The Relation of Fasting Ketosis in the Rat to the Preceding Diet and the Liver Fat

When rats are fasted they develop a ketonemia (ketosis) and frequently it is high enough to produce a measurable ketonuria. The height of the ket.osis is determined by many factors. When the diet is low in choline and in protein, the liver becomes very fatty (1) and the ketonuria on subsequent fasting is much higher (2,3) than it is in animals that have been on the stock diet or other food mixtures with a higher protein content. It seemed reasonable to assume that. the high degree of ketosis during fasting after a low protein intake was incident to the fatty liver. This appeared probable, for ketone bodies arise from the oxidation of fatty acids in the liver, and, during fasting after ordinary diets, fat generally accumulat,es in the liver during the period in which the ketosis is reaching its ultimate level. However, we have been unable to obtain a good correlation between the degree of ketosis and the amount of fat in the liver and have therefore been led to examine some of the dietary factors which determine the extent of the fasting ketosis.