Running & Endurance
What to Eat Before Marathon Day
Most marathons fall apart in the final 10K, when the fuel runs out. What you eat in the 48 hours before the gun decides whether you start with a full tank. Here is how to load properly and what to eat on the morning.
Why the last two days matter more than the pasta dinner
Your muscles and liver can only store so much glycogen, and a marathon is long enough to drain the tank if you start it half full. That is why the last two days of eating matter as much as any long run in your block.
Real loading is spread across two days — the night-before pasta mountain mostly just leaves you bloated.
The common mistake is treating carb loading as one enormous pasta dinner the night before. That mostly leaves you bloated and sleeping badly. Real loading is spread across the 24 to 48 hours before the race, and race morning is a separate, smaller task. Get both right and you arrive topped off rather than hoping.
Carb loading: how much, and what to actually eat
To fill your glycogen stores, aim for somewhere between 7 and 12 grams of carbohydrate per kilogram of body weight per day in the day or two before the race. For most runners, targeting around 8 to 10 grams per kilogram hits the mark without turning eating into a chore.
Put real numbers on it. A 65-kilogram runner needs roughly 520 to 650 grams of carbohydrate a day; a 75-kilogram runner needs closer to 600 to 750. Those totals are genuinely hard to eat as plain rice and pasta, because the sheer volume fills you up before you reach the target. This is the one time in training when refined, low-fibre carbohydrate is your friend: white rice, white bread, plain bagels, ripe bananas, jam, honey, fruit juice, sports drinks and a bit of candy all count. Keep fat and fibre lower than usual, since both slow digestion and add bulk you do not want sitting in your gut on race morning.
A frequent error is holding your normal calorie intake steady and simply swapping in carbohydrate, which leaves you under-fuelled. During loading you are usually eating a little more overall, with most of the increase coming from carbohydrate while your training tapers down. And whatever you do, do not experiment the day before: eat foods you have eaten many times, because a novel high-fibre meal or an unfamiliar restaurant is how race weekends get ruined.
Race morning: the smaller job people get wrong
Overnight your liver glycogen drains even while you sleep, so race breakfast tops up that store and steadies your blood sugar for the start. This meal is smaller than most people think, and its size depends entirely on how long before the gun you eat it.
The guideline is 1 to 4 grams of carbohydrate per kilogram, eaten one to four hours before the start, and the rule is simple: the closer to the start you eat, the less you eat. Four hours out, a 70-kilogram runner can handle a large breakfast of around 210 to 280 grams of carbohydrate, such as a big bowl of oats, a banana, toast with honey and some juice. Two to three hours out, halve that to a bagel with jam, a banana and a sports drink. Inside two hours, keep it light: a banana and a gel, or a slice of toast.
Most experienced marathoners settle on eating about two and a half to three hours before the start. That gives the stomach time to empty so you are not running on a full gut, while keeping the fuel available. Stick to the same principles as loading, low fibre, low fat and familiar: a plain bagel with honey beats a bran muffin every time. Coffee is fine if it is already part of your normal routine.
Hydration before the start
Turning up well hydrated matters as much as being well fuelled, and you do not achieve it by drinking a litre of water at the start. In the day before, drink to a pale-yellow urine colour and add a little sodium to your fluids so you actually retain them. On race morning, sip 400 to 600 millilitres in the two hours before the start, then stop early enough that you are not queuing for a toilet at the first kilometre.
Handing off to in-race fuelling
Your pre-race plan only works if it hands off cleanly to fuelling during the race. From about 45 minutes in, aim for 30 to 60 grams of carbohydrate per hour, rising toward 90 grams if you have trained your gut for it with mixed glucose and fructose sources. Take it in small, regular doses rather than one large hit. Build the plan around your expected finish time and goal pace, practise the whole thing on a long run at least once, and change nothing on the day itself.