Do you diet, lose weight, but then a night out is enough and you gain a pound and a half? Or despite doing everything right in the maintenance diet, do you resume gradually returning to the previous weight? Well, the body’s ability to re-gain weight, causing the infamous yo-yo effect could be caused by a protein, Crat, which is activated by the brain by controlling hunger and satiety hormones, thus in response to activity of the hypothalamus. This protein , whose full name is Carnitine Acetyl Transferase , acts as an enzyme in the metabolism of carnitine, and according to a recent study by Monash University, it also acts as a mediator of metabolic flexibility .

Put simply. When we eat less and are in a calorie deficit, the body uses fat for energy, in the absence of an adequate energy supply provided by the diet. So, in theory we lose body fat and lose weight, because the body empties the adipocytes (fat cells) as an energy function. When we go back to eating, if we have good metabolic flexibility, the body should harness the energy of the food we give it to live , allowing us to remain the weight we have laboriously achieved. But alas, it happens instead that the body instead of using what we eat for a living, sets it aside in the form of body fat , and more easily than before the diet. This mechanism is generally explained by talking aboutmetabolic slowdown caused by diet. But now the researchers explain exactly what happens, which is why evolutionally speaking, when we go back to eating after a period of prolonged calorie deficit, the body tends to put on more weight . The reason lies precisely in the activation of this protein: by manipulating it, it is possible to have a better metabolic flexibility and not to regain the weight lost.

The interesting thing is that according to the researchers , when the body perceives the calorie deficit, a whole series of defenses are activated to limit it, for example by consuming as little energy as possible. Hence, the slowing of the metabolism. When you go back to eating, no matter if with just one free meal, with a day off or refeed, or with a maintenance diet, the body accumulates fat more easily. This explains why many people fail to stay at the right weight after a diet:there are those who have maintained greater metabolic flexibility, with a body that adapts to the free meal, the cheat or the new maintenance diet. And who, and most of us are, because of the diet has impaired metabolic flexibility: the body does not use food for energy, but retains a part of it. This happens in the same area of ​​the brain that regulates hunger and satiety.
What does it mean?
1) That when we are in a calorie deficit the metabolism is always and in any case lowered , especially if this deficit is imposed. It is one thing not to be naturally hungry and eat more in the following days: this has always been a self-regulation system typical of thin people. Another is going on a diet.
2) That the only way not to lower the metabolism is to not diet. 
3) That a useful way to lose weight might rather be to regulate our metabolic flexibility and not follow a restrictive diet. I’m talking about it here: how to improve metabolic flexibility .