I think it goes the other way around -- once people get overweight, they stop exercising. When I was overweight (I've lost about 80kg), just walking around the

I think it goes the other way around -- once people get overweight, they stop exercising. When I was overweight (I've lost about 80kg), just walking around the shops was a significant exercise, I'd be short of breath. Now I need a 15 mile bike ride to achieve the same level of exertion. Also, after any kind of exercise it used to be every joint would hurt.