Le jeûne : une pratique réellement bénéfique pour la santé ?

Fasting: a truly beneficial practice for health?

Aug 04, 2023

This is one of the new fad diets. Reflecting a society more concerned about its health, sometimes going against the grain of a system of overconsumption, fasting is gradually gaining popularity . New revolutionary treatment, elixir of youth... So many formulas which are now used to extol the merits of this practice. However, given its exponential scale, it remains important to ask questions. Regardless of fashion and the abundance of information of all kinds, demonstrating critical thinking is a fundamental issue. So, is fasting really good for your health? What are its impacts?

Fasting, what is it?

Before getting to the heart of the matter, it is important to understand what we are talking about. Indeed, even if this notion is now known to everyone, it is not always well defined. According to Inserm, “complete fasting consists of abstaining from all food (solid and liquid), with the exception of water, for a more or less long period”. In practice, two categories of applications nevertheless emerge.

1- Chronological fasting

This type of fast consists of total food restriction over a given period. Among the most popular, we can of course cite intermittent fasting . Its practice is not uniform. Indeed, it can be done in different ways: not eating for 6, 10, 12 hours, a full day once or twice a week, etc.

2- Qualitative fasting

This second category consists of a deprivation of certain types of food , regardless of the time of intake. These include total fasting (which consists of total deprivation of food), dry fasting (which is deprivation of food and water) and food restriction, that is to say eating only one or a certain type food only. Providing a binary response to the benefit of fasting is therefore not possible. Depending on the category, the duration, but also the individual character of each person, the conclusions can only be different .

Read also: Nutritional needs: what should you remember?

The benefits

Common beliefs around the benefits of fasting mainly revolve around two main axes: physiological and psychological benefits. To investigate this societal fact, scientific research was carried out.

On a psychological level, the practice of fasting would improve the feeling of well-being, in particular thanks to the secretion of endorphins. On a physiological level, fasting has countless benefits.

Among them, we find in particular :

  • Stimulation of the immune system.
  • Metabolic changes including cholesterol limitation.
  • The regulation of hormonal secretions such as reducing insulin levels.
  • The detoxifying function; Fasting would allow excess water to be evacuated due to overconsumption of salt in the short term.
  • Reducing the risk of developing chronic diseases such as cardiovascular diseases.
  • Modification of the intestinal microbiota.
  • The most effective fight against inflammatory diseases . To justify this phenomenon, it is necessary to know that chronic inflammation is favored by excessive caloric intake. Fasting therefore makes it possible to reduce the symptoms of a chronic inflammatory disease without preventing a normal inflammatory response (in the case of anti-infectious reactions).
  • Delaying aging , reducing the risk of age-related diseases, extending life expectancy, cell regeneration.

However, and despite the fact that some studies obtain promising results, everything still remains to be proven firmly and definitively. Indeed, to date, scientific studies carried out in humans are not sufficiently numerous and rigorous to conclude that it is therapeutic or preventive.


Regardless of the actual or potential benefits, it is important to realize that fasting has limitations .

First, fasting is known to promote weight loss . However, be careful about stopping this type of diet suddenly; the risk of rapid weight regain ( yoyo effect ) is considerable. Moreover, in this logic of being more progressive than brutal, numerous research suggests that following a balanced, low-calorie diet would potentiate the effects of fasting...

Unfortunately, these risks are far from the only ones that can be listed. Initially, you may notice that headaches may occur, as well as dizziness which may lead to discomfort. In addition, there is a risk of deficiency : these deficiencies often prove counterproductive because they impair organic functions and promote muscle wasting. In the long term, an iron deficiency can lead to anemia. Far from being trivial, fasting also carries risks of degradation of the bone capital, of developing heart rhythm disorders, inflammation and hepatic fibrosis...

Alongside these risks, it is important to keep in mind the unique nature of each individual. For example, the risks will be different if it concerns elderly people, pregnant women, etc.

The time factor plays a major role in the benefits of fasting. Between a long or short term practice, the impacts will be different. For example, we talked about the detoxifying function of fasting. Yes, but in the short term. Indeed, over a longer period, the body with food restriction acidifies and produces toxins. It can also, in addition to storing in fat, store in muscle mass.

We must therefore keep in mind that fasting is not trivial. Although there is talk of real or potential benefits, too few clinical trials have actually been carried out. This practice must therefore remain supervised in order to limit the risks by ensuring, for example, that there are no contraindications.

References :

Radio France. (April 21, 2021). Is fasting good for your health? https://www.radiofrance.fr/franceculture/podcasts/les-idees-claires-le-podcast/le-jeune-est-il-bon-pour-la-sante-8755962

Ministry of Health and Prevention. Fasting for preventive or therapeutic purposes. https://sante.gouv.fr/IMG/pdf/fiche_jeune.pdf

Inserm. (January 10, 2014). Evaluation of the effectiveness of the practice of fasting as a preventive or therapeutic practice. https://www.inserm.fr/wp-content/uploads/2017-11/inserm-rapportthematique-evaluationefficacitejeune-2014.pdf

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