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How to carb load before a marathon

Updated: Apr 10

It's coming into marathon season and carb loading is term often discussed around this time.

These questions will all be answered in the following blog.

If you want an easy life, I have a carb loading meal plan available. Follow this to maximise your carb stores for enhanced performance.

How to carb load for a marathon

What is carb loading?

Carb loading is the practice of eating a higher amount of carbohydrate rich foods before an endurance event. Guidelines says 12g per kilo of body weight of carbs should be eaten each day, and you should do this for 4 days. This is hard and is a lot of food to eat without planning. Any increase will be beneficial, but this is the optimised suggestions!

Does carb loading before a marathon work?

In short, yes. Your body doesn't store much carbohydrate. Normally just enough to fuel 1 hour of exercise. This can be as much as doubled by carb loading! This means you feel more energised for your event and will delay the time until you hit the wall (on a side note 'the wall' is entirely avoidable if you fuel properly before and during. See my marathon nutrition strategy).

To summarise carb loading makes you feel more energised and delays your time to fatigue.

In a research study, marathon runners which followed a nutrition plan made by a nutrition professional were 11 minutes quicker on average than runners which followed their own plan. Part of this is definitely due to proper carb loading before.

How do you carb load before a marathon?

The gold standard is to eat 12g per kilo of body weight of carbs for 4 days. However, any increase in carb intake will be beneficial. The heavier you are the harder it is to meet these numbers. Carby drinks like fruit juice, smoothies and non-alcoholic beers may be useful as they contain a lot of carbs and do not fill you up as much as a meal.

Other carb dense foods are rice, pasta, potatoes and baked goods. Don't worry about the health effects of carb loading as this is a short term practice. If you do the event, all the carbs are going to be used as energy anyway!

how to carb load before a marathon foods

To put the volume of carbs into perspective, an average sized jacket potato is about 70g of carbs.

You can see why meeting the requirements requires planning.

You will also want to practice this before the race to train your stomach and not cause stomach upsets before your race. You'll likely find it makes you feel unwell or groggy to start with.


As you can see, carb loading requires considerable planning. If you want a meal plan with the planning already done see my carb loading meal plan.


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