The amount of irrationality surrounding the obesity topic is really absurd. This following is a good example:

http://www.jhsph.edu/publichealthnews/press_releases/2008/wang_obesity_projections

The article claims that by 2030 86% of Americans will be overweight. This is based purely on extrapolating the trends of the last 30 years. My own reading of the actual literature on the topic implies that a large minority of people are simply not weight-gainers. They have a lower appetite or have faster metabolisms or something other factor that protects them from weight gain. My understanding is that the rate of overweight has been increasing more slowly in recent years, as essentially all the people capable of becoming overweight already have.