  The observed mass-to-light (M/L) ratios of globular clusters (GCs) are on
average ~20% lower than expected from Simple Stellar Population (SSP) models,
which only account for the effects of stellar evolution. We study the M/L ratio
evolution of a sample of 24 Galactic GCs using parameterised cluster models.
The dynamical evolution of GCs is included by accounting for their dissolution
and by using a detailed description of the evolution of the stellar mass
function. The ejection of low-mass stars leads to a decrease of M/L, which is
found to explain the discrepancy between the observations and SSP models.
