As he becomes progressively more starved, his liver will synthesize ketone bodies as an additional fuel for muscle, which cannot meet all of its energy needs from fatty acid metabolism. This spares glucose for the brain and red blood cells. Higher than normal quantities of ketone bodies present in the blood or urine constitute ketonemia (hyperketonemia) or ketonuria, respectively. The overall condition is called ketosis. The basic form of ketosis occurs in starvation and involves depletion of available carbohydrate coupled with mobilization of free fatty acids . 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