A system is provided for reducing lipid content of adipocytes in a body. The system includes an optical device configured to illuminate a region of the body at a selective peak wavelength and at a selective power density for a selective time period. The system also includes a controller connected to the optical device to determine the selective wavelength, the selective power density and the selective time period to stimulate lipolysis in the adipocytes. A system is also provided for reducing pain in the body. A method is also provided for reducing lipid content of adipocytes in the body.