Fruits and vegetables, including grapes, tend to be low in energy density, meaning they don't have many calories per gram. Eating mainly foods low in energy density can help you maintain a healthy weight because you can fill up on fewer calories than if you ate foods higher in energy density.ne way to include grapes as part of a healthy diet is to eat them in place of foods higher in energy density, such as cookies, cakes, ice cream and other sweet treats.