You see.. I'm one of the few guys who doesn't really care if a girl has some weight. Of course I'm concerned if her health is in danger, but as long as it isn't overwhelming, sure, why not. I'm not perfect either.
Anyway.. I don't entirely dismiss the idea, but come to think of it. Gragas fills a archetype - Gluttony. One who does not stop to seek for greater things and more things to consume. And this is Gragas, and as his Lore states, he was searching for the perfect alcoholic drink, thus is that "fat".
Now how can this female chubby be fat? Does her battle skills or fighting technique base on overweight? I've created over 45 Champion Concepts, yet I don't have the slightest idea what a chubby female could provide in a battleground..
If we make that certain Champion too fat, it'll bring some pain to ones eyes. Like..
http://static.fjcdn.com/pictures/Fat_d368cb_2599845.jpg
A chubby Champion could fit when it is made as a monster - similiar like.. I dunno.. maybe Ursula from The Little Mermaid?
http://raivenne.files.wordpress.com/2012/06/ursula_bad_ass_03.jpg
Maybe someone who can use her voice to deal damage or support the team? Similiar to the opera where most "bulky" female do sing with a great voice.
Anyway.. that's all I had to say.
As you're a "chick" and had the bravery to show up on this strange place full of nerdgasm and crazyness, I would give you 100 cookies for that. Unfortunately, I only have 99.. you ask why?
http://28.media.tumblr.com/tumblr_lzrot6mWVo1rq7hp4o1_500.jpg