The first question is if it is food not being absorbed or fluid actively going out. There can be intolerance to a lot of different foods including all dairy (lactose), other sugars, wheat protein (celiac disease) and probably many others. Not eating of course changes it. Not eating the wrong stuff and cutting everything out and adding one food back in at a time at 2-3 day intervals would sort this out. Rice is not commonly a cause and rice with a protein for a start would rule out food intolerance, which it probably is NOT. Then, irritation of the gut. Gall bladder disease is sort of this. I have an odd irritation of the gut since I choose to take a small amount of a medicine to which I am allergic. Rice and meat are not common allergens. Medicines that cause hives externally or have caused rashes will cause allergic responses which do include diarrhea. This is rare unless you are trying to do it. Gut infection is quite common and some of the infections (HIV, parasites, hepatitis) are very long lasting.