Why Your Brain Makes You Reach for Junk Food

New study examines link between brain cortex and food buying habits.

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.”

This image shows the outline of a person surrounded by fast food icons. In the head space is the outline of a brain in purple.
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. This image is for illustrative purposes only. Credit NeuroscienceNews.com.

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.

Notes about this psychology research

This work was funded by the Canadian Institutes of Health Research.

Contact: Anita Kar – McGill University
Source: McGill University press release
Image Source: The image is adapted a public domain image by johnhain. Credit NeuroscienceNews. We release this image into the public domain
Original Research: Abstract for “Behavioral and Neural Valuation of Foods Is Driven by Implicit Knowledge of Caloric Content” by Deborah W. Tang, Lesley K. Fellows, and Alain Dagher in Psychological Science. Published online October 10 2014 doi:10.1177/0956797614552081

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