Thanks for all the replies. So far I've been doing this for about 3 days. Yesterday I figured out how many calories my body had wanted, and it was about 1200.
I was really surprised by that, since when I count calories I can barely be OK with 1500 or so. I think maybe it's working for me because I do a lot of mindless/emotional eating, so having to think "Am I really hungry?" Makes me stop that. Next week's weigh in will be about 1 week of eating according to the book, so I'll know how much difference it made then.