What is carb-loading?

This is a well-known form of pre-race fuelling. When you exercise, your body uses carbs for energy and any excess is converted to glycogen, the storage form of carbohydrates. Maximising these glycogen stores through a high-carb diet, combined with adjustments to your activity levels as you lead up to a race, can be vital to maintain race performance and postpone fatigue by as much as 20 per cent. ‘Carb-loading’ is the term used to describe this strategy. The science and practice of carb-loading has changed significantly over recent years. Adopting this nutritional strategy is especially important for those involved in endurance sport and events lasting more than 90 minutes.


How many grams of carbs do I need?

This will depend on your specific circumstances and your sport, for example, the latest IAAF recommendations for elite runners suggest a high-carb diet of 10-12g carbs per kilogram bodyweight over the 36-48 hrs pre-race. So, for example, a runner weighing 60kg would aim to consume around 600-720g carbohydrates per day, which of course takes a lot of planning!

Thankfully most runners won’t need this amount of carbohydrate, but you may still benefit from increasing your intake as you lead up to your race. Other recommendations suggest dietary carbs should exceed 8g per kg of body mass or 10g per kg of lean body mass.

Porridge with green apple and blueberries

How do I ensure I am eating enough carbs?

Start by recording all the food you eat for several days using a nutrition tracking app, this will allow you to calculate your current daily carb intake. Divide the grams of carbs you eat each day by your weight then compare your current intake to your carb-loading needs. As long as the amount of carbs consumed are adequate for loading, the type of carb isn’t so important, unless you are loading for one day where the glycaemic index of the food you eat may be relevant. This is because high-GI foods have a greater glycogen storage capacity than low-GI foods when loading for a limited period, such as one day, or when rapid restoration of glycogen stores is needed.

How and when should I start pre-fuelling before a race?

Ideally start your pre-fuelling two days before an event, possibly three days for more inexperienced runners or those who find it difficult to eat regularly.

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Practically, this will mean setting up a schedule of three carb-based meals with two to three snacks a day (morning, afternoon and evening).

While increasing your carbs pre-race is important, gut comfort should be prioritised before the race. This means practicing your ‘pre-race strategy’ during training in the weeks leading up to the race – and resisting the temptation to overeat the day before and especially on the morning of the race.

What are some different ways to carb-load?

There are several carb-loading programmes, with the main difference being the duration and the amount of exercise you perform. All programmes are based on the same principle: a short-term high-carb diet while temporarily decreasing activity levels. Typically, carb-loading programmes last one, three or six days.

Increasing your carb intake doesn't necessarily mean eating huge volumes of pasta. First, increase the carb content of meals by adding a bigger portion of your preferred source of carbs. Adding a glass of fruit juice or bread roll to your meals may also help your intake.

Snacks will play an important role in reaching your goal – try to eat a high-carb snack 2-3 times a day. Often this gives you an opportunity to eat foods that you've previously had to reduce, so enjoy the race preparation!

Low-residue carbs are a better option in the 2-3 days pre-race. A low-residue (also known as low-fibre) diet, reduces the residue in the gut, and may prevent gut issues during the race. This means switching to ‘white’ versions of pasta, bread and rice and avoiding dried fruit and uncooked vegetables.

Finally, there is no need to eat more than you feel comfortable with – just tailor each meal and snack towards its carb contribution.

Chicken with rice and veg

What should my portion size of carbs be at each meal?

At each meal, aim to fill half of your plate with carbs. Protein is less of a focus at the carb-loading stage, but still important for muscle tissue repair, so fill a quarter of your plate with protein. The other quarter should be filled with mixed vegetables, with a small serving of healthy fats.

Don't be concerned if you see your weight on the scales notch up a little. This is to be expected and much of this extra weight will simply be extra fluid bound to the glycogen stored in your muscles.

What are the common mistakes when carb loading?

Carb-loading can be an effective approach when done correctly, here are some common mistakes that may limit its efficacy:

1. Carb-loading when you don’t need to – for exercise durations less than 90 minutes there may be no benefit to elevating muscle glycogen stores.

2. Including too much fat – fat is part of a balanced diet but eating too much when you are carb-loading may lead to weight gain.

3. Eating too much fibre – opting for wholegrains and complex carbs when you are carb-loading may cause stomach discomfort in some people, so swap for low-fibre options.

4. Eating the wrong amount of carbs – without recording what you eat, you may be eating too much or too little. Use a nutrition app track your intake.

5. Eating new or unusual foods – the days leading into an event are important and they are not the right time to try new foods, stick to what you know.

6. Exercising too much – don’t overlook the fact that you will need to reduce the amount of physical exercise you do, this is an important step towards optimising your glycogen stores.

Pineapple fried rice in a pan

Recipes for carb loading

Get inspired with these carb-packed recipes:

Pineapple fried rice
One-pot tomato orzo
Garlic & herb bulgur wheat
Spiced veg with lemony bulgur wheat salad
Mexican-style tomato rice
Spanish-style rice & prawn one-pot
Egg-fried rice
Super veg pasta

Are you training for an event this year? Share your tips and experiences below.

This article was last updated on 29 January 2024 by Kerry Torrens.

James Collins is recognised as a leading performance nutritionist through his work with Olympic and professional sport. Over the last decade he has worked with Arsenal FC, the England and France national football teams and Team GB. He has a private practice in Harley Street where he sees business executives, performing artists and clients from all walks of life. He is the author of The Energy Plan, which focuses on the key principles of fuelling for fitness.


All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.

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