The study participants lost slightly more weight with the higher dose compared to the lower dose, but not a significant amount with the placebo, Vinson says. So, we have already found out how the green coffee extract works and how it aids in weight loss. Helping You Get Fit And Healthy Fast! On his program, the doc revealed the results of his own investigation, which involved recruiting women who either received a placebo or a mg green coffee bean supplement. RELATED: If you want to slimd down in a hurry, try one of these expert-approved quick weight-loss strategies.