The carbohydrates in fruits, grains, and vegetables are converted by the body into a substance called glycogen and used for energy. Some of this glycogen is stored in the liver. Some is sent to the muscles and stored as muscle glycogen, if those stores have been reduced through exercise or fasting, typically at night while sleeping (and thus a breakfast should be rich in carbohydrates to restore muscle glycogen for an energetic start to the day). And some of the carbohydrates become glucose (sugar) and remain in the bloodstream to be used by the brain, the kidneys, and the red blood cells, which all depend on blood glucose to function. Once the liver, blood, and muscle energy stores are filled, any extra carbohydrates are converted to fat -- for storage around such locations as the thighs and midsection, in the form, of course, of fat.
