Yeah, I think the IBS diagnosis is way overused by lazy docs who just want the insurance code to bill a condition and don't take the time to do the necessary investigations. Anyway, celiac disease causes so many problems because it affects absorbtion of nutrients in the small intestine. In such people, gluten causes an immune system reaction that results in destruction the tiny villi in the small intestine that allows the body to absorb vitamins, etc. Any malabsorbtion problem can contribute to the oil slick in the toilet. Also, lots of people experience this following gallbladder surgery since bile is no longer being stored in the gallbladder and it flows unchecked to the intestines. I guess I'm taking the long way around to say fatty stools are just a symptom, and nothing to worry about by itself. It can occur if you simply eat a high-fat meal too.
Living in the Republic of Texas minus a gallbladder, appendix, uterus, and 18" of colon; but living with my wonderful husband, 2 dogs, 1 cockatiel, and 2 gold fish.