I went on GAPS for myself from January 2012 to July 2012. Online people were saying they used GAPS to heal all sorts of problems (not just autism). So I tried it.
I lost about 30 pounds in those 5 months. 20 pounds in the first month.
I would often only poop once or twice per week before I started GAPS. My second week on GAPS I pooped something like 20 times in 5 days (7 poops on my poopiest day). And half of those were big poops! My pant size went from 36" waist down to 32" (and now I can even wear 30" size pants!).
I felt very fatigued all the time before GAPS. Now I feel a lot less fatigue (I still have some on occasion). I was experiencing a gradually increasing social anxiety before GAPS. Now I have no problem looking the guy behind the counter in the eye to ask if he has snapper or rockfish heads and carcasses.
I stopped after only 5 months because I lost power for 6 days and lost my whole supply of frozen broth (at least 2 months worth). I didn't have any other sources or supplies of good broth and I was missing/craving some non GAPS foods (like properly soaked organic oatmeal). I have rebuilt my supply and should go back on GAPS for more healing. I eat according to GAPS and Nourishing Traditions principles now, but I think I still have some gut dysbiosis to heal. I had a ruptured appendix many years ago and I don't think I've fully recovered (especially from all the anti-biotics I took). A strict GAPS diet would result (in my opinion) in greater/faster/better healing. I have a white coating (sometimes orange if I have just eaten a carrot) on my tongue that won't go away even with brushing/oil pulling/whatever. Chewing beeswax removes it for a few hours, but it always comes back.
I want to put my son (8 years old) on GAPS (he needs it!). I think he is on the autism spectrum, but nobody else seems to think so, even though he is receiving special services at school. His mom has him 60% of the time and stated that the diet was far too much work for her. Without her on board I don't think I can make it work. I have thought about making all his food and sending it over to her place. Maybe if I go on it for another 5 or 6 months I'll be that much healthier and capable and comfortable (and faster) with the food preparation and everything and I'll be able to make all of his food and send it over for him. But another problem is although she has him 60% of the time he isn't always with her and teachers at school give out candy (at least once per week), not to mention other kids who would give him candy or other stuff.
I love GAPS but haven't been able to convince anyone in my family to try it out. My older brother (who would really benefit) said that he would never go on my diet. I took my fish broth over to his place to eat it and he had the ugliest look on his face when I told him what it was. His face got even more twisted when I told him that going on the diet might even result in headaches, fatigue, pain, diarrhea, all things that I went through as part of multiple healing crises. In fact it is difficult for me to recommend GAPS because my healing crises were quite severe in duration and intensity, but I'm in a much better place physically now. The pain I was feeling was as if all the ill and injured parts of my body were all crying out at once to get the nutrition that I was supplying. So right under my appendectomy scar was extremely painful, my ankle where I had torn off the ligament (completely torn right off the bone) 20 years ago was extremely painful, multiple fingers and toes were in extreme pain (sometimes dull and achey and sometimes very acute - even for injuries that were 20 years old or older) and lot of other places too. It was like they were all saying, "I'm hurt, send nutrition and nourishment and resources and healing to me!" Like it was as if in the past my body had sealed up these injured places - as still injured - because I didn't have the resources to fix those areas, so my body just sort of sealed them off, but when I went on GAPS the resources were there to heal those sites and so my body opened those sites back up and that is when the floodgates of pain just opened up.
I love the GAPS diet, but the book left a lot to be desired. I felt like I was reading a foreign language when reading the book (Nancy Campbell-McBride writes in English - like from England English, not like from USA English). Often things were repeated but with slight variation, so I was unsure which repetition/variation I should follow. I had difficulty following the book in some parts (admittedly, that could be more of a problem with me than the book). But I love the results of following the diet.
My son's mom remarked that I better not end up weighing less than her (I weigh what I did my freshman year of college - that was 17 years ago). My brother said that my body could be used in advertisements (I took off my shirt to show him results after 5 months). My social anxiety is gone. My fatigue is extremely reduced. Old injuries are or seem to be healed/healing. I saw a friend (and his wife) a few months ago that I hadn't seen in 2 years. He was shocked at my transformation so I told him all about it. His wife said that I was smiling now, that I wasn't smiling 2 years ago (and that is true, I wasn't smiling two years ago) and that was before I got into all the details about GAPS.