The Letter is an expanded commentary to the paper 'Fullerene as an electron buffer: charge transfer in Li@C-60', by Pavanello and co-authors [8]. We calculated the electron density distribution in the space inside and outside the fullerene cage in Li@C-60 complexes differing in total charge, based on Gauss's law. It allowed us to determine the charges contained inside surfaces isomorphic with the fullerene cage and contracted or enlarged with respect to the latter. For every complex, a surface was found in the vicinity of the central Li atom such that the charge enclosed within it was equal to +1. (C) 2013 Elsevier B.V. All rights reserved.