Sorry that I am so embarrassingly late in replying to this thread but oh well.
I read the book and what annoyed me was how the author consistently glossed over the weight regain part. All that she mentioned was that suddenly all the weight was back and they just regained and so on (can't remember the exact wording) and she just left it at that. No word on how (or even IF) people tried to maintain their new weight, just stating that "oh well now the weight is back on again" because leaving it like that served her purpose. Sure, biology is incredibly important but so is behaviour and I refuse to believe that we are powerless automatons, completely enslaved by our biology. It's blatantly clear that Kolata did not want to go into maintenance, and how people actually do it, because that wouldn't make her glum conviction, about how it's impossible to keep weight off, as dead certain as she made it out to be.