Hi there Pukka8: I have IBS as part of my Fibromyalgia but I don't have a problem if I eat gluten free. Not celiac as far as the tests say, but VERY allergic (asthma, skin breakouts, and joint pain as well). There are a few things that are gluten free in IP packets but it's pretty limited and I also had to use some of my own vitamins as they could not guarantee some of theirs were Gfree.
Stay away from any IP packets that do not say gluten free - your coach should be able to access a list. I still lost all my weight using very limited kinds such as the Broccoli cheddar soup, Dark chocolate pudding, lemon poppyseed restricted bars, Peach Mango & Pina Colada drinks and that was about it for 4 months. I am at maintenance now and things are much easier - I don't use IP for my post "Funday" recovery day, I just use Vega protein powder for a smoothie or Garden of Life Raw Foods protein powder smoothie. No gluten and almost no carbs and seriously tasty with 15-20 grams of protein.
I would suggest that if you feel better going gluten free, go for it - who cares if you get a technical diagnosis. Your actual health is what counts!
You can message me if you need more info or you can also follow a thread for those with special dietary complications.