Final answer:
Insulin is the key factor that controls the absorptive phase of metabolism.
Step-by-step explanation:
Insulin is the key factor that controls the absorptive phase of metabolism. When the body is in the absorptive state, insulin is released by the pancreas in response to increased blood glucose levels. Insulin promotes the uptake of glucose by liver cells, muscle cells, and fat cells, as well as the conversion of glucose to glycogen for storage.