I followed the type A diet pretty religiously for four years. Didn't do a thing for me that I could tell. Except I was running around feeling hungry most of the time because of the lowfat recommendation. I have to admit that I was a bit brainwashed and it took awhile to get the diet out of my mind and even now when I hear people tell me that they do well on this food or that food I often wonder what their blood type is but I know the diet is mostly bunk. And yes it works for O's. Most of the A's had problems.