Carb-loading explained

Want to know how to carb load? Sports nutritionist, James Collins explains how, when and why maximising fuel stores can greatly benefit your race performance...

Carb-loading explained

What is meant by the term 'carb-loading'?

This is used to describe a period of high carbohydrate eating that maximises the body's glycogen stores in preparation for an endurance event. The science and practice in this area has shifted a lot in recent years. Previously a 'classic' approach involved training hard to deplete the body's glycogen, followed by a seven-day, high carbohydrate diet to replenish stores.

It is now believed that carbohydrate stores can be maximised over the two days before a race. This is achieved with high carbohydrate intakes - a rough guide equates to approximately 8-10g carbohydrate per kilogram of bodyweight - so for example, a runner weighing 60kg would aim to consume 480g-600g of carbohydrate each day.

First time marathon runners, or those who find it difficult to eat regularly, may wish to begin three days before the race. There is no need to follow the old seven day approach - it may even increase fat stores in some runners.

Kiwi fruit smoothies

How and when should I start to carb-load before a race?

Ideally start to carb-load two days before an event, possibly three days for more inexperienced runners. The overall target is approximately 10g of carbohydrate per kilogram of bodyweight. More practically, this means setting up a schedule of three carb-based meals with three snacks a day (morning, afternoon and evening).

What are some different ways to carb-load?

Increasing your carbohydrate intake doesn't necessarily mean eating huge volumes of pasta. Firstly, increase the carbohydrate content of meals by adding a bigger portion of your preferred source of carbohydrate. Adding a glass of fruit juice to one of your meals will also help to up your intake.

Snacks will play an important role in reaching your goal - try to eat a high carbohydrate 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! There is no need to eat so much you are uncomfortable - just tailor each meal and snack option towards carbohydrate. Some good recipe options could include:

Rustic oat & treacle soda bread
Kiwi fruit smoothie
Cinnamon apple & raisin porridge
Cranberry & almond clusters
Dark chocolate, banana & rye loaf
Tropical smoothie bowl

Dark chocolate, banana & rye loaf

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

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

Don't worry about weight gain of a few kilograms during carb-loading. This is to be expected and much will be water weight that is bound to carbohydrate during storage in the body.

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

This article was last updated on 25 March 2019.

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 new book The Energy Plan, which focuses on the key principles of fuelling for fitness.

All health content on 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.

Comments, questions and tips

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Bush Pig's picture
Bush Pig
29th Mar, 2018
This is *so* outdated. The term "carb loading" originated from Professor Timothy Noakes in his book The Lore of Running. He has since retracted it because it causes diabetes. Even he himself became pre-diabetic from following this advice. He now promotes a lower-carb, higher-healthy fats way of eating for sustained energy.
21st Apr, 2015
Modern endurance athletes are dumping carbs and taking on the far more effective and healthier option of a high fat, high protein diet. Good explanation here:
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