After cellular glucose supplies are depleted, the body turns to glycogen as a short-term energy source.

Here's why:

* Glycogen is a stored form of glucose found primarily in the liver and muscles. When glucose levels drop, the body breaks down glycogen into glucose through a process called glycogenolysis. This provides a quick burst of energy.

Note: Glycogen stores are limited and can only sustain the body for a short period, typically a few hours. Once glycogen is depleted, the body will need to rely on other energy sources, such as fat and protein.