Recent techniques make it possible to study in detail the molecular changes that occur following food deprivation over a long period.
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Twelve participants completed a seven-day water fast.
Alain Labelle (View profile)Alain Labelle
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While intermittent fasting has gained popularity in recent years for aesthetic reasons, especially to lose weight, humans have been fasting since Antiquity for sociocultural, religious and medical reasons.
But medicine knows little about what happens in the body during food deprivation, beyond the fact that the energy necessary for the body to function is produced less and less by the calories consumed and by increasingly by stored fats.
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In the study , participants drank only water for 7 days.
Professor Claudia Langenberg from Queen Mary University of London and British and European colleagues wanted to understand what happens in the body during food deprivation. /p>
To achieve this, they followed 12 healthy participants who completed a seven-day water fast. A young water person means completely stopping eating and consuming only water, explains Professor Benoît Arsenault of Laval University, a specialist in cardiometabolic diseases, who did not participate in the work.
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In their work, the authors recorded changes in the levels of approximately 3,000 proteins in their blood before, during and after fasting.
For the first time, we have been able to see what happens at the molecular level in the body when we fast, says Claudia Langenberg, the lead author of the study published in Nature Metabolism (New window) (in English).
By identifying proteins involved in the body's response, researchers were able to predict the potential health effects of prolonged fasting by integrating genetic information from other studies. They estimated that 212 blood plasma compounds were modified during fasting.
For example, the researchers observed that a fast of more than three days leads to the decrease of a certain protein in the blood; this could reduce the risk of rheumatoid arthritis.
This finding provides a beginning of an explanation for the observed relief of pain in people with polyarthritis during fasting.
Researchers also detected negative effects associated with fasting. For example, they observed an increase in a clotting factor which would increase the risk of thrombosis.
For the first time, researchers observed that the body experiences distinct changes in protein levels after three days of fasting, indicating a whole-body response to complete calorie restriction. In other words, the health benefits only seem to occur after three days of food deprivation.
It's later than previously thought.
A quote from Claudia Langenberg, the main author of the study
Professor Arsenault of Laval University considers the study robust and interesting, even if it was only carried out with only 12 people.
I am usually the first to think that it takes large long-term studies carried out with tens of thousands of people to arrive at convincing results, remarks the professor who judges that in the case of this metabolic study, twelve people is x27;is more than enough.
With extreme protocols like that of this study, we do not need to have many participants to observe significant differences, adds Benoît Arsenault. I would have liked to see a control group, but I think the protocol is so intense that it is clear that the changes observed are due to the seven day calorie restriction.
However, the results obtained do not surprise Professor Arsenault.
They have technologies that make it possible to measure thousands of proteins at the same time, and that’s interesting. But their results show changes in insulin levels, triglycerides, which have been known for decades.
A quote from Benoît Arsenault, Laval University
I find the study very interesting, but there is a danger in overinterpreting the observations. It's as if we had taken for granted that fasting had health benefits. For me, it's far from being so clear, specifies the professor.
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Professor Arsenault reminds us that there are several contraindications to fasting, particularly intermittent fasting, which are often practiced for cosmetic reasons.
Let's face it, people fast especially to be thin, because we live in a society that values thinness, in which the culture of diets is very damaging to people's minds.
A quote from Benoît Arsenault, Université Laval
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There are several contraindications to fasting.
The People who are chronically ill need to be very careful. Those with eating disorders who want to fast are also at risk, notes Benoît Arsenault.
The professor also notes that while the study is interesting on a metabolic and physiological level, it does not provide information on the possible benefits of intermittent fasting in particular.
In the short term, people lose fat, we don't question that!, he says. There are also benefits on high blood pressure, on insulin sensitivity in prediabetic people or in those who have a little cholesterol, who see their blood lipids decrease slightly.
According to the professor, studies show that fasting is no better than continuous calorie restriction (like diets) for losing weight.
Whether we eat our calories within a window in a day or eat a little less with each meal, there is really no added value to intermittent fasting. . It's just another way of restricting yourself. It's mathematical!
A quote from Benoît Arsenault, Laval University
There are people who say that fasting has small effects additional benefits because we align it with our circadian rhythms, but no credible study has shown this, indicates the professor.
Studies also show that it is necessary to adopt Mediterranean diet profiles. To be healthy, you must follow the recommendations of Canada's Food Guide. And it's not complicated, eat more fruits and vegetables, more fiber, more whole grain products, more plant proteins.
A quote from Benoit Arsenault, Laval University
You don't need to fast to be healthier. We must first focus on quality rather than quantity, concludes the professor.
The authors believe that their study provides a road map for future research that could lead to therapeutic interventions, including for people who might benefit from fasting, but who cannot follow prolonged fasting or fasting-mimicking diets, such as ketogenic diets.
