Control of fat metabolism is very important for maintenance of energy metabolism in the brain as well as in the rest of the body. Much additional attention has been directed to the contributions of the central and autonomic nervous systems to homeostatic controls of blood glucose. Blood glucose is the immediate source of brain energy. Thus, maintenance of its homeostasis is essential in coping with the urgent need of energy supply to the brain. Our body is endowed with three means of maintaining homeostasis of the level of blood glucose: glycogen storage, food intake, and gluconeogenesis. In the 1940s several lines of evidence were presented that in rats, cats, and rabbits the hypothalamus was responsible for the control of food intake. It has been established that brown adipose tissues are involved in thermogenesis, in a cold environment, and after food intake.