Junk food addiction

You knew those Ding Dongs, candy bars and strips of bacon weren't good for you. But now comes a study suggesting that junk food may be addictive in the same way as heroin or cocaine.

Researchers at Scripps Research Institute in Florida found that rats given unlimited access to the kind of high-fat, high-calorie food available in convenience stores - such as Ho Hos, candy bars and sausage - became compulsive overeaters as the pleasure pathways in their brains became less and less responsive, forcing them to consume more to get the same amount of pleasure. These rats also went for the junk food even when they had to endure a slight shock to their foot to get at the food. These behaviors, according to the researchers, are classic hallmarks of addiction.

"Not only did we find that the animals' brain reward circuits became less responsive at they continued to overeat and become obese," Paul Kenny, an associate professor of molecular therapeutics at Scripps, reported at the annual meeting of the Society for Neuroscience, "but that decrease in responsiveness was similar to what our laboratory has seen previously in rats as they become addicted to cocaine or heroin."

When, after 40 days of unrestricted access to the junk foods, the rats were then deprived of it and fed a more nutritious food pellet, the animals refused to eat, even though they were clearly starving.