A 2012 paper claiming a randomized, double-blind, placebo controlled crossover study demonstrated that green coffee bean extract helped people lose weight has been retracted. After the Dr. Oz Show touted this extract causes substantial weight and fat loss it became an international best seller. The U.S. Federal Trade Commission (FTC) states "the study was so hopelessly flawed that no reliable conclusions could be drawn from it."
PositiveTip: If it promises magical benefits, it is probably too good to be true!