Training on an empty stomach

Within endurance sports, it is common for many athletes to perform training sessions on an empty stomach.

The main objective at the center of this method is the optimization of sports performance, by adapting the body to use more fat as a source of energy.

In reality, from a physiological point of view this is not the most effective solution ...

1) Physiological adaptations

During training on an empty stomach, the effort will be carried out with reduced hepatic glycogen reserves (stock of sugars in the liver), but not in the muscles.

According to the work of Dr. Fabrice Kuhn (author of the book Ultra Performance), it is the fact of having low muscle glycogen reserves during exercise, which will allow the physiological adaptations of the body to optimize sports performance in endurance.

We will then talk about low glycogen training

An example with "Sleep Low":

A high intensity session at the end of the day with optimal glycogen reserves


A dinner without carbohydrate recharge


A short, low-intensity session on an empty stomach the next morning

This type of method must be carried out punctually and introduced gradually within a structured training plan.

In a logic of progression, and in order to be fully efficient during intensity sessions, it is necessary to have a sufficient reserve of glycogen, in particular thanks to a periodization of carbohydrates according to the training schedule.

2) psychological adaptations

Simple training on an empty stomach, on the other hand, can have positive mental effects.

Indeed, performing this type of session allows us to overcome this psychological barrier of lack of food by getting used to the sensation, but also that of the fear of energy failure.

This will increase our self-confidence, proving to us our ability to adapt and make an effort without taking an energy intake beforehand.


Training on an empty stomach should not be seen as the most effective solution for optimizing the use of fat as a source of energy.

It is a leverage effect on certain points, which can be integrated into a structured planning over short and not very intense sessions.


This content has been published by our Ambassador Guillaume Klein (Personal Coach Sports nutrition and health expert / Ultra endurance specialist)
  • Nutriformation graduate specializing in micronutrition and nutritherapy
  • Trained in sports nutrition by the Evonutri Positive Nutrition Academy
  • Ultra Trail Coach trained by the Auvergne Rhône-Alpes Athletics League
  • FC Metz dietitian and nutritionist professional group (since 2018)
  • Nutritionist FC Metz training center (since 2019)

Passionate about sport, and ultra endurance athlete in running and ultra cycling, Guillaume was able to test on himself the benefits of a natural nutritional balance, appropriate to his real needs, and of a specific adapted training. Guillaume appreciates quality products which respect the nutritional needs of the athlete, but also from a health point of view, a composition as natural as possible.

You too can take advantage of his advice and find all our products on this site

If you would like more information or advice, do not hesitate to contact Guillaume via his site uses cookies to provide the best user experience. Please accept cookies to continue exploring our site
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