She is bullied for her obesity. Because of this, she starts to view her body in a negative light, so she goes to desperate measures in order to lose weight.
Storyboard Text
Maybe they're right...
Gurl, you fat!
You could stand to lose more weight -- like tons more.
I'm too fat for anyone to like me.
I ate too much. Now I have to get rid of all these extra calories.
*barf barf*
*pant pant*
I really want to lose weight...
*sweat sweat*
You look great! Did you lose weight?
Yeah, I've lost 20 pounds.
You go girl!
Wow, I'm at a really good weight right now. I feel amazing.