We construct three extremely different scenarios of the star formation histories applicable to a sample of dwarf galaxies, based on either their present metallicity or their luminosity. The three possible scenarios imply different mechanical energy input rates, and these we compare with the theoretical lower limits established for the ejection of processed matter out of dwarf galaxies. The comparison strongly points to the existence of extended gaseous halos in these galaxies acting as the barrier that allows galaxies to retain their metals and enhance their abundance. At the same time, our findings strongly point to a continuous star-forming process, rather than to coeval bursts, as the main contributor to the overall metallicity in our galaxy sample.