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It's being heralded as a revolutionary new weight-loss product that can melt pounds without the need for diet or exercise.

Although it clearly sounds too good to be true, green coffee bean extract is flying off shelves at natural food stores and is in high demand online.

"It's among the top sellers right now," said Stacey-Anne Bistak, who works at Noah's Natural Foods in Toronto. "We've had a steady run on it."

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It's no coincidence green coffee bean extract surged in popularity after being mentioned on The Dr. Oz Show. In September, after being taken to task by critics for calling green coffee bean extract a "miracle" product, Dr. Mehmet Oz conducted his own experiment on the supplement. Using 100 female volunteers, Oz said he found women who took the extract lost an average of two pounds in two weeks. Women who took a placebo lost an average of one pound during those two weeks.

Convinced? You just might want to reserve judgment.

What is it?

Green coffee beans are simply beans that haven't been roasted. Green coffee beans contain chlorogenic acid, which proponents say slows the release of glucose into the body after a meal, thereby promoting weight loss. When coffee beans are roasted, most of the chlorogenic acid is lost. The extract, made with chlorogenic acid, is converted into a capsule form before being sold to consumers. And it doesn't come cheap. A month's supply can cost between $20 and $30.

The claims

Just type "green coffee bean extract" into an Internet search and you'll be inundated with companies advertising its ability to help you lose weight. Look a little closer and you'll see that many of those sites reference one particular study to back up their claims. That study, published in the journal Diabetes, Metabolic Syndrome and Obesity, was conducted on eight men and eight women. They were each given a high dose and a low dose of green coffee bean extract, as well as a placebo, in three separate six-week-long experiments. Participants were encouraged to consume a similar number of calories each day during the course of the experiment.

After 22 weeks, or about five months, the researchers found that, on average, participants lost more than 17 pounds.

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"It has a significant weight loss" associated with it, according to Dr. Joe Vinson, a professor of chemistry at the University of Scranton in Pennsylvania and lead author of the study.

The catch

Although the study is widely cited as proof green coffee bean extract works, nutrition and obesity experts are concerned over the validity of the results. They highlight several problems with the study, notably the fact it has an odd, unconventional design and that it involved very few people.

They also point out that study participants lost weight during the placebo phase of the trial, which suggests green coffee bean extract was not responsible for their weight loss. For instance, participants may have felt encouraged to slim down because their weight and diet were monitored as part of the study.

"Clearly there's nothing magical about it," said Dr. Arya Sharma, a professor of medicine and chair of obesity research and management at the University of Alberta.

But even if you still want to believe the study results, consider that it says people can lose a significant amount of weight without altering their caloric intake or physical activity levels. It's impossible.

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"Usually when studies break the physical laws of the universe, there's usually something wrong with the study itself," said Dr. Yoni Freedhoff, medical director of Ottawa's Bariatric Medical Institute, who writes Weighty Matters, a popular blog on nutrition issues.

Under "Footnotes" in the study, the authors note that they have "no conflicts of interest in this work." That doesn't tell the entire story. Although Vinson is listed as the lead author of the study, he actually didn't do any of the research. The study was conducted in India. Vinson examined the data and wrote the study paper.

While Vinson notes that the green coffee bean extract used in the study was supplied by Applied Food Sciences Inc., a company based in Texas, he didn't mention that the company also paid him to write the study.

When asked about this potential conflict of interest, Vinson said that he doesn't gain financially if the company sells a lot of product and that the journal didn't require him to disclose the relationship.

But the lack of disclosure is serious because it could be misleading to those who read it, Sharma said.

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