an ultrasound applicator, comprising:

at least one ultrasound transducer configured to generate unfocused ultrasonic waves in a frequency range of 1-7 MHz, and with intensity values selected from a range of 5-90 W/cm 2 and direct said unfocused ultrasonic waves to a selected tissue volume comprising fat tissue in a hypodermis tissue layer, wherein said at least one ultrasound transducer comprises a piezoelectric (PZT) plate configured to generate said unfocused ultrasonic waves and a coating disposed on said PZT plate, wherein said at least one ultrasound transducer contacts a skin surface indirectly via said coating, and wherein an overall thickness of said at least one ultrasound transducer is between 0.1 mm and 7 mm;

a control unit, comprising:

a control circuitry electrically connected to said at least one ultrasound transducer, wherein said control circuitry is configured to activate said at least one ultrasound transducer to generate said unfocused ultrasonic waves to selectively heat said selected tissue volume in said hypodermis tissue layer to a temperature of at least 52° C. for at least 2 seconds without causing damage to other tissue layers near the selected tissue volume.