I mean in the sense of gaining muscle. I was a skinny, scrawny little kid all my life until I decided to hit the gym and get truly fit, not just skinny. Went from skinny to athlete. True for some maintaining skinny doesn't take willpower, but putting on muscle usually does.  May I also add that if we want fat people to take control of their lives, drop their weight and get healthy, which, if everyone did this, would solve the obesity crisis, we shouldn't shut them out because they once had problems (that were solved!)