Monday, April 26, 2010


Why you can’t eat just one

In a recent study published in Nature Neuroscience, researchers found that junk food can be as addictive as cocaine or heroin.

As part of a 40-day experiment, one group of rats were fed a nutritionally balanced diet while another group of rats were given a diet consisting of bacon, sausage, cheesecake, pound cake, frosting and chocolate.

As would be expected, this group of rats eating junk food gained more weight. They also became less active than the other rats.

In addition, they would eat this food even if given a mild electric shock, and refused to eat when their diet was replaced with a nutritionally balanced diet.

The researchers attributed this behavior to the release of dopamine by the brain, which occurs naturally in varying amounts, giving us the feeling of satisfaction or pleasure as a response to different enjoyable experiences, such as eating desserts.

Dopamine is the same chemical that is released in large amounts in cocaine and heroin addicts.

When dopamine is released in excess amounts, an alteration in brain chemistry occurs such that more stimulus is needed to produce the same results. Thus, the compulsive eating of junk food in order to obtain the same pleasure.

While, experiments in rats may not be directly applicable to humans, it may help explain a contributing factor to human obesity.

Junk food is addicting and can lead to weight gain and a sedentary lifestyle. This may be why you “can’t eat just one.”

Dr. Paul H. Deutsch is board-certified in Internal Medicine, a member of The William W. Backus Hospital Medical Staff and in private practice in Norwich. This column should not replace advice or instruction from your physician. E-mail Dr. Deutsch or any of the Healthy Living columnists at To comment on this or other Healthy Living columns, click below or go to the Healthy Living blog at

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