nope...
some of my friends are more of a larger build, especially one i know, and dam he is very confident. and alota girls like him, probably because hes so funny.
some of my friends are really skinny, and they are not the most confident. and me, well id say i was always confident, before when i was skinny, and now, when im fat.
however i do know a friend he was a bit chubby when we were small, but after he lost weight, he had become more confident and happy...