Gluconeogenesis is the production of new glucose in the body from non-sugar sources, mainly proteins. It occurs mainly in the liver and kidneys. It is, according to Dr. Greco, the major body energy source for cats, who lack the glucokinasethat let other animals synthesize glucose more rapidly after eating. Cats use another enzyme called hexokinase, which is not very efficient, for processing carbohydrates.. Gluconeogenesis happens slowly and steadily, in each cell of the body. An unrelated process, glycogenolysis, releases stored glucose very fast by breaking down glycogen in the liver.