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How to train your gut for racing

How to train your gut for racing

Months of preparation for your marathon, triathlon or trail race can easily go to waste if you suffer from stomach issues on the course. In this blog post, we give tips on how to eat and drink during a race and how to train your gut for the big day.


In endurance events - half marathons, marathons, trail or cycling races, triathlons - your performance comes down to not only your fitness but also what you eat and drink during the race.

Months or even years of hard work can go to waste because of poor food and drink choices. Stomach problems, such as bloating, gassiness or absorption issues, can easily ruin your race and stop you performing at your best.

The key to making your stomach your ally is to plan what you eat and drink in advance and practice your energy and liquid intake during workouts. 

This year we get to race only towards the end of the summer, so now is the perfect time to test what kind of nutrition and hydration tactic works for you and train your gut for racing. Here’s how to do it:


Enough liquid, electrolytes and carbohydrates during the race

In order to maintain your performance level, it’s crucial to get enough liquids and electrolytes. Even small dehydration can reduce your athletic performance significantly.

The right amount of hydration depends on the nature of the race, your body and the weather. Usually, you need to drink approximately 0.5-1.2 litres per hour, sometimes even more (1). Choose a hypotonic sports drink that enhances fluid absorption.

Also, carbohydrate intake during a long race will boost your performance. A common recommendation is to take (1, 3):

  • In events that last 1-3 hours: 30-60 grams of carbohydrates per hour
  • In events that last more than 3 hours: 60-90 grams per hour

However, a recent study found out that with the help of gut training, runners in a mountain race could ingest up to 120 grams of carbohydrates per hour. This proved to be beneficial compared to ingesting only 60 or 90 grams of carbohydrates per hour (4).

Especially if the amount of carbohydrates taken is over 60 grams per hour, it’s important to ingest both fructose and glucose-based carbohydrates. In Nosht energy products, the ratio of glucose and fructose is 2:1 for optimal energy absorption.


You can train your gut for racing

You prepare your body in different ways for your big race. You can also train your gut to work more effectively.

According to studies, adding glucose-based carbohydrates to your diet appears to add the amount and activity of SGLT1 proteins in the epithelial cells in the gut, which enhances the absorption of glucose (2).

You can also train your stomach to work better during sports by eating or drinking more. For example, competitive eaters practice by eating very large quantities of food as they have noticed this helps the stomach to handle large portions and empty faster.  

If you drink a lot during training, you get accustomed both physically and mentally to having a lot of liquid in your stomach (2).


Plan and test your race nutrition in your key workouts

The research isn’t conclusive on how long the period should be to train your gut to enhance carbohydrate absorption. 

For example, even a couple of days of changes in the emphasis of specific nutrients has an impact on how fast carbohydrates are absorbed (2). The athletes in the mountain race who ingested a whopping 120 grams per hour, trained their carbohydrate intake for three weeks before the race day (4).

Naturally, the adjustment period depends also on your everyday diet: if you eat a lot of carbs regularly, you’ll most likely need a shorter amount of time. But if you don’t eat carbs that much, you need to train your gut longer.

In practice, the best way to train the gut and test your race day food and drink is to simulate race day nutrition once or twice per week for a couple of months. Make the workout as race-like as possible.

In these workouts, it’s smart to use the exact products you will use in the main event. If you don’t know how much your body can ingest carbohydrates, start with smaller amounts and keep on increasing them. In less important workouts, you can also try and take a lot more energy and liquid than you usually do.


Kaisa Sali is a nutritionist and a professional triathlete who ended her career last autumn by placing sixth at Ironman World Championships at Kona, Hawaii. In Nosht's blog, she will share her expertise in sports nutrition and how to make your gut your best ally in training and racing.  



1: Burke LM, LM Castel, DJ Casa et al. International Association of Athletics Federations Consensus Statement 2019: Nutrition for Athletics. Int J Sport Nutr Exerc Metab 2019: 29(2);73-84.

2: Jeukendrup, A.E. Training the Gut for Athletes. Sports Med 47: 101–110.

3: Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med 2014: 44(1);25-33.

4: Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro, Seco-Calvo J, Urdampilleta A. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners. Nutrients 2020: 12(5); 1367.

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