The famous nutritionist is clear: one method gives much better results than the others.
Intermittent fasting continues to appeal to those who want to lose weight without counting every calorie. The promise is simple on paper: play on schedules rather than permanent restrictions. But behind this idea, several formats coexist and they do not produce the same effects. Jean-Michel Cohen recently took stock by clearly distinguishing three options.
In an Instagram video, he explains: “There are three types of fasts: the 16-hour fast, the 20-hour fast and the 24-hour fast.” These durations correspond to periods during which no caloric intake is authorized. The principle remains the same: alternate eating phases and non-eating phases in order to encourage the body to draw on its reserves. Many spontaneously think that the longer the fasting period, the greater the weight loss will be. However, according to the nutritionist, the observations do not point in this direction.
He states in fact: “In fact, experimentally, the one that works best is the 16-hour fast. I’m talking to you on a physico-chemical level. That means that we found that the 16-hour fast mobilized fats more, yes yes it’s surprising than a 20-hour fast or a 24-hour fast.” Indeed, after several hours without eating, the body begins to use fat more as a source of energy. But the important thing to remember is that prolonging deprivation does not necessarily mean optimizing the process.
Concretely, after a dozen hours without caloric intake, the body gradually switches towards a more marked use of fats. The 16-hour window makes it possible to reach this pivotal moment and maintain it long enough for fat mobilization to be truly active. With longer durations, the body will slightly slow down its energy expenditure and increase hunger at the next meal, complicating the overall regulation of intake.
Conversely, a shorter fast does not always allow time to fully enter this phase of increased lipid use. The 16/8 format therefore creates an intermediate zone where fat burning is effectively stimulated while maintaining a food organization compatible with daily life, promoting regularity and, ultimately, results on the scale.
However, Jean-Michel Cohen warns against a common error: “The 16-hour fast is practiced provided you have a controlled diet during the 8 hours allowed to eat, if you want to lose weight. If you don’t do that, you will have no results.” The authorized time slot must therefore not become a time for compensation. The quality and quantity of food remain decisive in creating an energy deficit.
