 hours before the gun — a meal you've already practiced in training, not something new because it's race day. Aim for 1–4g of carbs per kg of bodyweight (this range is wide on purpose; some people tolerate more pre-race food than others, and that's fine). Toast with jam, a bagel, porridge with honey — simple, low-fibre, low-fat carbs that won't sit heavy.
If you're someone who gets pre-race nerves and struggles to eat, a liquid option (a sports drink or a smoothie) often sits easier than solid food.
During the Race
This is the part people either overcomplicate or ignore completely.
Target roughly 30–60g of carbs per hour, starting from around 45 minutes in — not when you first feel tired, by then you're already behind. Higher training volumes and gut-trained athletes can often push toward 60–90g/hour, but that's something to build up to in training, never to try for the first time on race day.
Sources that work for most people: gels, chews, sports drink, or a mix of all three so you're not relying on one texture for four hours. Sip fluids regularly rather than gulping — little and often beats a lot at once, both for hydration and for keeping your stomach settled.
Practice Everything Beforehand
This is the one rule that matters more than any specific number: nothing new on race day. Not a new gel brand, not a new breakfast, not a new hydration system. Your long runs are the testing ground — that's where you find out what your gut can actually handle at marathon pace, not in the week before the race when it's too late to change anything.
The Simple Version
If you take nothing else from this: eat a practiced, carb-focused breakfast 2–3 hours out, start taking in 30–60g of carbs per hour from about 45 minutes into the race, sip fluids consistently rather than waiting until you're thirsty, and never test anything new on race day. That's fuelling a marathon well — not a rigid plan to follow perfectly, just a framework to build around what actually works for your body.
If you want that framework built specifically around your training, your gut, and your race, that's exactly what 1:1 coaching is for — book a free discovery call and we'll figure it out together.
