Why do most thin girls get bullied so much?

I've gained weight and I'm 122lbs. I used to be 106 before puberty hit. I'm still slender but some girls at my school calles me "Skinny Minnie" "Anorexic" and "Domt you ever eat? Let me fix you something to eat." "They haven't giving you enough to eat." And "Guys like girls with more flesh on them. Not skinny ass bitches. People are praising bigger girls but criticize us slender girls. I'm 5'2.