Membrane fusion requires restructuring of lipid bilayers mediated by fusogenic membrane proteins. Peptides that correspond to natural transmembrane sequences or that have been designed to mimic them, such as low-complexity \"Leu-Val\" (LV) peptide sequences, can drive membrane fusion, presumably by disturbing the lipid bilayer structure. Here, we assess how peptides of different fusogenicity affect membrane structure using solid state NMR techniques. We find that the more fusogenic variants induce an unaligned lipid phase component and a large degree of phase separation as observed in (31)P 2D spectra. The data support the idea that fusogenic peptides accumulate PE in a non-bilayer phase which may be critical for the induction of fusion.