Here's why:

* Glycogen is a complex carbohydrate that is stored in the liver and muscles.

* It is readily broken down into glucose, which is the body's primary source of energy.

* This process is much faster than breaking down fats or proteins for energy.

* Glycogen stores are limited and are typically depleted within a few hours of strenuous activity or fasting.

Let me know if you have any other questions about how our bodies store and use energy!