High mass stars, even when they are on the main
sequence, continuously lose small amounts of mass in a stellar
wind, similar to the solar wind. The wind particles
may be accreted onto the black hole.
Alternatively, a post-main sequence star, even of
relatively low mass, will expand as it rises on the giant
branch of the HR diagram to a size where it fills its
Roche lobe, spilling over onto the black hole.