Not necessarily. It seriously varies in my experience, and I've been with both body types. Most guys of any body type will be about average. Some bigger guys may have some fat padding their pubic bone that makes their penis LOOK smaller than it is, but you can tell their true size when you actually get physical with them, because that fat is soft, it 'squishes down', for lack of better terms, haha. I actually kind of like that better, in that us both having a little bit of fat there, slamming pubic bones together when things get rough isn't painful.