"Obesity is the result of behavior that involves excessive calorie consumption, and we've found that (behavior) comes from the brain," says researcher Alain Dagher.
Serious weight gain is largely controlled by the brain, suggests a study by a team from the Montreal Institute of Neurology.
One in five adults in Quebec is obese – a condition determined by having a body mass index (BMI) above 30.
By analyzing the results of cognitive and magnetic resonance imaging tests carried out on 1,200 overweight individuals, researchers Uku Vainik and Alain Dagher from the Montreal Neurological Institute found significant differences in the brains of the subjects compared to those who retain what was defined as a normal BMI between 18, 5 and 25
The study showed that the right prefrontal cortex is thinner and the left part of the amygdala is larger in the brains of overweight people, which, according to research, promotes a more intense response to stimuli provided by food.
According to the study, people who are overweight have less cognitive flexibility and a reduced ability to resist pleasure (such as that provided by food) than people who maintain a normal body weight range.
"Obesity is the result of behavior that is excessive calorie intake, and we've found that (behavior) comes from the brain," said Dagher.
The study also examined members of the same family as well as twins, which allowed scientists to note that 'these factors in the brain can be inherited'.
"So it's probably due to genetic factors," said Dagher. "We can inherit this susceptibility to overeating."
The situation is aggravated by what the study describes as an "obese" environment that makes extra calories easily available to those who overeating.
However, as is often the case, genetics do not tell the whole story. And those whose brains seem ready to be eaten and obese do not necessarily have to be overweight.
"Nothing is really predetermined," said Dagher. "We're just talking about influences. We know that 70 to 80 percent of your weight variation comes from genetics. However, when people do a lot of physical activity, (impact) drops to 30 percent.
"This behavior – physical activity – can eliminate or significantly reduce the genetic effect."