Disclosed herein are systems and methods that reduce, remove, shape, and/or sculpt sub-dermal fat layers by selectively heating fat tissue, or that reduce the appearance of cellulite, using low frequency RF energy applied through one or more skin contacting electrode carried on a handpiece. The handpiece is manipulated manually or automatically to continuously move the electrode(s) across the skin surface during RF delivery. A motion detector may be employed to determine the speed and/or direction of movement of the electrode, and operating parameters such as the amount of applied RF power may be modulated in response to feedback from the motion detector. One or more cooling modalities including thermoelectric cooling, and/or forced air cooling may be used to cool or minimize heating of the skin.