I'm a guy, and while I'm not obese (at 5-8+ I've ranged from 150 to 180, and I'm presently closer to the latter than the former), I've NEVER had a flat stomach. (Well, maybe I had one when I was 6 or 7 years old.)
It must be great to have a flat stomach... if I ever have one, I'll be pleased as punch (this might sound…