Background: Brown adipose tissue (BAT) is recognized as the major site of sympathetically activated nonshivering thermogenesis during cold exposure and after spontaneous hyperphagia, thereby controling whole-body energy expenditure and body fat. Energy expenditure (EE) consists of basal metabolic rate (BMR), physical exercise and thermogenesis. Generally, BMR represents 65% to 75% of total energy expenditure which is determined by fat-free mass. In minimal activity it represents two thirds of total daily EE, in maximum activity it represents half of total daily EE RMR is controlled by the hypothalamus through neuroendocrine systems. As for thermogenesis, the brain, mainly the hypothalamus and the brain stem are responsible for the control of BAT thermogenesis through sympathetic projections.