Admittedly there's a reason why fit guys are used in advertising- they conform more the societal norms of attractiveness. And yes, fit people would have an easier time on the surface than overweight guys...
BUT- that's just part of the story. There are other factors which in a way are more important- like your confidence, how you carry yourself, your sense of humor and overall personality. Just don't get caught up in the whole trap of going after guys who are fit and looking for fellow fit guys. That's just asking for rejection. Go out there, have fun and you'll attract the attention of people who are into you. The more people you meet, the better your chances of finding someone who'll find you attractive.
That said- it never hurts to lose a few pounds if you can- more for health than anything else.
