I love my diet soda too! I usually don't get pouchitis from drinking it, but from eating too much sugar. That being said, I know that diet soda will increase my appetite which may cause me to eat too much in general; therefore increasing my output. It will also increase the gassy feeling in my pouch, which may or may-not be over the top. It probably isn't good for the inflammation in my pouch either. I know that when I drink it, that is the risk I'm willing to take. I consider it a treat and am trying to drink more water than soda