Why can underweight ppl get mocked and its okay, but if overweight people get mocked, its not okay?

[Emma]

I'm 5'5 and 85 pounds. That makes me underweight. I've always been this way, due to my metabolism, which I got geneticly from my mom who was the same way (she still is thin.) in middle school and highschool. I'm not anorexic or bulminic, or whatever. I love food. I actually eat a lot.

Today, on facebook, there was this picture. It was a drawing of a overweight girl, and normal weight girl, and an underweight girl. The caption was "All girls are beautiful no matter their size." I read the comments, and most of them said "The skinny girl is ugly. That's unnatural." or "Don't call the fat girl person ugly! The skinny person is unnatural, she's to skinny!" and stuff like that. Another comment said "Don't call the underweight girl ugly. " And she got tons of criticism? Why are people like this?

I've been called twig, skinny, and bulminic (Not anorexic- I make sure I eat a lot in front of people to show them. I even beat a fat boy in an eating contest! hahaha. oh wait. skinny people can't make fun of fat people. huh.) and stuff like that. it doesn't bother me that much, but being called "unnatural" bothers me a little.

So, why is it okay for fat people to make fun of us skinny girls? I can't help my weight- yes I've done the weight gain stuff, but I only gained about 1 pound. I can't help my weight. The doctors used to make me eat raw eggs to gain weight (Farm fresh eggs- I live on a farm. ) thanks.