raspberry ketones extract is a chemical from red raspberries, as well as kiwifruit, peaches, grapes, apples, other berries, vegetables such as rhubarb, and the bark of yew, maple, and pine trees. Raspberry ketone is a chemical from red raspberries that is thought to help for weight loss. Some research in animals or in test tubes shows that raspberry ketone might increase some measures of metabolism. It might also affect a hormone in the body called adiponectin.