Obesity is an important risk factor for many diseases, including cardiovascular diseases, metabolic syndrome and cancers. Excessive dietary intake of caloric food results in its accumulation in white adipose tissue (WAT), whereas energy expenditure by fat utilization and oxidation predominately occurs in brown adipose tissue (BAT). Reducing obesity has become an important prevention strategy of research interest, focusing in the recent years, mainly on browning of WAT, the process during which the enhance of the mitochondria biogenesis occurs and then white adipocytes are converted to metabolically active beige adipocytes. Sirtuin1 (SIRT1), the most known isoform of sirtuin deacetylases, is implied in the browning of WAT process. In fact, it is a sensitive sensor of cell energy metabolism and, together with other sirtuin isoforms, contributes to this differentiation process. This chapter provides an overview about SIRT1 involvement in browning of WAT as a target molecule that can thereby contrast obesity.