On supersonic aircraft such as the SR-71 and F-18, my understanding is that lift is generated by every square inch of the aircraft planform during supersonic flight, rather than just the wing area which is more the case during subsonic flight.
Since the Aerodynamic center moves from its 1/4 cord point back to the Centroid of the Area as you go supersonic, the fuselage area ahead of the wing helps reverse the increase in stability which would tend to increase stabilizer (stabilator) "trim" drag and create excessive nose heaviness.
So the SR-71 example is a lifting fuselage, but it is done for stability reasons which improves aircraft efficiency during supersonic flight.