WHY YOUR BRAIN MAKES YOU REACH FOR JUNK FOOD
Will that be a pizza
for you or will you go for a salad? Choosing what you eat is not simply a
matter of taste, conclude scientists in a new study at the Montreal
Neurological Institute and Hospital of McGill University and the McGill
University Health Centre. As you glance over a menu or peruse the shelves in a
supermarket, your brain is making decisions based more on a food's caloric
content.
The
study, published in Psychological Science,
is based on brain scans of healthy participants who were asked to examine
pictures of various foods. Participants rated which foods they would like to
consume and were asked to estimate the calorie content of each food.
Surprisingly, they were poor at accurately judging the number of calories in
the various foods, but their choices and their willingness to pay still
centered on those foods with higher caloric content.
"Earlier
studies found that children and adults tend to choose high-calorie food"
says Dr. Alain Dagher, neurologist at the Montreal Neurological Institute and
Hospital and lead author of the study. "The easy availability and low cost
of high-calorie food has been blamed for the rise in obesity. Their consumption
is largely governed by the anticipated effects of these foods, which are likely
learned through experience. Our study sought to determine how people's
awareness of caloric content influenced the brain areas known to be implicated
in evaluating food options. We found that brain activity tracked the true
caloric content of foods."
Decisions
about food consumption and caloric density are linked to a part of the brain
called the ventromedial prefrontal cortex, an area that encodes the value of
stimuli and predicts immediate consumption.
Understanding
the reasons for people's food choices could help to control the factors that
lead to obesity, a condition affecting 1 in 4 Canadian adults and 1 in 10
children. Obesity is linked to many health problems including high blood
pressure, heart disease and type 2 diabetes. Treating Canadians who have these
problems costs billions of tax health dollars.
This
work was funded by the Canadian Institutes of Health Research.
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