Brown adipose tissue (BAT) has recently been rediscovered in humans and burns fatty acids for the production of heat in order to defend the body against cold. We revealed an exciting new aspect of brown adipose tissue biology, deeply impacting the general concepts of lipid and lipoprotein metabolism. Using state-of-the-art nanotechnology we decipher the molecular mechanism how nutrients are delivered to BAT and how activation of BAT can be used to correct elevated blood lipids and how to combat obesity. Recently, by comparing gene expression signatures from human biopsies it was demonstrated that UCP1-positive “BAT” cells resembled those of murine “brite” adipocytes more closely than classical brown adipocytes. However, it remains unclear whether so called “brite” adipocytes arising also in white adipose tissue (WAT) of mice are as powerful as their brown adipocyte relatives. We were able to show that the conversion of white to brite adipocytes creates a cell type metabolically as powerful as classical brown adipocytes. This process is associated with a shift in the lipidomic landscape from dietary to endogenously produced fatty acids in WAT and also in plasma. Thus, the formation and activation of brite adipocytes in WAT initiates a metabolic reprogramming of glucose and lipid metabolism in WAT within days, ameliorating whole body metabolic health. *All experiments with mice as well as their sacrifice afterwards were conducted under anaesthesia (intraperitoneal injection of 90mg/kg xylazine and 1.28 mg/kg ketamine). All experiments All experiments were performed with approval from Animal Welfare Officers of the University Medical Center Hamburg-Eppendorf and Behörde für Soziales, Familie, Gesundheit und Verbraucherschutz Hamburg, Germany.