70% of the weight variabilities between individuals may be attributable to genetics.
One in five adult Quebecers is considered obese, with a body mass index (BMI) of 30 or above. According to Uku Vainik, postdoctoral researcher at the Montréal Neurological Institute and Hospital – The Neuro, this excessive weight gain is largely controlled by an individual's brain.
He analyzed the cognitive test results and magnetic resonance images of 1 200 overweight patients and noted marked differences between their brains and the brains of subjects with a BMI within the normal range (between 18.5 and 25). The researcher found that people suffering from obesity have a thinner right prefrontal cortex and larger left amygdala: two characteristics that could trigger a greater response to food stimuli. In addition, these individuals demonstrate less cognitive flexibility and have a more difficult time delaying gratification, including gratification from food, than people with a health body weight.
According to Uku Vainik, genetics may modulate the brain, making it more or less sensitive to food stimuli and thus playing a role in obesity. He also observed strong personality traits in people with an above-average BMI, including food-related impulsivity.
Indeed, 70% of the weight variabilities between individuals may be attributable to genetics. But does this mean that people who are predisposed to obesity are doomed to gain weight? Uku Vainik affirms that their fate depends on their environment and lifestyle, since exercise and healthy eating habits can counter genetics. However, the opposite is also true: a steady diet of fast food will trigger the obesity genes.
The findings stress the importance of weight control through exercise and healthy eating, as well as with the support of cognitive and behavioural therapies to make the right choices, stay away from junk food and better resist the temptation to eat.