Junk Food May Cause Changes to the Brain: No More Balanced Diet

We all know that junk food isn't good for us. But did you know it actually may cause lasting changes to the brain? Scientists have found that a diet of junk food not only makes rats fat, but also reduces their appetite for novel foods, a preference that normally drives them to seek a balanced diet.

In order to understand the impact of junk food, the researchers taught young male rats to associate each of two different sound cues with a particular flavor of sugar water-cherry and grape. They found that healthy rats that were raised on a healthy diet stopped responding to cues linked to a flavor in which they had recently overindulged.

Yet after two weeks on a diet that included junk food, with about 150 percent more calories, their behavior changed dramatically. The scientists found that the rats became indifferent in their food choices and no longer avoided overfamiliar tastes. This indicated that the rats had lost their natural preference for novelty. In fact, the change lasted for some time after the rats returned to a healthy diet.

"The interesting thing about this finding is that if the same thing happens in humans, eating junk food may change our responses to signals associated with food rewards," said Margaret Morris, the lead researcher, in a news release. "It's like you've just had ice cream for lunch, yet you still go and eat more when you hear the ice cream van come by."

The findings reveal that junk food may cause those already suffering from weight issues to gain even more weight. As the obesity epidemic continues, it's more important than ever to turn to healthier foods in order to slim down.

The findings are published in the journal Frontiers in Psychology.