Recent measurements of the Fermi surface with de Haas-van Alphen oscillations in LaFePO showed a shrinking of the Fermi pockets with respect to first-principle calculations, suggesting an energy shift of the hole and electrons bands with respect to local-density approximations. We show that this shift is a natural consequence of the strong particle-hole asymmetry of electronic bands in pnictides, and that it provides an indirect experimental evidence of a dominant interband scattering in these systems.