I very much believe in the setpoint theory,although i wish it weren't true.
When I was 9 years old I weighed 200 lbs, about the same weight i weigh now. I have NOT been able to really get below this weigh -- ever. Even with the band ( I did get to 198 for 1 day over a year ago). I actually went to doctors about this, because i am restricted, I work out obsessively 6 days a week for 1-2 hours a day, but my weight doesn't budge.
The doctor told me that setpoint is true and that my body has it and that's why I can't lose more weight. I wish it wasn't true, I hope it isn't true, bc I think I "deserve" to see what life is like in the lower part of onderland.