No molasses, no sugar. Some can manage with grazing on poor low quality grass some can't check out sugar/starch content in all foods as some are very high in sugar starch which you want to avoid. Some horses only get it once and changing feed and management can keep it at bay. Depending on his age, test for cushings. Feed hay try to get some which isn't rich - they are usually better on old grass if you let it grow up 2ft or more as it loses its richness.