excess energy from carbohydrates, proteins, and simple sugars is stored in cells around the body for a reserve, or later use. when your caloric intake is much higher than yourenergy usage through the day, your stored energy will remain stored. after a while the cells enlarge with an abundance or stored energy and you become larger. fat cells are just enlarged cell basically. everyone has a small amount of fat for cushion like your butt. depending on many health factors and genetics energy is processed at a specific speed aka metabolic rate