Actually, Dr. D. does say in the book that type Os do better if they are near ketosis (I would know what page that was on, but after buying four books, I still don't have one since my friends and family keep "borrowing" them). To induce ketosis, you have to reduce your carbohydrates to a very low level.

I was cranky when I started this diet because I didn't want to give up dairy products. So I didn't. At least not at first. I avoided everything else on the avoid list and stuck to the beneficial list except for two glasses of milk a day. I didn't even eat many neutral foods at first. As time went on, I found that my body gave me reason to give up the dairy products and now my beneficial-to-avoid ratio is about 90%. (Actually, giving up the wheat and the corn was the most amazing thing that has ever happened to me in the realm of my health.)

I'm telling you this because you seem to want to go on this diet for some particular reason, otherwise you would go your merry vegetarian way. My advice, which is totally amateur, is first to switch to a diet of highly beneficial vegetables, then, after you are feeling better, start adding the animal protein. You won't be sorry.

P.S. You just can't use logic on this diet regarding what hunter-gatherers might have done. Dr. D. has done some very specific research with lectins and blood based on observations made by him and his father. What a lovely gift it has turned out to be!