Next time you reach for that jelly doughnut or bag of Doritos, your brain might be just as vulnerable as your waistline.

In a recent study published in Frontiers in Psychology, a group of researchers in Australia fed rats a variety of junk food (and only junk food) for a two-week period. As expected, the rats gained a considerable amount of weight but what was also found is that when presented with new and healthier foods, the rats politely declined them.

Among other traits that make up a healthy individual, having a diverse diet while eliminating junk foods is among the top two along with a daily exercise regime. According to the study, their theory is that when a human is stuck in a cycle of junk food and only junk food, that person not only gains excess empty calories but also slowly shuts themselves off from healthier food options like fruits and vegetables.

In order to test their theory, the researchers put rats on an unhealthy diet of high-fat foods consisting of 150 percent more calories than what is considered a healthy diet. After two weeks the rats became indifferent to other foods and preferred to only eat the unhealthy sugar water that they had indulged in for the previous 14 days.

Researchers then forced the rats on a healthy diet, but when given the option to go back to the unhealthy diet the rats preferred the sugar water yet again, proving that unhealthy junk food options can have a similar effect on the brain that addicting drugs have.

"Our current findings demonstrate that exposure to obesogenic 'cafeteria' diets disrupt both the expression of sensory-specific satiety and stimulus-outcome associations," says the report.

"These observations are of importance in the understanding of how obesity may impact upon the processing of appetitive outcomes and associated stimuli, and also to how maladaptive associations may control food seeking behavior in the absence of physiological and homeostatic requirements."

Currently, over 80 million Americans suffer from obesity, according to the Centers for Disease Control and Prevention and have an estimated increase of $1,500 a year per person in health care costs due to obesity-related health problems.

Ultimately, not only is junk food unhealthy for your waistline and wallet, it is also a dangerous psychological merry-go-round that can be difficult to get out of.

If you believe you may have a problem with overeating, you can call the Overeaters Anonymous hotline at 1-505-891-2664.