The results of a recent laboratory study involving mice were published in the Frontiers in Psychology journal. Although experts have known for some time that a diet consisting of junk food causes fat gain, the study revealed it does more, which was surprising to most of the researchers. When junk food was fed to mice, their appetite for new foods, which typically drives them to find a balanced diet, decreased. This raised the question of what would happen if humans also followed a diet primarily of junk food.

Using the information taken from this study, researchers gained a better understanding of how consuming excessive junk food can alter behavior and reduce self-control. Of course, a diet of junk food also leads to overeating, which then prompts unhealthy weight gain that moves into obesity.

Led by Professor Margaret Morris, Head of Pharmacology from the School of Medical Services, UNSW Australia, along with her team of qualified researchers, were able to teach young male rats how to make an association between two flavors of sugar water to include grape and cherry with two unique sound cues. Rats lost interest in the flavor recently indulged in, thereby no longer responding to the sound cue.

In the wild, this is a natural reaction that prevents animals from overeating but also promotes good health. However, after being on a two-week diet whereby rats had access to foods like cookies, cakes, and pies that offered 150% more calories, their weight increased by 10% but even more interesting, there was significant change in behavior.

After this two week timeframe, the rats became uninterested to food choices but also, the sound that cued extremely familiar taste was avoided. To researchers, this was a strong indication that the rats’ natural preference for newness was gone. Even after a healthy diet was offered to the rats again, the effects of the junk food diet lingered for some time.

Taking everything into consideration, experts associated with this study think a diet consisting of junk food causes lasting changes within the reward regions of the brain. For instance, the area of the brain where decision-making occurs is called the orbitofrontal cortex. Because the brain’s reward circuitry is very similar in all mammals, from this study, it appears humans may have trouble limiting intake of certain foods.

As stated by Dr. Morris, identifying behavioral change in humans who consume large portions of junk food could change responses to signals linked with food rewards. She goes on to say that “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 coming by”.

The World Health Organization now estimates that more than 10% of adults in the world are obese. Of those, a minimum of 2.8 million people die directly related to complications of excess weight and/or obesity. While there are numerous health risks connected this problem, the most common include cardiovascular disease, diabetes, and even cancer.

The world’s obesity epidemic is not getting better, it is becoming worse. Not helping are all the food manufacturers who proudly advertise foods that pack on pounds such as chocolate. While more studies are needed, researchers may have discovered some key information that in the future, will help fight the global obesity epidemic.