  We study the electron-energy loss spectra of strongly correlated electronic
systems doped away from half-filling using dynamical mean-field theory
($d=\infty$). The formalism can be used to study the loss spectra in the
optical (${\bf q=0}$) limit, where it is simply related to the optical
response, and hence can be computed in an approximation-free way in $d=\infty$.
We apply the general formalism to the one-band Hubbard model off $n=1$, with
inclusion of site-diagonal randomness to simulate effects of doping. The
interplay between the coherence induced plasmon feature and the
incoherence-induced high energy continuum is explained in terms of the
evolution in the local spectral density upon hole doping. Inclusion of static
disorder is shown to result in qualitative changes in the low-energy features,
in particular, to the overdamping of the plasmon feature, resulting in a
completely incoherent response. The calculated EELS lineshapes are compared to
experimentally observed EELS spectra for the normal state of the high-$T_{c}$
materials near optimal doping and good qualitative agreement is found.
