Healthy living * Weight loss

Junk food can be as addictive as drugs

Triggers similar reaction in the brain

Binge eating junk food and drug addiction triggers the same type of response in the brain, researchers have found.

Scientists from the Scripps Research Institute in Florida found that rats fed on a high calorie, high fat diet soon develop compulsive overeating habits, leading them to become obese.

Overeating and obesity in rats coincided with a chemical imbalance in the pleasure centre of the brain - the part associated with pleasurable experiences such as eating, sex and drug highs.

The scientists discovered that the pleasure centres in rats fed high fat foods - sausages, bacon and cheesecake - become less and less responsive through time, requiring the rats to eat more of the same high-calorie, high-fat foods until they became obese.

Even the threat of an electric shock couldn't deter the rats from eating the high calorie food.

The very same changes occur in the brains of rats that over-consume cocaine or heroin, and are thought to play an important role in the development of compulsive drug use, the scientists said.

Dr Paul Kenny, who co-led the research, said the study, which took nearly three years to complete, confirms the "addictive" properties of junk food.

"The body adapts remarkably well to change - and that's the problem," said Dr Kenny. "When the animal overstimulates its brain pleasure centres with highly palatable food, the systems adapt by decreasing their activity.

"However, now the animal requires constant stimulation from palatable food to avoid entering a persistent state of negative reward".

The scientists also found that the brains of rats fed on junk food had reduced levels of dopamine D2 receptors compared with rats fed a healthy diet. The receptor responds to a chemical - dopamine - which is released by the brain in response to pleasurable stimuli.

"These findings confirm what we and many others have suspected," Dr Kenny said, "that overconsumption of highly pleasurable food triggers addiction-like neuroadaptive responses in brain reward circuitries, driving the development of compulsive eating.

"Common mechanisms may therefore underlie obesity and drug addiction."

This article was published on Mon 29 March 2010

Image © Tomasz Trojanowski -

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