Which treatment works the best and fastest for steatorrhea?

Depends: Steatorrhea can have many causes. Pancreatic insufficiency, a condition where no enzymes to digest the food you eat are secreted by the pancreas, is treated with supplemental pancreatic enzymes that are taken with each meal. Other causes include celiac disease, crohn's disease, small intestinal bacterial overgrowth, short bowel syndrome. All of these conditions require different treatments.