I mostly do the paleo diet and NSD. I didn't eat fruit except berries for like 6 weeks in the summer, but I did eat starch, and I did not improve as much as when I added in fruit but cut out starch. I was very strict for about 4 months on paleo and NSD, and I improved a lot. Once I got much better (I was also on medication) I started being less strict with my diet and symptoms started coming back. So then I got strict again, and improved again. It's really hard to stick to the diet. I've noticed that as long as I stay on the diet like 80 or 85 percent then if I cheat I don't really feel it unless I eat terribly for a few days in a row. I forget easily when I'm feeling well how bad it was and I quickly get back on the diet when I'm flaring up.
