I would recommend an elimination diet first. Most people wind up testing positive for 20+ foods on those tests -- including me. I tested positive for a lot of foods that did not bother me at all -- and I tested and re-tested by eliminating and re-introducing multiple times. Those tests usually result in overwhelming people because who can eliminate that many foods from their diet? So they do nothing.

Since I did it AFTER the elimination diet, it only helped me to zero in on some things that were more complex. For example, I thought chocolate upset my stomach, but I tested positive for vanilla, which is in most foods that have chocolate. I was able to find some chocolate bars that had no vanilla in them, and I could eat them just fine. Mind you this was a very minor complaint compared to the foods that caused me to go days without pooping. If your #1 complaint is constipation, the elimination diet will give you the info you need.