Glycogen is stored in the liver and the skeletal muscles. The stored glycogen is used by the body as an energy source, when more glucose is required than is available in the blood stream. The body can only store around 2,000 calories of glycogen.
If the glycogen storage reaches its maximum, then glucose becomes retained as fat. Stored glycogen functions as an energy reservoir when there is glucose deficiency, due to intense physical exercise or low intake of carbohydrates. These energy reservoirs are beneficial to athletes or those who exercise regularly. Hence, athletes should consume more carbohydrates regularly to restore glycogen.