The biggest problem comes down to the day and age we live in. Most of the people out there are shallow, unable to relize that 20-30 years down the line, very few of us will look physicaly atractive.
As far as sex with the fat girl goes. This is my experience. I prefer them. Heres why. Because of the stigma thrown on them for so long, they are more eager to please. They want to go that extra mile to make it worthwhile because they have time and time again the subject of the one night stand. I've had women who fall right into the catagorey that society has declared to be "in", and i've had the fat chick. 10 times better witht he fat chick.
besides as a fat guy, the fat chick is more likly to want to continue at least talking to you.