How to Properly Train for a Marathon

Food and nutrition

Published on 1 September 2018
by Isabelle Huot

Running has never been more popular. Routes are getting longer and many seasoned runners register for several marathons a year. Yes, physical training is key for good performance, but so is nutrition.


Staying sufficiently hydrated is paramount! It is important to drink 400–600 mL of fluids at least two hours before a race. For long-distance challenges like marathons, opt for a sports drink. Choose one that contains 6–8 g of carbohydrates per 100 mL, 0.5–0.7 g of sodium per litre, and 75–200 mg of potassium per litre. This way, you will be sure to stay well hydrated throughout the event. Moreover, carbohydrates provide a readily available source of energy.


It is still important to hydrate while you run (0.6–2.4 L per hour) to replenish lost water, the amount of which depends on the intensity of the running and environmental factors such as heat and humidity.


It is also wise to eat foods that will boost your performance and prevent intestinal discomfort. Three to four hours before the race, eat a meal containing slow carbohydrates (grain products such as bread, cereal, rice, couscous, and pasta). The meal should be moderate in proteins and low in fat. Overloading on glycogen (5–12 g per kilogram of weight) a few days before the race will allow you to max out your reserves, thus improving performance and reducing fatigue. These tips also apply to other long endurance events!


Finally, by consulting a nutrition expert, you can create a custom nutrition plan and use it to optimize your performance.

Isabelle Huot
Doctor in nutrition