  The consequences of the non-Drude charge response in the normal state of
cuprates and the effect of the layered structure on electron-energy loss
spectra are investigated, both for experiments in the transmission and the
reflection mode. It is shown that in the intermediate doping regime the plasmon
resonance has to be nearly critically damped as a result of the anomalous
frequency dependence of the relaxation rate. This also implies an unusual
low-energy dependence of the loss function. Both facts are consistent with
experiments in cuprates. Our study based on the t-J model shows good agreement
with measured plasmon frequencies.
