In SAO, the nervegear shows what your body looks like too, so is there any way someone could get more buff in the game even when starting with a chubby avatar?

Well I mean look at Kirito. He was the strongest player in the game and never looked any bigger then a thirteen year old. I don’t think skill level has anything to do with your physical appearance, and normally strength and exercise is what makes you bigger or smaller. Everyone in SAO was getting stronger, but their bodies weren’t changing.