The radiofrequency consists of the application of high-frequency electromagnetic waves on the skin that causes controlled heating of the different layers of the dermis, which favors: The formation of new collagen. Lymphatic drainage. Circulation of the skin and subcutaneous tissue. In the case of radiofrequency, ultrasound is used to eliminate that localized fat. It is normally used on the belly, thighs or buttocks. And several sessions are needed to eliminate the unwanted kilos and firm the skin.