My Account

29 September 2022

How to Carb-Load for Marathon Week


We want to ensure #TeamGSN are fully prepped on their race day protocol.



With the London Marathon coming up this Sunday, it’s a good time to talk about how what you eat affects how you run. Carb-loading is an important strategy advocated by runners and nutritionists to boost race performance.

Carb-loading involves the intake of high carbohydrates to increase the stores of muscle glycogen (energy). Starting around 2-3 days to a week prior, carb-loading will allow the maximum muscle glycogen uptake for optimum performance…



How to calculate your Bespoke Carb-Load


First of all you’ll need to determine how many carbs you need each day. The recommended amount for an effective carb load is 8-10 grams of carbohydrate per kilogram of bodyweight (each day). To calculate your daily carbohydrate needs , multiply 8 x (your bodyweight in kg). For example, a 70 kg runner would calculate 8 x 70 = 560 grams of carbohydrate per day.



 5 Days before Marathon


 Increase carbohydrate portions in your meals, opt for simple carbohydrates, some perfect examples include Oats, Potatoes, Rice, Pasta. Just remember: High Carb – low protein and fat diet.



3 Days before Marathon


Maintain high carb diet & keep adequate hydration levels.



2 Days before Marathon


From 2 days before raceday, carbs should be 85-95% of your diet. Ensure you source your intra run snacks/ hydration. Also, start to lower fiber intake if you’re concerned about GI upset.



The Night Before


Your dinner should be relatively small, but carb-heavy & make sure to eat on the early side so you have lots of time to digest. Ideally, you want to wake up hungry on race day —not full and bloated from the night before.


Race Day  


Include a race breakfast of 2g/kg carbs. We recommend overnight oats as they’re easily digestible and the perfect carb source. Add electrolytes to your water intake (5-10ml/kg every 10k). You want a minimum of 20-30g/ carbs every 10k or 60 mins which looks like 7-10 sweets/ gel. Avoid high fat snacks during run, instead opt for honey, energy gels, mars bars, dates etc. The max you can digestively get across your system and oxidise without distress is 60g/hr or 90g/hr if using glucose and fructose. You have to be preemptive with your nutrition. Waiting until you need it is a recipe for hitting an absolute plateau or not making it across the finish line – do what works for YOU.




Hydration, Hydration, Hydration…

Glucose requires water to store as glycogen. Additionally, this will help ensure that you are hydrated going into the marathon. Isotonic drinks, sweets, water and energy gels are gold-dust on race day & they will supply vital energy that is needed for your marathon.

Aim to drink 5-10ml/kg every 10K. Drink this amount 2hrs pre run to ensure you are hydrated.




We wish you all the best of luck in your race, from all the GSN Team – go smash it! 









Shop Here