Dense star clusters expand until their sizes are limited by the tidal field of their host galaxy .
During this expansion phase the member stars evolve and lose mass .
We show that for clusters with short initial relaxation time scales ( \lesssim 100 Myr ) the dynamical expansion is largely powered by mass loss from stars in the core , but happens on a relaxation time scale .
That is , the energy release following stellar mass loss is in balance with the amount of energy that is transported outward by two-body relaxation .