Overeating? Blame Your Genes

Oct. 17 -- THURSDAY, Oct. 16 (HealthDay News) -- A gene could help prod people to overeat and gain excess weight, new research shows.

The finding probably won't provide a "magic bullet" for weight loss, but it does reinforce the value of good eating habits and exercise, especially for young people, scientists say.

The study, reported in the Oct. 17 issue of Science, is the latest in a series focusing on the brain's response to food using the neurotransmitter dopamine. Cells in the brain's "reward" centers release dopamine when people eat, causing that feeling of pleasure, researchers explain.

Previous studies have shown that some people have fewer brain cell receptors for dopamine, which leads them to eat more to gain the same pleasurable effect. The new study used scans of the brain pleasure centers of a group of women. They revealed a sluggish dopamine response in the brains of some of the women.

"This is the first imaging study which found less activation of dopamine receptors in [some] humans," said study lead author Eric Stice, a scientist at the Oregon Research Institute in Portland.

Women with one form of the D2 dopamine receptor gene had the lowest pleasure response when drinking a milkshake, the scans showed. They had to consume more of the shake to get the same pleasure response. Follow-up study found that these women were also more likely to gain weight over the following year.

The study was done in collaboration with researchers at Yale University and the University of Texas at Austin.

"What is new here is that for the first time they have identified the consequences of this genetic polymorphism [type] in how the brain functions," said Dr. Nora Volkow, who worked on earlier studies at Brookhaven National Laboratory that established the role of the D2 gene in overeating. She is now is director of the U.S. National Institute on Drug Abuse.

Volkow noted that prior studies had linked this form of the gene to obesity, and the new work "shows an association in the brain region that governs pleasure. The response is different with this polymorphism."