The Atikin's diet is one of the most misunderstood. Even he does not think people should stay on the two week instroduction longer than two weeks.
If you are an O blood type (or at least not an A type) the diet will work great for you. Make sure that you take some fiber. Ground flax seeds work great.
If I had to lose weight, here's what I would do. If you want to lose it fast (you have a special event coming up soon) I would do the Atkins diet for a couple of weeks, then migrate to the Blood Type Diet .
If you are not in a hurry and want a diet you can do for the rest of your life, just start off with the Blood Type Diet .
good luck whatever you decide.