  We discuss the accuracy of the usual procedure for neutrino energy
reconstruction which is based on the quasielastic kinematics. Our results are
described in terms of a probability distribution for a real neutrino energy
value. Several factors are responsible of the deviations from the reconstructed
value. The main one is the multinucleon component of the neutrino interaction
which in the case of Cherenkov detectors enters as a quasielastic cross
section, increasing the mean neutrino energy which can differ appreciably from
the reconstructed value. As an application we derive, for excess electron
events attributed to the conversion of muon neutrinos, the true neutrino energy
distribution based on the experimental one which is given in terms of the
reconstructed value. The result is a reshaping effect. For MiniBooNE the low
energy peak is suppressed and shifted at higher energies, which may influence
the interpretation in terms of oscillation. For T2K at the Super Kamiokande far
detector the reshaping translates into a narrowing of the energy distribution.
