I'm not a pro on men's looks but I really don't think 6'3 300lbs is all that fat either.

Everybody (both men and women) have their type. I'm 6' 180lbs and some women consider me too skinny. Other's stick their phone number in my pocket at clubs and others wouldn't be with me if I were walking through a womens prison with a handfull of pardons.

All a matter of taste, there's someone out there for everybody. Chin up!