Biochemical mechanisms related to the homeostatic regulation of lipogenesis in animals

Since most animals are intermittent eaters, they are confronted with the problem of temporarily storing much of the chemical eriergy ingested as food. Fat takes up less volume and weighs less per calorie of stored chemical energy than either carbohydrate or protein. Thus, in animals whose major foodstuff is carbohydrate, the use of lipogenesis as the primary means by which the energy of dietary carbohydrate is stored affords maximum efficiency. The major honieostatic function of lipogenesis is to store as fat the chemical energy of carbohydrate ingested in excess of the immediate energy requirements of the organism. Clearly, a process as vital to caloric balance as fat synthesis must be precisely regulated to meet the everchanging energy needs of the organism. While the experimental data on the regulation of lipogenesis are vast, they present a far from complete picture. The purpose of this review is to analyze these data and, when possible, formulate some general concepts concerning the biochemical mechanisms involved in this homeostatic regulation. EFFECT OF FASTING ON LIPOGENESIS