A half-marathon is not half a marathon when it comes to food. Most runners finish in 1:25 to 2:20, at a sustained pace of around 80 to 85% of their maximal aerobic speed. At that intensity, your glycogen stores are heavily drawn on from the first hour. Eating well in the days before, on the morning and during the race is how you avoid fading in the final kilometres. Here’s the complete guide, from D-7 to recovery.

In short: you don’t need a week of carb-loading for a half. Eat normally until D-3, increase carbohydrate the day before (and two days before if you’ll run longer than 2 hours), have an easy-to-digest breakfast 3 hours before the start, and aim for 30 to 60 g of carbohydrate per hour during the race if you’ll be out for more than 1:15. Everything you use on race day should have been tested in training.

Why a half isn’t a mini-marathon

Your body stores around 400 to 500 g of glycogen in your muscles and liver, or 1,600 to 2,000 kcal. For a 10K, that’s plenty. For a marathon, it isn’t enough without fueling. The half sits in between: the intensity is higher than in a marathon, so you burn through your stores faster, but the race is short enough that a few adjustments do the job. There’s no need to copy a marathon runner’s preparation; adapt it to your finishing time.

D-7 to D-4: balanced, light eating

The week starts with no drastic changes. Your training eases off, and your eating stays balanced:

• starchy foods at every meal (pasta, rice, potatoes, bread, couscous);
• lean protein (poultry, fish, eggs, dairy, pulses);
• vegetables, preferably cooked towards the end of the week;
• at least 1.5 to 2 litres of water a day.

There’s no need to eat more “to build up stores”: with lighter training, your stores fill up naturally.

D-3 to D-1: more carbohydrate, at the right time

This is where carb-loading happens. For a half, it’s short, and how long it lasts depends on your finishing time:

Your half-marathon time	Carb-loading
Under 2 hours	the day before (D-1)
Over 2 hours	two days before and the day before (D-2 and D-1)

On those days, carbohydrate becomes the base of every meal: around 7 to 10 g per kilo of body weight per day, or roughly 500 to 700 g for a 70 kg runner. To get there without stuffing yourself:

• increase your portions of starchy foods and add easy sources (white bread, rice, fruit purée, fruit juice, honey);
• cut back on fibre (pulses, raw vegetables, wholegrains) and added fat, which slow digestion;
• keep some protein, without cutting it out;
• drink regularly: each gram of glycogen stored comes with about 3 g of water. A small weight gain (a few hundred grams) is therefore normal.

The day before: a sensible pasta party

Dinner the night before isn’t a competition. Eat early, around 7 to 8 pm for a morning race, and keep it simple: a good plate of pasta or rice, a light sauce (tomato rather than cream), a little chicken or fish, and a sweet dessert such as fruit purée or rice pudding. No alcohol, no spicy dishes, nothing new.

Race morning: breakfast

Have breakfast about 3 hours before the start. It should provide easy-to-digest carbohydrate, with little fibre and little fat. For example:

• white bread or toast with jam or honey;
• a bowl of rice pudding or fine porridge oats;
• a very ripe banana;
• a hot drink and a glass of water.

If the start is very early, have a lighter meal 2 hours before, then a small snack 30 to 45 minutes before the start (a very ripe banana, a few dates or a gel). Drink in small sips, 150 to 200 ml every 20 to 30 minutes, without gulping a large volume just before the start. If you’re used to coffee, you can have some; if you never drink it, today is not the day to start.

During the race: fueling to match your time

How much carbohydrate you need during a half depends on your finishing time:

• Under 1:15: water is usually enough, as long as your stores are full at the start. A gel or a mouth rinse with a sugary drink can help towards the end.
• 1:15 to 2:30: aim for 30 to 60 g of carbohydrate per hour, starting around 30 to 40 minutes in, then in small amounts every 15 to 20 minutes.

Sports drinks are the most complete option: they provide water, carbohydrate and sodium at the same time. Gels are handy, but take them with a few sips of water. Bars are hard to chew while running: save them for the bike. And always test your products in training, at race pace.

After the race: recovery starts on your plate

Within an hour of finishing, combine carbohydrate and protein: chocolate milk, a drinking yoghurt with a banana, or a sandwich. If you’re not hungry, start with a drink. Rehydrate with mineral-rich water or a recovery drink, then have a proper full meal in the hours that follow. In the days after, balanced eating is all you need.

Mistakes to avoid in the final week

• Doing a 6-day carb-load as if for a marathon.
• Eating high-fibre or very fatty foods on D-1 and race day.
• Trying a new gel, drink or breakfast on race day.
• Drinking a litre of water just before the start.
• Drinking alcohol the night before.

Ograal adapts all of this to you

These guidelines are general. In Ograal, when you add your half-marathon to the calendar as a race, with its duration and your start time, the app automatically switches on carb-loading for the days before, adapts your meals (less fibre, more carbohydrate), and calculates your breakfast and fueling based on your weight and pace. For details, see How our plans are calculated.

Create your free Ograal account

Key takeaways

• A short carb-load is enough: D-1, or D-2 and D-1 if you’ll run longer than 2 hours.
• Easy-to-digest breakfast about 3 hours before the start.
• Over 1:15 of racing: 30 to 60 g of carbohydrate per hour.
• Nothing new on race day.
• Carbohydrate and protein within an hour of finishing.

Sources

• Thomas, D. T., Erdman, K. A., Burke, L. M. (2016). Nutrition and Athletic Performance. Joint Position Statement. Medicine & Science in Sports & Exercise, 48(3), 543-568. DOI: 10.1249/MSS.0000000000000852
• Burke, L. M., et al. (2011). Carbohydrates for training and competition. Journal of Sports Sciences, 29(Suppl 1), S17-S27. DOI: 10.1080/02640414.2011.585473
• Jeukendrup, A. (2014). A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Medicine, 44(Suppl 1), S25-S33. DOI: 10.1007/s40279-014-0148-z