Aside from offering an exotic and flavorful experience to the consumer, the "fully Indonesian" Bali Blue purportedly delivers a controversial benefit of unroasted green coffee beans: weight loss.

Green coffee is simply the unroasted seeds from coffee fruits. Typically, coffee bean sellers roast the seeds, a process that reduces levels of the chemical chlorogenic acid, which is believed o confer several benefits including weight loss.

Although several short-term studies suggest that chlorogenic acid slows absorption of fat from dietary intake, while also activating metabolization of fat, no scientific consensus supports the weight loss claim.

Green coffee as a weight loss supplement popularized more than a year ago by Dr.Mehmet Cengiz Oz, a cardiothoracic surgeon and daytime television host whose viewers readily consume and spread trends. The charismatic daytime doctor conducted his own short-term study of 100 women over two weeks, finding that those who took 400 milligrams of the extract lost two pounds on average.

In September, Dr. Oz declared green coffee, no matter the specific blend, to be a "fat burner that helps women lose weight."

Other purveyors of green coffee argue that extracts containing at least 50 percent chlorogenic acid slow the secretion of insulin in the body, helping to suppress appetite but also preventing the storage of fat.

The coffee klatch recently gained support from Katy Perry, whose appearance on this month's cover of Vogue features a noticeably slimmer actress. "I did a lot of my own prepping," Perry told reporters. "I kind of went on a cleanse; I did a lot of stuff like vitamins and supplements. I didn't drink alcohol for three months. I was really in the zone, I just wanted to be glowing for that cover."

She also took green coffee extract with chlorogenic acid.

In an analysis of several studies on green coffee extract, U.S. researchers found evidence in animal studies that green coffee may promote weight loss. "However, several caveats exist," they wrote. "The size of the effect is small, and the clinical relevance of this effect is uncertain."

The researchers concluded that more rigorous study should be conducted to assess the potential benefits of green coffee.

Below is a video from Dr. Oz puporting the weight loss benefits of green coffee:

Source: Onakpoya, Igho, Terry, Rohini, Ernst, Edzard. The Use Of Green Coffee Extract As A Weight Loss Supplement: A Systematic Review And Meta-Analysis Of Randomised Clinical Trials. Complimentary Medicine. 2010.