This is a considerable chunk, and in some ways, it makes sense. The body prefers to use carbs for energy as they are the easiest source of energy to digest and can be converted into glucose with little and in some cases no effort. Glucose, also referred to as blood sugar, floats around in the bloodstream and is pulled in by cells that need energy. Having too much glucose in the bloodstream can be a very bad thing, however. To prevent this the body secretes a hormone called insulin which triggers the body to pull some of the sugar out of the blood and store it for later use, as fat.