Junk Food May be Addictive, Study Shows

Junk food alters the brain’s chemistry much like heroine or cocaine, according to a new study, meaning high-fat fare may be just as addictive.

Junk food can alter the brain in ways similar to heroin and cocaine, according to a new study published in Nature Neuroscience. Scientists say they have found compelling proof that high-fat foods have addictive qualities that can rewire the brain and drive compulsive eating.

In the study, when rats raised on regular food were suddenly given unrestricted access to a high-fat diet, they lost complete control over their eating. Within 40 days, their body weight had increased more than 25 percent.

The rats not only got fat, they also showed addiction-like changes in the reward circuits in the brain. Specifically, the obese rats showed lower levels of the dopamine D2 receptor, a biological chemical associated with feelings of reward. The brain releases bursts of dopamine as a result of pleasurable behavior, like sex and drug use, or when we eat food that tastes good. The more the body creates dopamine, the more we crave it, making the associated behavior habitual — often to the point of addiction.

In the new study, the more junk food the rats ate, the more they overloaded the brain’s reward circuits until they essentially crashed. As the pleasure centers in the brain became less responsive, the rats quickly turned into compulsive overeaters. They were motivated to keep eating to get their fix, much like drug addicts attempting to get high.

“They’re in a state of reward deficit, so that they’re now even more motivated to obtain rewarding food, perpetuating this vicious cycle even further,” study co-author Dr. Paul Kenny, an associate professor at Scripps Research Institute in Florida, told the Vancouver Sun.

When the researchers took the high-fat foods away, leaving only the healthy (but boring) meals – what the scientists referred to as the “salad bar option” – the rodents essentially went on a voluntarily hunger strike.

“They liked the junk food so much they would rather starve than shift onto the regular chow,” said Dr. Kenny, who co-authored of the new study. He noted that even after two weeks of having no junk food, “they still hadn’t returned to the level of intake that you see in the control animals for the standard chow. That goes to show just how powerful this food was.”

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