Why your brain makes you reach for junk food

Posted on October 21, 2014

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.

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. This 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. Obesity is linked to many health problems including high blood pressure, heart disease and type 2 diabetes.

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Source material from McGill University