They do switch your plans as you lose weight. The plan you are on is based on the number of pounds you have to lose plus your activity level and age factors in too. I wouldn't worry about the number of calories because the major concentration is eliminating sugars and balancing out the diet plan with proteins, starches, fruits, fats, dairies and vegetables. It almost reminds me of the old weight watcher plans based on exchanges. My doctor loved it, said it is a very sensible way to eat.
Just my 2 cents, but there are a lot of success stories here. The COD works with you if you hit plateaus, etc and there is a tremendous amount of information and support on this message board. Check out the newbie threads at the top, they go into program details, plan comparisons, etc.