Lipolysis occurs virtually in all cell types and tissues. However, it is most predominant in brown and white adipose (fat) tissue. Lipolysis occurs within the cytosol or lysosomes of cells and is regulated via 3-enzyme cascade: ATGL-HSL-MGL. First, the ATGL and HSL enzymes hydrolyze triacylglycerol into a diacylglycerol, releasing a free fatty acid into the bloodstream. MGL catalyzes the hydrolysis monoacylglycerols to their correlated fatty acids. The glycerol generated by lipolysis functions as a source of carbon for gluconeogenesis in the liver, as fats in the body essentially function as stored energy for later use.