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“If you plan to finish a marathon between 3 and 4 hours from minute 0 to 90 just drinking water is enough, if anything mouthwashes with an isotonic at the end of the stretch.”


Friday, January 26th, 2024

The sports nutrition experts of Betternakedclub clarify all the doubts about nutrition and hydration according to each level of popular marathon runner

“If you plan to finish a marathon between 3 and 4 hours from minute 0 to 90 just drinking water is enough, if anything mouthwashes with an isotonic at the end of the stretch.”

Having clear hydration and nutrition guidelines before, during and after a marathon are key to performance. with these recommendations you can learn how to do them correctly.

It is not the same to run a marathon in three, four or five hours. The nutrition and hydration needs before, during and after the race are completely different. The sports nutrition experts at Betternakedclub explain to you how to organize these two key aspects of performance:


3 days before

We are talking about a race that will last between two hours, for the fastest runners, and 5 hours, for the less experienced, we will establish that the level of intensity at which you are going to run is medium/low. The macronutrients that will provide you with energy during the race will be both fat and carbohydrate.

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Scientific evidence tells us that a carbohydrate load during the three days prior to the competition, together with a progressive reduction of the training load is enough to increase our energy reserves in the form of glycogen in the muscle.

First of all, we should clarify that glycogen is our body’s way of storing carbohydrate, mainly in the muscle and liver. This carbohydrate will later, during physical exercise, be used as a source of energy. Our carbohydrate reserves are depleted after an hour and a half of exercise, so if our goal is to perform at our best, we should take this factor into account. There is a one-week glycogen overload protocol, but it is already known that the difference is minimal compared to the 3-day protocol.

It is also important to be clear that as the intensity of exercise increases, the body uses more of this glycogen as an energy source and less fat. We give special importance to this pretext in the dinner before the competition, where we should put special emphasis on providing sufficient carbohydrate.

With which foods do I increase my daily carbohydrate intake?

– Oat flakes and corn flakes without sugar.

– Pasta, rice and whole wheat bread.

– Potato or sweet potato.

– Cous-cous or quinoa.

– Whole fruit (not juice).

Normally we speak of a window of between two and four hours between the last intake and the beginning of the test. There are people in whose case it is necessary to space them even longer, it all depends on how used you are to eat before training and how long you wait. It is here when you have to program what is going to be your last intake depending on what time the test starts.

It is a very common mistake to try to overeat before the test or not to anticipate enough, which will cause gastrointestinal discomfort and even vomiting and nausea.

We must avoid the consumption of two nutrients: fiber and fat. These will slow down gastric emptying, resulting in slower digestion. Another common mistake before a test is to change our eating habits because of it. We will always keep in mind that the time to experiment will be during the season in which we do long-distance training. That is when we will try new foods and progressively increase the amount of pre-workout food, so that on the day of the test we will know for sure which foods are good for us before exercise.

The recommended amounts of carbohydrate (3 hours before exercise) are 2 grams of carbohydrate per kilogram of body mass. If we weigh about 70 kg, this becomes a meal in which we ingest about 140 g of carbohydrates. Needless to say that this is the ideal and is where we have to tend to, it is theoretical and must be adapted throughout the season to it.

Last but not least, we must pay attention to our hydration. The day before the competition we must make sure to get a correct water intake and already concretely the hour and a half before the competition to drink a liter of water in small sips.


As we are estimating that the race will last between two and five hours, we are going to divide the race into three theoretical competition times:

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Mark between 2 and 3 hours: we are in very fast times, in which during the competition we are going to have time to take small sips of water and it would not be necessary to consume more than 500-600 ml of water the hour (depends on external conditions, sweating…). As for food, after an hour and a half of competition we should introduce 30 grams of carbohydrate quickly absorbed (through an isotonic, gels, white bread …).

Mark between 3 and 4 hours: as for hydration, always in small sips we should consume at least around 500-600 ml of water per hour.

From minute 0 to 90: only water is enough, if possible mouthwashes with an isotonic at the end of the stretch.

From hour and a half to 2 hours and a half: in this hour we should consume about 30 grams of carbohydrate of fast absorption (through an isotonic, gels, white bread…).

From 2 hours and a half to 3 hours and a half: in this last hour the rate of carbohydrate consumption increases to about 60 grams.

Mark between 4 and 5 hours: we would follow the same indications as in the previous section, only that in the last hour we should at least continue with this rhythm of 60 grams of carbohydrate of fast absorption. This indication is theoretical, it is a large amount of food during exercise and this has had to be trained previously in the season to tolerate it.

These indications should never be tried for the first time in a competition, as your body will most likely reject it.


In such long races, the depletion of muscle glycogen reserves and dehydration are two factors that will limit our body’s recovery.

Therefore, we will have to take advantage of the two hours after the competition, which is where the muscle is more sensitive to recover that glycogen. We call this the anabolic window, which means that in those two hours post-exercise we are interested in taking in carbohydrate because we will recharge the lost glycogen much better than if we do it at dinner (having competed in the morning, for example).

The amounts of carbohydrate we are talking about are around 1 g of carbohydrate per kilogram of body weight, during the 2 hours after exercise. Weighing 70 kg, it would be 70 g of carbohydrate in the 2 hours after exercise. You can always ask your trusted nutritionist or a diet calibrator (there are many applications for cell phones) to calculate the type and amount of food you have to eat to reach these requirements.

Nor can we forget hydration: along with that carbohydrate we will introduce at least half a liter of water per hour, always drinking little by little.

Finally, we would like to remind you that these nutritional tips go hand in hand with a good race preparation, with scheduled outings according to your level and goals, as well as specific strength training for runners.