Brown Adipose Tissue (BAT) which is composed of brown adipocytes is a major site of mammalian non-shivering thermogenesis and energy dissipation. Recruitable brownish adipocytes, termed “beige adipocytes” (also known as “brite adipocytes”), were discovered in White Adipose Tissue (WAT). Beige adipocytes are induced by sympathetic nerve activation after cold exposure or treatment with β3-adrenergic receptor agonists. Although the gene expression profile in beige adipocytes is different from that in brown adipocytes to some extent, both brown and beige adipocytes express the thermogenic genes such as mitochondrial uncoupling protein 1 (UCP1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc1α), and have high thermogenic ability. The modulation of thermogenesis in brown and beige adipocytes could be an important application for body weight control and obesity prevention.