Observation of the efficient second-harmonic generation (SHG) in silica fibers drew a lot of interest, as second-order processes in centrosymmetric materials should not occur. In this Letter, we extended a theoretical model of self-organized SHG to include an attenuation and investigated the influence of fiber loss on the self-organized SHG process. We performed calculations of energy conversion efficiency for SHG in microstructured optical fibers. Finally, we referred the simulation results to the measured SHG efficiency in a microstructured side-hole germanium-doped silica fiber. The extended model should be applied for the fibers with loss beyond 0.01 dB/m. Even in such fibers, efficient SHG without an external second-harmonic beam is possible.