An apparatus for treatment of a subcutaneous fat region includes a source of electromagnetic radiation generating electromagnetic radiation having a non-fat selective wavelength. A delivery system is coupled to the source of electromagnetic radiation and is configured to deliver the electromagnetic radiation to the subcutaneous fat region for at least 300 seconds. A controller is configured to adjust an average power density based on a thickness of skin overlying the subcutaneous fat region, and to cause necrosis of at least one fat cell in the subcutaneous fat region. The non-fat selective wavelength is 950 nm to 1090 nm, 1100 nm to 1160 nm, 1,300 nm to 1625 nm, or 1,800 nm to 2,200 nm.
