I lost just a bit of weight (17 lbs.) and it took me about 1 1/2 years to do it. I know most people don't want to lose weight that sloooowly but it seemed to work in my case. I also took up strength training recently to tone and firm what's left after the diet.
I think my metabolism remained at a pretty steady state throughout because the loss took so long. And I exercise every day, both for work (I'm a commercial dogwalker) and for myself (yoga and weights). I think that keeps my metabolism up too.
I'm finding maintenance to be relatively easy because I've changed my eating habits. Glory said it all in her post in this thread. That's how I eat too. I do calorie cycle now and then just to keep my body guessing. I'm also starting to do new exercise things for the same reason. I'm going out jogging tomorrow "just for fun" and to see if my body will still do it.
I think experimentation is key in keeping both metabolic rate up and in keeping the brain from getting bored and overwhelmed with the idea that this is for life. That is not addressed in the book at all.
Living life simply and slowly is my goal now