If there is not enough carbohydrate available in cells to allow the acetyl-CoA to enter the citric acid cycle, it will be used to make ketones. Acetyl-CoA is a molecule that is important in some biochemical reactions involving protein lipid and carbohydrate metabolism. It function to transport an acetyl group to the citric acid cycle or the Krebs cycle for it to be oxidized for the production of energy. Ketone can be produced and is regulated from the acetyl-CoA. The rate of the production of this substance would increase during starvation or in other words there is less carbohydrates that is available in the body.