A system 30 and method(s) 100 for thermal treatment of a selected target within a subject is disclosed. System 30 includes RF source 10, phase shifter 14, impedance matching network 11 and resonator 13. Applicator 3 conveys output signal 17 from energy source 10 through surface 6 of biological tissue 4 to predetermined energy dissipation zone 5 after output 17 has been processed by the phase shifter 14, IMN 11 and resonator 13. Stationary water molecules 1, such as those in fat cells, are heated. System 30 is operative to heat a volume of biological tissue beneath the biological tissue surface 6 such that surface 6 of biological tissue 4 is maintained at a lower temperature than predetermined energy dissipation zone 5 without a cooling device. The invention is useful in selective heating of cellulite bodies as a means of treating cellulite.