One of the coolest characters I have ever seen was a fat mod having Argonian by one of our members here who called his guy "Fish Face". Dude was AWESOME looking. I have never seen overweight/fat characters before Mr. Fish Face but think it would have been cool from a purely RP perspective to have this option available during character creation.
It would be inspiring to be able to creat a really fat Nord woman character who as she progresses in her training to become Dragonborn, is able to lose weight and go from being fat to being Jordis like.
I'd create her at the beginning and give her no stamina, bone break fever and maybe something else so she'd be all tired and weak and slow. Then, she'd train with the companions and start losing weight, increasing stamina and such that she soon becomes a powerful warrior, Dragonborn and HOT.
We have sliders to make old people, we should have sliders for fat people or super skinny people as well.