Fuel for runners: what to eat before, during and after a race

In short Eat a varied diet day to day, load up on carbs before long races, test everything you'll swallow on race day in training, drink to thirst and recover with carbs and protein.

The engine runs on carbs

When you run, your body mainly burns two fuels: fat, of which it has almost unlimited reserves, and carbohydrates, stored in muscles and liver as glycogen. The faster you run, the bigger the share of carbs. The problem is that this store is limited: roughly an hour and a half to two hours of sustained effort is often quoted before it runs out.

That's where the famous marathon "wall" comes from, often somewhere after 30 km: legs turn to concrete, pace collapses and morale with it. Good news: nutrition exists precisely to push that wall back, or to never meet it.

Day to day: the runner's plate

No miracle diet or magic powder needed. A runner's diet looks like a balanced diet, simply adjusted to the training load.

• Starches at every meal: pasta, rice, bread, potatoes, couscous, quinoa, oats. They fill the tank. The busier the week, the bigger their share.
• Protein every day: eggs, fish, meat, dairy, pulses, tofu. It helps muscles repair after sessions.
• Fruit and vegetables, plenty and colourful: vitamins, minerals, fibre.
• Good fats, in moderation: vegetable oils, nuts, oily fish.
• Water, throughout the day.

A simple rule of thumb: if you're always hungry, feel drained in every session or lose weight without meaning to, you probably aren't eating enough for what you run. Running a lot on too little food exhausts you, injures you and ends up making you go backwards. If so, talk to a doctor or a sports dietitian.

The days before: carb loading

For a 5K or 10K, your usual diet is plenty: the effort is too short to empty the tank. For a half, and especially a marathon, the two or three days before the race are for filling up.

In practice, you increase the share of starches at each meal and cut back a little on fibre and fat, which take up room and digest slowly. For a marathon, sports nutrition guidelines often quote around 10 to 12 grams of carbohydrate per kilo of body weight per day during the 36 to 48 hours before the race. That's a lot, and it doesn't mean doubling everything: you're running little that week, the idea is to shift your plate towards carbs, not to overfill it.

A few ideas to get there without stuffing yourself: bread or cereal at breakfast, rice or pasta at lunch and dinner, carb snacks (banana, fruit purée, gingerbread, cereal bars), fruit juice. You may feel a little heavier: that's normal, glycogen is stored with water.

The night before, keep it simple: a dish you know, not too late, not too fatty, not too spicy. The pasta party is a celebration, not a competition.

Race morning

Breakfast is usually eaten two to three hours before the start, to leave time to digest. It should be high in carbs, low in fat and fibre, and above all already tested before a long run. Classic examples: white bread or crackers with honey or jam, a yoghurt, a banana, rice pudding, a hot drink.

If your start is very early or your stomach is fussy, a light snack an hour before (fruit purée, half a banana, a few biscuits) can be enough. And coffee: if you usually drink it, keep your cup. If you never do, today isn't the day to start.

During the race: feeding the engine

Over 10K, no need to eat: a few sips of water if you're thirsty. Beyond an hour of effort, carbs during the race become useful, and in a marathon they're often decisive.

The guidelines most often quoted by sports nutrition research:

• from 1 to 2.5 hours of effort, around 30 to 60 grams of carbohydrate per hour;
• beyond that, up to 90 grams per hour for runners who have trained their gut, with products combining glucose and fructose.

For reference, a standard gel usually provides 20 to 30 grams of carbs: check the label. Start early, around 40 to 45 minutes in, then take your fuel at regular intervals rather than waiting for a dip. A gel always goes down better with a little water.

Gels, sports drinks, fruit chews, bars, dried fruit: the format doesn't matter, as long as you've tested it. Which brings us to the golden rule.

Train your gut, not just your legs

The gut can be trained, like calves. A stomach that has never had a gel while running may protest on race day, and not quietly. Use your long runs as dress rehearsals: same breakfast, same gels, same fuelling rhythm as planned for the race.

Also check the runner's guide for what will be served at aid stations (sports drink, water, fruit, sugar) and test it, or plan to carry your own products. Nothing new on race day: it can't be said enough.

Drinking: not too much, not too little

Hydration is an area where you can overdo it. Drinking too much, especially plain water over a long race, can dangerously lower sodium in the blood: that's hyponatraemia, rare but serious. Not drinking enough, on the other hand, raises your heart rate and drops your performance, especially in the heat.

Sensible guidelines:

• arrive well hydrated, without forcing litres down the day before;
• during the race, drink to thirst, in small sips, at aid stations;
• in strong heat or if you sweat a lot, a sports drink containing sodium is better suited than water alone;
• gaining weight during a race is a sign you're drinking too much.

After the line: recovery starts at the table

In the hours after the finish, your body has two priorities: refill its stores and repair its muscles. The winning combo pairs carbs and protein: a sandwich, chicken and rice, a bowl of cereal with milk, a yoghurt and fruit. The finish-line food is there for the first snack, the real meal comes after.

Keep drinking, add a little salt if you've sweated a lot, and treat yourself to what you enjoy: you've earned it. Alcohol, however, slows rehydration and recovery. The victory drink can wait until you've drunk and eaten.

Supplements: be careful

For the vast majority of amateur runners, a varied diet covers their needs. Before taking a supplement (iron, vitamin D, magnesium, protein powder), talk to your doctor: too much brings nothing, and some may be inadvisable. If you race in competition, choose products guaranteed free of banned substances.

Finally, if you follow a specific diet, such as vegetarian or gluten-free, or have digestive issues when running, a sports dietitian can help you build a tailored plan.

In short

• Day to day: starches at every meal, protein every day, fruit and veg, water.
• Before a half or marathon: two or three days of carb loading, cutting back on fibre and fat.
• In the morning: a carb-rich breakfast, two to three hours before, already tested.
• During: from one hour of effort, 30 to 60 grams of carbs per hour, starting early.
• Drink to thirst, without excess, with sodium when it's hot.
• After: carbs and protein in the following hours.
• And always: nothing new on race day.

And if you're running with a Leg Up tattoo on your calf, one last tip: take your proof photo before diving into the finish-line food. Fingers sticky with fruit chews and a phone screen don't mix.

This advice gives general guidelines, not a prescription. If you have a medical condition, take medication or have any doubt, ask a doctor or dietitian.