A new scientific study would appear to suggest that over-eaters are not necessarily pushed into eating more by their stomachs, but by their brains. The investigation, which was conducted on unsuspecting rats, proved that the brain chemistry of over-eaters and drug addicts was very similar, which sheds new light on the problem. Drug addicts, alcoholics and smokers all have the same type of brain chemistry, which prevents them from quitting their habits, except with great difficulty. The new research on rodents proves that the same type of difficulties also appears in the case of plain food, when it comes to something you like, LiveScience reports.

“For people who are eating way beyond their need and storing excess fat, there's a debate as to whether you want to call that a disorder of the brain,” the Director of the University of Pennsylvania School of Medicine Center for Studies in Addiction, Charles O'Brien, says. He is also a member of the team that is editing the new Diagnostic and Statistical Manual of Mental Disorders, or DSM, which will classify a large number of conditions according to new studies. Psychiatrists use the DSM for guidelines in diagnosing their patients, and conditions such as anorexia and bulimia are already included.

The new research also gives further support to the idea that those who overeat can be considered addicts, similar to those involved in drug use or gambling. However, the idea is questioned among scientists, and there are those who advocate against overeating being included in the new version of the DSM. In the study, experts at the Boston University Laboratory of Addictive Disorders, led by Co-directors Pietro Cottone and Valentina Sabino, showed that giving rats unhealthy food altered the same regions of the brain as the one modified when giving them alcohol, nicotine and opiates.

In the experiments the team set up, the regular diets of a number of rats were changed, and they were given unhealthy, sugar-rich food instead. After 48 hours on the new diet, they were switched back to their regular chow. The rodents showed very little interest in the healthy food, and generally ate a lot less than their comrades that had never tasted sugary nourishment. Cottone reveals that the same type of behavior is also seen in people switching between healthy and unhealthy diets.

Furthermore, the team identified the fact that the rats' brains were “punishing” them for moving off the sugary stuff. Their amygdala, a region of the cortex involved in controlling fear and anxiety, released five times the usual amount of the protein corticotropin-releasing factor, or CRF, which is normally produced in the brains of addicts trying to quit their vice. “This [CRF] punishment, this negative enforcement is causing anxiety and is increasing the probability that bad behavior is performed in the future to relieve anxiety,” Cottone explains.