Carbohydrates are stored in the muscles and liver in the form of glycogen, according to Iowa State University's sports nutrition program. Once the glycogen stores in the muscles and liver are full, carbohydrates are then stored as fat.
When a person eats a food that contains carbohydrates, the body breaks down the carbohydrates into smaller, simpler sugars, such as fructose and galactose. These smaller units of sugar travel via the bloodstream to the liver, and the liver converts the sugars to glucose. The glucose is then transported to the brain, tissues and muscles to be used as energy. If the body does not need energy, the glucose is stored in the liver and muscles for later use.