Final answer:
Glycogenolysis is the process involved in regulating blood glucose levels during the postabsorptive state, which is the breakdown of glycogen into glucose to maintain blood sugar levels when dietary sources are not available.
Step-by-step explanation:
The mechanism involved in regulating blood glucose levels during the postabsorptive state is glycogenolysis. During this state, the body's energy needs are met by the breakdown of stored carbohydrates, such as glycogen, as dietary energy sources are no longer being supplied. Glycogenolysis is the process in which glycogen stored in the liver (and to a minor extent in the kidneys) is broken down into glucose, which is then released into the bloodstream to maintain blood glucose homeostasis. This process is crucial after periods without food (e.g., overnight), intense exercise, or any prolonged period with low carbohydrate intake. In contrast to glycogenolysis, other processes like glycolysis, which breaks down glucose for energy, and gluconeogenesis, the synthesis of glucose from non-carbohydrate precursors, serve different roles in glucose metabolism. Glycogenesis is the formation of glycogen from glucose, which is not a process used to increase blood glucose levels, but rather to store glucose.