We'll often opt for french fries over a side salad because our brains implicitly value higher-calorie foods, according to a new study conducted by researchers at McGill University and the Montreal Neurological Institute.
The researchers asked participants to determine how much they would pay for various junk foods like chips and candy, as well as for healthier foods including vegetables. The participants had never dieted before, so many of them were unaware of how many calories the foods actually had, but they reliably were willing to pay more for the higher-calorie foods.
We learn this through experience, explained Alain Dagher, neurologist at the Montreal Neurological Institute and Hospital in an interview with Yahoo Health. When you eat, nutrients make their way through your bloodstream to the brain. "Our brains learn what nutrients are present in the foods we consume. This is necessary, because humans are omnivores -- we eat all kinds of things. So our bodies have to tell us what we need so that we shape our diets."
Yahoo Health reports:
When you're making food choices -- say, between chocolate cake and celery -- an area of the brain called the ventromedial prefrontal cortex weighs in. "It's the part of the brain that calculates value," said Dagher. When the researchers performed brain scans on the people bidding on foods, this region lit up. "In our study, that area of the brain tracked caloric density," he said. "This suggests that the caloric density of food is what determines the value." Read: This part of the brain is not considering vitamin C or protein -- it's focused on getting the most caloric bang for your buck.
"If you come across a plentiful food supply, you can consume that food now, store the calories as fat, and then you'll have them to burn later on," Dagher continued. "This was advantageous until maybe 30 years ago. It's only recently that we have very cheap food year-round."
That's why dieters still sometimes have trouble making good food choices -- preference for heartier food is hard-wired into our unconscious processing. While there are many factors to the obesity epidemic, Dagher and the other researchers chose to focus on one: "Obesity is a problem of choice," said Dagher. "We need to think of the brain as being central to obesity."