Fat vaccine works in rats

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(This article was #98 in Discover Magazine’s top 100 stories of 2006.)

In August, immunologist Kim Janda of the Scripps Research Institute grabbed headlines with reports of a vaccine against obesity. The vaccine triggers an immune response that targets ghrelin, a hormone naturally made in the gut and transported to the brain; ghrelin spikes with hunger and is thought to stimulate the storage of body fat.

In the study, rats that received the vaccine ate the same amount of food as the control group, but they gained less weight and had 20 percent less body fat. “I expected them to eat less, but it appears that what we saw was a result of metabolism,” Janda says. “Losing weight, losing fat—can’t ask for anything more than that!”

Now the reality check: The researchers followed the rats for only one week after the animals received their last booster shots. Long-term results could be very different. Michael Schwartz, professor of medicine at the University of Washington at Seattle, warns that the weight loss could prompt the body to compensate by making more of other weight-related hormones. Meanwhile, neuroscientist William Colmers of the University of Alberta worries about the wisdom of vaccinating the body against one of its own molecules. “It’s an intriguing idea, but it worries me considerably,” he says. “I sure as hell wouldn’t take it, no matter how fat I was.”

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