That's the whole crux of the issue. If you're a powerlifter or some shit like that, that's one thing. But, if you're fat because you overeat and don't move enough you're not going to develop muscle proportional to the amount you weigh. It's like sticking a 500 horsepower engine in a dump truck, that thing will probably haul ass in a car, but the power to weight ratio just isn't going to be the same thing in the dump truck.