Brown adipose tissue thermogenesis and energy metabolism

Obesity and diabetes have become a major epidemic problem. Preventing obesity has proven a challenge because this would require increased physical activity and/or reduced energy intake; both of which are difficult to enforce. Brown adipose tissue (BAT) is a major metabolic organ that contributes to the regulation of energy metabolism in small rodents. In humans, since its rediscovery in 2009, BAT has emerged as a potential target to fight obesity and related metabolic diseases such as type 2 diabetes. The BAT of humans is activated by acute cold exposure and mediates cold-induced thermogenesis. The metabolic activity of BAT demonstrates huge individual variation and is negatively associated with body fat accumulation and glucose intolerance. The decreased BAT can be reactivated and recruited by repeated cold exposure, which has the effects of increasing thermogenesis and decreasing body fat. Such effects of cold exposure can be mimicked by oral ingestion of some food ingredients with agonistic activity at temperature-sensitive transient receptor potential channels. To develop strategies to boost BAT thermogenesis for obesity prevention, more insight is needed into the physiological significance of human BAT and mechanisms by which BAT function is regulated by aging, as well as endogenous and environmental factors. This review will summarize the current knowledge on the activation of human BAT thermogenesis and its roles in obesity-related disorders.