The raspberry ketone extract that's present in red raspberries as well as other fruits. It's a favorite for those who are overweight but it's not known how it can help. It's thought that raspberry ketone may enhance metabolism, boost the rate at which your body burns fat and also reduce appetite. The evidence for humans isn't as strong. The ketone of raspberry is also present in peaches, kiwifruit apple, grapes and various other fruits, and rhubarb along with the bark of the yew pine, and maple trees.