(Montreal) Body weight is essentially decided in the brain and we have only a limited ability to influence it, seem to demonstrate work carried out in Quebec.
Researchers from Université Laval and the Center de recherche de l’Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval have thus identified some sixty proteins expressed in the brain that could exert a positive or negative influence on body weight. .
“When you look at where genes that contain genetic variations that are associated with weight are expressed, most of the time you would think, for example, that they are expressed in certain tissues, like our adipose tissue, in our reserves of fat,” said study leader Professor Benoît Arsenault.
“But in the end, that’s not the case at all. By far the organ in which the genetic variants associated with weight are expressed is the brain. »
The researchers unearthed these proteins by cross-referencing the genetic profiles of some 800,000 people of European descent with databases of protein expression in the brain. The 60 substances identified, Arsenault said, is a “conservative” number.
The researchers focused more specifically on the dorsolateral prefrontal cortex, a region of the brain that would influence, among other things, the sensitivity to the feeling of reward associated with food intake, such as the feeling of pleasure in eating a fatty or sweet food, a-t- specified in a press release.
This region would also play a role in the regulation of appetite and satiety as well as in certain cognitive functions such as decision-making and memory.
“It’s the brain that controls our food intake, it’s the brain that will control the feeling of satiety, after taking a meal it’s our brain that will tell us when to eat, it’s our brain that will tell us when to stop eating, it is our brain that will perceive signals in our environment that are associated with food intake, smells, memories that we have in relation to certain moments that we have been able to spend, for example in some restaurants, etc. Our brain controls us,” Arsenault said.
Genetic factors could therefore explain 50% to 75% of the variance in body mass index, or BMI, in the population. This could partly explain why BMI varies significantly from person to person.
This discovery sheds new light on the interaction between the brain, weight and the environment.
We thus see that individuals who have a genetic predisposition to be overweight have a higher weight than before, while individuals who do not have this predisposition were thin before and are still thin today, explained the professor. Arsenault.
Experts now have the necessary data to scrutinize the evolution of the situation. They find that, in the 1960s and 1970s, the body mass index of people who had a genetic predisposition to be overweight was not so high.
“But today,” Mr. Arsenault said, “(their BMI) is much higher than before, so we’re really talking about an interaction between our genes and our environment. »
And it’s not just about the food environment, he reminds: stress, lack of sleep, accumulation of screen time and physical inactivity are all factors that will have an impact on weight. bodily.
It also further debunks the myth that overweight people are overweight because they’re lazy or unwilling, he said, since “unconscious neural mechanisms” are at play.
“I think the study shows that we have a lot less control over our body weight than we think,” Arsenault said. So indeed, for people who are going to make attempts to lose weight, for the vast majority […] it can work over a few weeks, a few months even. But in the long run, most of the time, it doesn’t work. »
The proteins identified by Arsenault and his team may one day be modulated to influence patient weight, either by reducing the effect of those that promote weight gain or by increasing the effect of those that have the opposite effect . Some drugs already used for weight loss act on the brain, but it is not known whether their effect passes through these proteins.
The findings of this study were published by the scientific journal iScience.