Diet : we now know why there is a "yo-yo effect" !

Researchers have succeeded in limiting the yo-yo effect, or regaining the weight lost during a diet, in mice. Because it all happens in the brain. Explanations.

The yo-yo effect or yo-yo dieting is the fact of automatically regaining weight after going on a low-calorie diet during which you deprived yourself. Researchers believe they have found the cause of this curious phenomenon, and it lies in our brain.

The body in "survival" mode during a diet

Because it is not because you ingest too many calories at the end of your diet that you regain weight. This is because your body, surprised by this sudden drop in nutrients, has gone into "survival" mode. Physiological changes take place during this period of restriction, but once it is over, the body will restock to prepare for any new shortage.

Researchers from the Max Planck Institute in Germany and Harvard Medical School in the United States wanted to know precisely what was going on in our brains to trigger this yo-yo dieting effect. According to their results published in the journal Cell Metabolism and relayed by a press release, all this is the work of a group of neurons that push us to regain the lost weight.

The specialists observed the changes in the brain circuits of the mice put on a diet. It turns out that their AgPR neurons, located in the hypothalamus, a region of the brain that plays a role in controlling the feeling of hunger, are activated by other neighboring neurons, which wake up during a loss of weight caused by calorie restriction. In short, this situation creates a stimulation of our appetite, and induces weight gain.

Towards a miracle solution ? Maybe not

The worst part is that this modified cerebral communication that makes us hungrier does not stop with the diet, but can settle in over time. But these discoveries may well allow scientists to develop a solution to this phenomenon. They succeeded in inhibiting the neural pathways responsible for this feeling of hunger in mice, which made it possible to limit their post-diet weight gain. "In the long term, our goal is to find therapies that would help maintain the body weight achieved during a diet," says Henning Fenselau, researcher at the Max Planck Institute and author of the study. "To get there, we will continue to explore ways to block the mechanisms that enhance this neural pathway in humans." It is still necessary to ensure that this solution highlighted in mice can be the same in us. In the meantime, there is no miracle solution : avoid diets, prefer a balanced diet, and physical activity.