Is it really possible to lose weight while you sleep?

The omnipresent presence of fast food in our daily lives is one of the main factors responsible for the epidemic of weight gain that is currently affecting our society. We are exposed to an incredible amount of food products laden with sugar and fat (and thus calories): in the countless junk foods that have invaded our lands, of course, but also in places that normally have nothing to do with food like gas stations.

The wide availability of these high-calorie synthetic products, combined with the constant hype, means that a large number of people are eating far more than necessary and accumulating excess weight at the same time.

If the waist circumference of the population has increased significantly in recent decades, this is not due to any lack of will or laziness; It is above all a result of the “obesogenic” environment in which we live, which encourages us to eat at any time of the day, no matter where we are.

Enough for 8 to 12 hours without swallowing anything

A direct consequence of this abundance of food is a change in the structure of meals: instead of eating three times a day, it has become more common to “eat” a small snack at any time, even in the late evening. According to a recent study, consuming these snacks throughout the day can significantly contribute to weight gain and obesity.

For example, if rats can feed their advertising fame at any time in 24 hours a day, they quickly gain weight and become metabolically unhealthy (prediabetes).

On the other hand, when animals eat the same amount of calories, but for a shorter period (8 to 12 hours), they remain lean and healthy, even when that food is rich in sugar and fat.

In other words, it is not only the total amount of calories eaten that is responsible for weight gain, but also the period of time during which the meals are distributed.

The gut flora has its turn, too

How do we explain that a simple 12-hour fast can make a difference in fat accumulation?

According to a study by the same research group, this protection is due to the beneficial effect of fasting on the circadian rhythms that govern our metabolism. The gut microbial flora is particularly sensitive to these fasting/feeding cycles and it appears that the nocturnal fasting period was able to restore the microbial diversity necessary for the metabolism of food consumed during the day.

For example, scientists noticed that obese mice had an unbalanced bacterial flora, but the simple fact of exposing them to a 12-hour fast restored the microbial balance and at the same time improved their metabolic efficiency.

In other words, the way we absorb the energy in food is greatly influenced by the microbial flora, and a fasting/eating cycle that repeats every 12 hours is absolutely necessary to maintain the proper functioning of these flora.

To stay slim, it is absolutely essential to respect the complexity of our biological clock and to avoid eating anything at any time. Especially avoid snacks before bed!


Chucks et al. Time-restricted feeding is a preventive and curative intervention against various nutritional challenges. Metab Cell 20:991-1005.

Zarrinpar A et al. Diet and nutrition pattern influences the daily dynamics of the gut microbiome. cell metab. 2014; 20: 1006-17.

Also Read: Fasting and Calorie Restriction Boost Metabolism

* Presse Santé strives to impart medical knowledge in a language accessible to all. In no way can the information provided replace medical advice.

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