Brown adipose tissue: regulation of thermogenesis and implications for obesity.

The role of brown adipose tissue in the development and maintenance of obesity has been a recent focus of research efforts. Brown fat serves as a heat-producing tissue, via nonshivering and diet-induced thermogenesis, because of a unique mechanism that uncouples oxidative phosphorylation. The importance of these forms of thermogenesis to energy balance has been characterized in animal models of obesity; increased metabolic efficiency has been attributed to impaired heat production and compositional and functional alterations in brown fat. Although the possibility exists that human obesity may partly result from inadequate thermogenesis, evidence that the defect is related to brown fat is tenuous. Currently, the contribution of brown fat to metabolic rate in human beings has been estimated as minor. However, even if it is found that differences in brown fat cannot explain differences in corpulence, interest in the tissue will likely continue. Because of its ability to waste calories, the potential for manipulating body weight by stimulation of brown fat remains a promising field of investigation.