driving high-side N-channel MOSFETs in H-Bridge
I pressume that by power loss, you refering to the power dissipation on the transistors.

So in this case, P-channel MOSFETs have high on-resistence, so its common for high current
applications to use N-channel at the top of the bridge too.

To drive the top transistors, you have some options. Some of then:


Pulse-transformers
Gate-drive IC's that can be of different topology's like boot-strapping.
Isolated power supply with level-shifter
Isolated power supply with Opto-isolators


All with their characteristics.

Some good app-note
http://www.ti.com/lit/ml/slup169/slup169.pdf