Under conditions of bile salt or pancreatic enzyme deficiency, exogenous fats can reach the colon and be metabolized by bacteria, leading to fatty stools.

“most of the fatty acids that get to the colon are derived from fiber in other words they're not exogenous that's true normally but not always so for example under abnormal conditions in which bile salts or pancreatic enzymes are deficient then those fat can get into the colon one gets fatty stool bacteria can metabolize that”