Ketone bodies are by products of metabolism of?
Carbohydrate
Protein
Fat
All of the above
Free fatty acids are the precursors of ketone bodies in the liver. While an active enzymatic mechanism produces acetoacetate from acetoacetyl-CoA in the liver, acetoacetate once formed cannot be reactivated directly except in the cytosol, where it is used in a much less active pathway as a precursor in cholesterol synthesis. This accounts for the net production of ketone bodies by the liver. Ref: Botham K.M., Mayes P.A. (2011). Chapter 22. Oxidation of Fatty Acids: Ketogenesis. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.