That burning desire for french fries that strikes you every time you drive past a Jack-in-the-Box or McDonald’s may not just be a lack of will power. According to a new study, high-fat, high-calorie foods may affect the brain in much the same way as cocaine and heroin. Junk food, like cocaine, gradually overloads the “pleasure centers” in the brain, according to Paul J. Kenny, Ph.D. lead author of the study and associate professor of molecular therapeutics at the Scripps Research Insititute, in Jupiter, Florida. Eventually these pleasure centers break down, which means that getting the same kick from your substance of choice, or even just feeling normal, means you need more of the drug or food.
“People know intuitively that there’s more to [overeating] than just willpower,” he says. ”There’s a system in the brain that’s been turned on or over-activated, and that’s driving [overeating] at some subconscious level.” The rats in Kenny’s study showed their devotion to their fatty addiction – eating despite pain stimulus that drove rats who were fed a healthier diet away from the food bowl and even going on a hunger strike when their food was swapped out for healthier fare.
The neurotransmitter dopamine, which is a key to how the brain rewards the body in order to reinforce behavior, seems to be responsible for the addictive behavior of Kenny’s overeating rats. Overeating causes the levels of a particular dopamine receptor in the brain to drop. In humans, low levels of the same receptors are often related to drug addiction, obesity and may be genetic.
