The raw, green coffee bean may contain a natural weight loss substance that disappears when roasted.

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offee may be the lifeblood that keeps most workplaces humming, but new evidence suggests that the drink's unroasted beans might also hold the key to cheap and effective weight loss. In a study presented to the American Chemical Society in San Diego this week, scientists said that a supplement extracted from green coffee beans helped patients drop significant poundage. Here's what you should know about the findings:

How was the research carried out?
This small preliminary study looked at 16 overweight young adults in India. Over 22 weeks, the participants were given, in turns, a low dose of an extract made from unroasted coffee beans, a high dose of the same supplement, and a placebo, three times a day. Their diet throughout the study was unchanged, and they were physically active . Between trials, the participants were given a two-week break for their bodies to reset.

How effective were the coffee beans?
The results were "striking," says Melissa Healy at the Los Angeles Times. Though a few participants given the extract only lost 7 pounds, others lost as much as 26 pounds. On average, the subjects lost 17.5 pounds each, and reduced their body weight by 10.5 percent. Body fat also declined by 16 percent, even though the participants were eating an average of 2,400 calories, burning roughly 400.

Is it because of the caffeine? 
"We don't think it's because of the caffeine in it," says Joe Vinson, the University of Scranton chemist who led the study. The extract itself contained roughly the same amount of caffeine as a half cup of coffee. So what made the difference? It may be a natural substance called "chlorogenic acid," says Michelle Castillo at CBS News, which "goes away when coffee beans are roasted."  

Does the extract require FDA approval?
It doesn't. As a dietary supplement, green coffee extract is already available as a naturopathic medicine and antioxidant. 

Why is this such a big development?
Coffee beans are cheap, and with over 35 percent of Americans qualifying as obese, it may prove to be a powerful tool. At about $20 per month, "green coffee extract is much less expensive than any of the weight-loss medications available over the counter or by prescription," says Healy. But scientists are cautious, as the pilot study has not yet been subjected to peer review. "This is certainly a provocative study," New York University's Dr. Gerlard Weissmann, a physician and biochemist, tells the Los Angeles Times. He says the next step will be to ensure that the weight loss was not simply due to "malabsorption," which occurs when the gut is unable to absorb vitamins and minerals passing through the intestine. 

Sources: CBS News, Los Angeles Times, Web MD, New York Times