I have lots of food sensitivities, and I'm currently trying to be disciplined about sticking to an elimination diet too. I keep finding foods that I don't do well with, which has been great to get past the major issues (inflammation being the main one for me.) So far potatoes and tomatoes have been very inflammatory for me. I already don't eat gluten.
However, I'm going to change and now test some foods that I think will probably be safe for me, as I've been eating a very small group of foods, and I'd like to enlarge it a bit. Then the next time I find a trigger food, I can hopefully return to a much larger group of foods than I have been able to do for the past few months.
Lola, I don't have IBS, but rice seems to work really well for me, while potatoes and apples cause lots of bloating, and potatoes also create lots of inflammation as mentioned above.
Everybody is different. I too wish that I could come up with a unifying theme like Burgess has, but he's been working on this for years to figure out all that he has so far. And if I just assume that all nightshades are a problem just because tomatoes and potatoes are, I might miss out on some yummy red peppers when I don't need to, lol.
So for now I'm trying to test one food at a time. As Burgess wrote in his blog, it's a waste of time to test more than one food at a time. I know this from personal experience, because each time I add in a large group of foods, something always seems to start causing problems, and then I don't know what it is and I'm back to where I started.