Scientists from the Max Planck Institute have discovered in mice a network of neurons that literally “turns off” the feeling of hunger - immediately after the animal smells food. But in obese mice this mechanism does not work. The work is published in the journal Nature Metabolism.

The researchers found a new group of nerve cells in the medial septum of the brain that is directly connected to the olfactory bulb, the first odor-processing node. As soon as a mouse picks up the flavor of food, the neurons are activated and trigger the sensation of satiety. By themselves, however, tastes and odors not associated with food do not trigger this response.

“This is most likely an evolutionary mechanism,” explained study author Janis Bulk. - In the wild, a mouse that eats quickly and leaves has a better chance of not being caught by a predator."

But in obese mice this mechanism is disabled: the smell of food does not cause the activation of neurons, and they continue to eat in the usual volume. The researchers note that obesity itself can disrupt the olfactory system - including a new group of neurons.

Humans have these neurons, too. What's more, some studies show that certain odors before meals reduce appetite - but only in slim people. In obese people, odors, on the contrary, increase hunger. The new discovery may explain why.

"We now know that the sense of smell plays a key role in appetite regulation. And if the smell of food triggers satiety in some people and not in others, it means that the approach to preventing overeating should be individualized," added Sophie Stekulorum, the study leader.