We already know how junk food makes you lazy. Now, new research suggests high-fat, high-calorie, sugary foods may actually discourage you from trying new foods.
In fact, salty, fatty, sugary foods may rewire the brain’s reward mechanism, rendering them as addictive as some narcotics.
In a report published in Frontiers in Psychology, researchers describe how rats given a junk food diet seem to lose all interest in other types of food. This works against the natural structure of the brain, which is wired to seek out a diverse diet and to avoid overeating. Not surprisingly, this leads to unhealthy eating habits as well as weight gain.
Half of the rats in the study were fed a high-calorie “cafeteria” diet consisting of cookies, pies, dumplings, and cakes for two weeks, while the other half (the control group) were given a standard diet.
The rats who consumed the cafeteria diet showed “impaired sensory-specific satiety” that continued up to a week after the cafeteria diet was withdrawn. The conclusion, according to scientists at the University of New South Wales, is that these junk food diets may alter the brain circuitry related to motivation and behavioral control.
Said another way, junk food is addictive and may kill your appetite for anything else.
"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 lead researcher Margaret Morris in a statement. "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."
Obesity is already a huge health concern in the United States, and the problem is quickly spreading to the rest of the world. According to the World Health Orgnization, global obesity rates have nearly doubled since 1980.
Adding to the apparent vicious cycle of overconsumption, junk food may also make you lazy. A similar study published earlier this year by researchers at UCLA found obese rats who were fed processed junk food were significantly less motivated to work for a reward—even when that reward was more junk food!
If these conclusions carry over to human beings, it might prove that losing weight is a lot more psychological than previously thought.