Coffee beans are naturally green, but they are usually roasted by the manufacturer before being sold to the consumer which turns them brown.
Coffee beans are naturally full of antioxidants and pharmacologically active compounds, two of the most important ones being Caffeine and Chlorogenic Acid.
Most of the chlorogenic acid is removed when coffee is roasted. This means that regular coffee beans won’t have the same effect even though there are plenty of other good reasons to drink normal coffee.
Chlorogenic Acid is believed to be the main active ingredient in green coffee beans. This ingredient can reduce body weight, reduce fat absorbed from the diet, reduce fat stored in the liver and improve the function of the fat burning hormone adiponectin. Caffiene, the other main ingredient, has also been shown to boost the metabolism.