Why Exercise Won't Make You Thin

In his 1984 novel Thinner, Stephen King creates a character who is cursed to lose weight until he disappears.  In 2009, the curse on America seems to be in the other direction.  But is exercise the solution?  Time magazine explores why we're exercising more, but still gaining weight.

http://www.time.com/time/health/article/0,8599,1914857,00.html