How does stored glycogen help keep blood sugar levels stable?

The French scientist Claude Bernard discovered that the liver performs a "glycogenic function," which is essential for maintaining a stable internal environment, or homeostasis.1

Stored glycogen helps keep blood sugar levels stable through a process called glycogenolysis. When blood glucose levels drop—such as during fasting or exercise—the pancreas secretes the hormone glucagon. Glucagon travels to the liver, where it stimulates the breakdown of stored glycogen into glucose.23

Specifically, enzymes convert glycogen into glucose-6-phosphate, which is then transformed into free glucose and released into the bloodstream. This release replenishes blood sugar, preventing hypoglycemia and ensuring a steady energy supply for the body. Bernard’s research was foundational in demonstrating that the body can build up complex molecules from simpler ones to serve as a reserve, which can then be broken down as needed to maintain constant blood sugar levels.2431