If you eat more calories than the body uses, it will get kept as fat. The energy stores used is not your stored fat, but rather it’s protein and carbohydrates (carbs) that will provide many of the energy (saved fat makes up an extremely small percentage). When this occurs your body needs less energy to keep its brand-new lower body weight (keep in mind the body weight is lower due to the fact that you loss muscle), which is why your body conserves energy by slowing down the metabolism.