Body weight: “It’s the brain that’s the boss”

Humans have much less control over their body weight than they think, according to a study by a research team from Laval University and the IUCPQ Research Center, which reveals that the brain plays an important role in relation to the figure indicated on the scale.

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Strict diets, diets, physical exercise and the good will of those who wish to lose weight might be of very little use, according to the study led by Benoît Arsenault, professor at the Faculty of Medicine of Laval University and researcher at the IUCPQ.

This study demonstrated that genetic regions associated with body mass index (BMI) influenced the concentrations of several proteins expressed in the brain and that genetic factors might explain up to 50-75% of the variance in BMI. in the population.

• Listen to the interview with Benoît Arsenault, professor at the Faculty of Medicine at Laval University and researcher at the IUCPQ on Sophie Durocher’s program broadcast live every day at 2:35 p.m. via :

It was already known that several hundred genetic regions that influenced body weight, but their functions still remain unknown to this day.

The team therefore focused on a region that notably influences sensitivity to the feeling of reward associated with food intake. This region of the brain, called the dorsolateral prefrontal cortex, would also influence the regulation of appetite and satiety.

“It was not known which proteins had a role to play in the differences in weight from one person to another. So we, with genetic analysis techniques, were able to identify around sixty of these proteins,” explains Mr. Arsenault.

Courtesy Benoît Arsenault

Benoît Arsenault, professor at the Faculty of Medicine of Laval University and researcher at the IUCPQ

Laziness, a myth

The discovery establishes that the identified genes encode proteins that would influence body weight via their expression in the brain.

With these results, the study shatters the myth of the person who is overweight due to lack of willpower and laziness. The researcher points out that most people living with overweight who have tried dieting have not had the expected results and that “it’s the brain that’s the boss”.

“We think our study may partly explain why these diets don’t work. […] there are neurobiological mechanisms that will prevent this weight loss, ”says Mr. Arsenault.

Next, the researcher will seek to establish the exact function of these proteins and on which biological systems they exert an influence.

“Because weight is not just food intake, but also energy expenditure in a day, sleep – which plays an important role in weight – and stress management,” he adds.