A certain amount of glycogen is stored in the liver. It serves as an energy reserve until it's needed by the body. To a lesser degree, glycogen is stored in muscles. It is an important fuel source for the muscles, especially during exercise. In general, we can think of carbohydrates as either simple or complex.
Simple carbohydrates refer to a single sugar molecule or two sugars linked together.
Complex carbohydrates are long chains of sugars linked together. The rise in childhood obesity is associated with an increased sugar intake. Complex carbohydrates are the basis of a healthy balanced diet . The food guide pyramid recommends 6 to 11 servings of complex carbohydrates every day. However, AHA warns that a diet high in carbohydrates can cause changes in blood cholesterol levels.