I think what happens is that the Cyclin component of the MPF is degraded. MPF or mitosis promoting factor, consists of two important cell cycle regulatory protein called the cyclin and cyclin dependent kinases (CDK). The cdk and the cyclins are the major control switches for the cell cycle, causing the cell to move from G1 to S or G2 to M.
Provision of energy. Fats are a source of energy in the human diet, together with carbohydrates and proteins, the other two main macronutrients.