Nutrition
You have trained for months. Your fitness is there. Race-day nutrition is the variable that will determine whether that fitness translates into the time on the clock you deserve. Here is exactly what to do at every stage.
Two to Three Days Before
Carbohydrate loading is not a myth. The science is clear: maximising glycogen stores in the two to three days before a marathon significantly reduces the risk of hitting the wall and improves race performance. The target is 7 to 10 grams of carbohydrate per kilogram of body weight per day during this period.
For a 70kg runner, that is 490 to 700 grams of carbohydrate per day, which is substantially more than most people eat. In practice, this means making carbohydrate the focus of every meal: porridge or toast for breakfast, a large portion of rice or pasta for lunch, and pasta, potatoes, or bread for dinner. Sports drinks, fruit juice, and bananas can help hit the target without feeling uncomfortably full.
During the loading phase, reduce fat, fibre, and protein relative to your normal intake. High-fibre foods like vegetables, pulses, and wholegrain bread increase the risk of digestive discomfort during the race. Novel foods, restaurant meals, and anything you have not eaten regularly before training runs should be avoided entirely. This is not the week to try something new.
Alcohol should be avoided for at least 48 hours before the race. Even moderate drinking disrupts sleep quality and impairs glycogen storage.
"The carb loading phase is not about eating everything in sight. It is about methodically filling your glycogen stores with foods your gut already knows how to handle."
Race Morning
Race morning breakfast has one job: top up liver glycogen, which is depleted overnight during sleep, without causing digestive discomfort during the race. Eat three to four hours before the start, giving your stomach time to clear before you run.
The right breakfast is one you have eaten before long training runs and know your body tolerates. Typical options include white toast with peanut butter and banana, porridge with honey, or bagels with jam. The exact meal matters less than the fact that it is familiar, easily digestible, and carbohydrate-focused. Aim for 1 to 2 grams of carbohydrate per kilogram of body weight.
In the 60 minutes before the gun, you can take an optional 20 to 30g carbohydrate top-up, a gel or a small sports drink, in the final 15 to 20 minutes before the start. This avoids the insulin response that can cause a temporary blood sugar dip if you eat carbohydrates 30 to 60 minutes out. Many elite runners take a gel on the start line.
Stay hydrated in the morning but do not overdrink. Sipping 500ml of water or a sports drink in the two hours before the race is sufficient for most conditions. If it is warm, increase this modestly.
During the Race
This is where most recreational marathon runners under-deliver. The body cannot store enough glycogen to fuel a full marathon at race pace without external top-up. Consistent fuelling is not optional: it is the difference between a controlled race and a catastrophic last five miles.
Start taking on carbohydrates at around 30 to 40 minutes into the race, before you feel like you need them. At this point your glycogen stores are full and the gel is contributing to blood glucose maintenance rather than emergency repair. Take a gel every 20 to 25 minutes from that point, washing it down with water at the next aid station.
Most standard gels contain 20 to 25 grams of carbohydrate. At one gel every 20 to 25 minutes, you are taking on 48 to 75 grams of carbohydrate per hour, which is within the recommended range for most runners. Some well-trained athletes can absorb 60 to 90 grams per hour using dual-source carbohydrates (a mix of glucose and fructose), but this requires gut training in advance.
Caffeine has a well-evidenced performance benefit in endurance exercise. Many runners use caffeinated gels in the second half of the race, typically after mile 14 to 16, to boost mental alertness and reduce perceived effort. If you use caffeine, make sure you have used it in training first. Using it for the first time on race day introduces unnecessary risk.
Drink to thirst, not to a fixed schedule. At each water station, take a small cup if you feel you need it. Electrolyte drinks are preferable to plain water where available, as they maintain sodium balance and improve fluid absorption. Do not drink large quantities at any one stop: sipping is more effective than gulping and reduces the risk of a stitch.
The Recovery Window
What you eat after a marathon matters more than most runners realise, both for how you feel in the following days and for how quickly your body recovers. The muscles are damaged, glycogen is depleted, and the immune system is temporarily suppressed after 26.2 miles of racing. Nutrition is the primary tool for addressing all three.
In the immediate post-race window, your muscles are highly receptive to glycogen replenishment and protein synthesis. Aim for a combination of carbohydrates and protein as quickly as is practical after finishing: a recovery drink, chocolate milk, a protein bar with a banana, or whatever you can stomach in that state. The exact food matters less than the timing. Waiting until you feel hungry means missing the optimal recovery window.
Continue eating regularly and prioritise carbohydrates and protein across all meals. Appetite is often suppressed after a marathon due to the inflammatory response, but eating through this suppression accelerates recovery. Anti-inflammatory foods, oily fish, berries, turmeric, and leafy greens, can help manage the soreness of the post-race days. Alcohol should be avoided for at least 24 hours as it impairs muscle protein synthesis and sleep quality during the period when both are most needed.
Common Questions
Eat a familiar, carbohydrate-rich meal you have eaten before training runs. Pasta, rice, or potatoes with modest protein and minimal fat and fibre work well. Avoid anything new, anything very spicy, and large amounts of vegetables. Eat your main meal earlier in the evening to allow digestion before sleep.
Most runners taking one gel every 20 to 25 minutes from around 40 minutes in will consume 4 to 6 gels over a marathon. Runners targeting sub-3:30 should aim for 5 to 6. Always practise this exact strategy in training before race day.
Most runners rely on gels, chews, or sports drinks during a marathon rather than solid food, as these are absorbed more quickly during high-intensity exercise. For most marathon runners, gels are the most practical and efficient fuelling strategy.
Drink to thirst, not to a fixed schedule. Hyponatraemia (low blood sodium from overdrinking) is a genuine risk, particularly for slower runners out for four or more hours. Prioritise electrolyte drinks over plain water and take small cups at each station rather than large quantities.
In the 30 minutes after finishing, aim for a combination of carbohydrates and protein. Within the next two hours, eat a full meal containing carbohydrates, protein, and healthy fats. Recovery nutrition is critical for muscle repair and affects how you feel in the week following the race.
Summary
Marathon nutrition is a skill that sits alongside training, not separate from it. Runners who nail their fuelling will always outperform runners of the same fitness who do not. Load carbohydrates in the days before, eat a familiar breakfast on race morning, start fuelling early in the race, and take gels consistently at regular intervals. The plan is simple. Executing it under the pressure of race day requires practice, which is why every long training run of 16 miles or more should include your full race-day fuelling protocol.
At JM Coaching, race-day nutrition strategy is built into every coaching programme. Your coach will work with you on what to eat, when, and how to practise it in training. If you want to learn more, the services page explains what is included in each coaching level.
Founder of JM Coaching, 2:08:45 marathon runner and Great Britain international. Coaching runners of all abilities since 2013. Read his full profile.
Your JM coach builds your race-day fuelling plan into your training from week one.
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