It depends on what you mean by "work". Nothing will make your body shed excess weight like magic and that's true no matter what the ads say. But green coffee beans used to brew coffee or simply chewed as a snack can help rev up your metabolism much the same way drinking brewed black coffee will. It's the caffeine content that does this and you will get approx as much in green beans as you do commercially packaged and processed or flavored ones. If you want more caffeine simply adjust your brewing time upward and/or use a scoop or more additional coffee in your pot.
Get exercise daily that you like, eat a healthy diet and don't snack on anything unless it's a lean protein such as yogurt. Good luck.