And, as several people have pointed out below, there can be other physical conditions that contribute to weight, aside from and in addition to emotional issues.

It's all too easy to dismiss any compulsive behavior as an issue of character or will power; if it were a simple matter to just 'put down the fork' there'd be far fewer people with weight issues, and if it were simple to quit, there'd be far fewer smokers. I think part of the problem is in thinking of ourselves as if body and mind weren't integral to one another, setting ourselves up to believe that our conscious minds are not only responsible for, but capable of being 'in control' of the whole complex dance of physical and emotional processes that make up our lives.