Nutrition for Marathon Runners

Nutrition for Marathon Runners

More and more people are deciding to prepare for and run a marathon. But it’s not something trivial, and shouldn’t be taken lightly. You need to plan and know how to act. Let’s take a look from a nutritional point of view

Running a Marathon

More and more people are deciding to prepare for and run a marathon. The goal may be simply to finish it, to improve on previous marks, or get the best performance in the competition.Running marathon

And for this, besides training and taking care of oneself as much as possible, nutrition and several nutrition-related aspects are hugely important for the runner to take into account.

Daily Energy Distribution

It is very important to distribute the daily energy (kcal) from food in 4-5 intakes per day, such as:

  • Breakfast: 20-25%
  • Lunch: 10%
  • Food: 25-35%
  • Snack: 10%
  • Dinner: 15-20%

Essential Food for Runners and Marathoners


Glucose (carbohydrates) is the main substrate used by the marathon runner, along with fats. Carbohydrates are stored in the liver and muscles and are later converted into glucose. And unlike fat, carbohydrates can be exhausted during long-duration training.

Carbohydrates at breakfast are obligatorily. In the form of cereals or bread, for example. A minimum amount of carbohydrates should be eaten at dinner, although this recommendation may vary depending on whether the runner is training first thing in the morning.

Carbohydrate sources

As there is a direct relationship between carbohydrate exhaustion and muscle fatigue, it’s recommended that marathon runners consume carbohydrates on a daily basis.

Fruit and vegetables

They bring a lot of vitamins and minerals to the runner, so it’s recommended to eat these types of foods daily. 2-3 pieces of fruit a day (one of them at breakfast) is recommended. As for the intake of vegetables, at least 300 grams per day is recommended.

Fruits vegetables

Lunch and dinner are the ideal moments to consume vegetables in the long-distance runner’s diet.

Top 10 Best Carbohydrate Sources for Athletes

Importance of Carbohydrates

Daily Training

On training days, it’s sufficient just to eat properly, and no extra input is necessary except on days when long runs of more than 25km are required, when it would be advisable to consider training as a “simulation” of the day of the competition.

Depletion of glycogen deposits

Graphic 1

Modified from MC Ardle and col. 1991.

This is a graph representing the relationship between the initial content of glycogen in the muscle stores and the time until exhaustion during endurance exercise. It’s clear that without full carbohydrate (glycogen) stores before starting a marathon, the race is unlikely to be a success.

No matter how much previous training has been done and how much work we have accumulated, it will simply not be possible to maintain the race pace during the competition, as before the end the glycogen stores will have been exhausted and our race speed will have dropped significantly.

Avoiding Glycogen Exhaustion During the Race

We can avoid this fatigue from emptying the reserves during the race with 3 keys:

  • Adapting our muscles to metabolise (expend) fats together with carbohydrates during the race, in order to save the consumption of hydrates. This can be achieved with high volumes of work and moderate intensity.
  • Ingesting carbohydrates during the race.
  • Performing a glycogen overload (carbohydrates) in the days before the competition in order to start the race with a full tank.


Do you know why 'the wall' happen in exercise?

Carbohydrate Load

For a marathon or half-marathon, we need to have the deposits in the liver and muscles full.

How much carbohydrate should you consume?

Consume 10 to 12 grams of carbohydrates/kg body weight/day in the 48-72h before the start of the race.

Type of carbohydrate

The most recommended types of carbohydrates are complex ones such as pasta, rice, potatoes, bread, etc. For convenience, and to avoid copious meals (some people can’t tolerate a high volume of food intake), you can make use of carbohydrates.

Glycogen storage

These carbohydrates are stored in the muscles and the liver in the form of glycogen, and this way we’ll have our reserves full and delay the time until fatigue. But not because eating more carbohydrates is better: we need to consume the necessary amount, as if we exceed the limit of our deposits, those carbohydrates will become fat.

IF you want to find out more about this nutritional strategy, click on this Carb Loading Before Marathons

What Should You Eat After Training?


It’s best to ingest the carbohydrates as soon as possible after training to recover the spent deposits. We recommend 1.2g/kg/h during the first 4 hours after training.

It’s best to ingest them in liquid form during the first 90 minutes after finishing the training, and in the following 2 and a half hours via solid food.


On the other hand, it’s also recommended to add proteins together with carbohydrates, as it’s been shown to be more effective in filling carbohydrate reserves. It’s best to ingest about 8 grams of essential amino acids and 25% of protein carbohydrates.

For after the competitions, w”e’ll do the same post-training as in the training.

Nutrition on Race Day

Glycogen replacement

The carbohydrates we have consumed during sleep must be replenished, especially at the hepatic level (liver). So we need to have a proper breakfast.

Avoid experiments

What we have to keep in mind for the day of the competition is not to try new things (we can do that in training), so the pre-competition breakfast must have been done before during training days.

What to have for breakfast on Race Day?

Breakfast will be made some 3 hours before the competition, should contain between 200 and 300 grams of carbohydrates and consist of regular carbohydrate-rich foods such as toast, cereals, bananas, energy bars, and even pasta or rice if we feel like it, which are low in fat, protein and fibre.


And we shouldn’t forget about hydration. For this we should drink about 500ml of water with breakfast.

A very popular food to have is “porridge”, as it allows you to eat a high amount of carbohydrates in a simple way, and it’s easy to make with simple recipes like this

What to Eat Before the Race?

It is recommended that around 30-45 minutes before the competition, some additional 60-70 grams of carbohydrates (glucose, sucrose or glucose polymers) diluted in 500ml of water should be ingested, to which we can also add around 6 grams of essential amino acids.


Sports drinks or supplements are ideal for this last intake before competition.

What to Eat During the Race?

It is essential that we consume carbohydrates during the race to ensure our glycogen stores are not emptied.


Consuming around 30-60 grams per hour in takes every 20-30 minutes is recommended.

Studies have shown that the efficacy of taking these carbohydrates in solid or liquid form are similar, so we should take them as they suit us best and if we have tried them before in training, making sure they don’t cause us digestive problems. In training sessions with long runs of more than 25km, we’ll do the same as in a competition.


  1. J. L. Chicharro, D. Sánchez. (2014). Fisiología y Fitness para corredores populares. Editorial Prowellness.

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About Paloma Sala
Paloma Sala
Paloma Sala is an athlete who is constantly learning to give her best. Paloma is an experienced high performance athlete who has been doing Athletics for more than 20 years.
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