Green coffee beans are simply coffee beans that are un-roasted. The roasting process of coffee beans reduces amounts of the chemical chlorogenic acid. Therefore, green coffee beans have a higher level of chlorogenic acid compared to regular, roasted coffee beans. 

Chlorogenic acid in green coffee is thought to have health benefits for weight management, heart disease and diabetes.

Green coffee became popular for weight loss after it was mentioned on the Dr. Oz show in 2012. The Dr. Oz show referred to it as “The green coffee bean that burns fat fast” and claims that no exercise or diet is needed.