Final answer:
In times of starvation, the excess acetyl CoA from β-oxidation leads to the formation of ketone bodies through ketogenesis to provide an alternative energy source.
Step-by-step explanation:
During starvation, the acetyl CoA coming from β-oxidation of fatty acids is not used fully by the Krebs cycle due to the excessive amounts of acetyl CoA generated. Instead, it leads to the production of ketone bodies through the process of ketogenesis. This adaptation occurs because glucose levels are low and the body needs alternative energy sources. Ketone bodies such as acetoacetate, β-hydroxybutyrate, and acetone are synthesized in the liver from the accumulated acetyl CoA. These serve as an alternative fuel source for various tissues of the body, including the brain, during prolonged periods without food.
However, some of the acetyl CoA is used to synthesize a group of compounds known as ketone bodies: acetoacetate, ß-hydroxybutyrate, and acetone. These ketone bodies can serve as a fuel source if glucose levels are too low in the body, such as during prolonged starvation or uncontrolled diabetes.