Osmotic Diarrhea Dr. Travis Stork: So osmotic diarrhea simply is this, your body, your gut pulls water in much like a sponge. So something is in your gut that literally pulls water in and then this is what happens out the bottom. Dr. Jim Sears: And it sounds like that too. Dr. Travis Stork: You know the smell is a little bit better though. There’s another way you can actually get diarrhea believe it or not, laxative. A lot of laxatives are what cause that osmotic diarrhea.