What is meant by the term 'pre-race fuelling' or 'carb-loading'?

Maximising the body’s glycogen stores through a high carbohydrate diet leading into the race can be vital to maintain race performance.


‘Carb-loading’ is the term used to describe this. The science and practice in this area has shifted a lot in recent years.

For elite runners, the latest IAAF recommendations highlight that this is achieved by high carbohydrate diet of 10-12g carbohydrate per kilogram bodyweight over the 36-48 hrs pre-race – so for example, a runner weighing 60kg would aim to consume of ~600-720g carbohydrate per day, which takes a lot of planning! Thankfully most runners won’t require this amount of carbohydrate, but can still benefit from increasing their intake leading into the race.

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How and when should I start my 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.

Practically this will mean setting up a schedule of 3 carb-based meals with 2-3 snacks a day (morning, afternoon and evening).

Whilst increasing carbohydrate intake 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 in – and resisting the temptation to overeat the day before or the morning of the race.

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 or bread roll to your meals can 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!

Low-residue sources of carbohydrate may also be preferred 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 alongside a small reduction weight. This means switching to ‘white’ versions of pasta, bread, avoiding dried fruit and uncooked vegetables.

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Finally, there is no need to eat so much you are uncomfortable – just tailor each meal and snack option towards carbohydrate.

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, with a small serving of healthy fats.

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 20 February 2020 by James Collins.

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.


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