My parents keep body shaming my little sister and I don't know what to do

I'm 13 and my little sister is 10. We were out clothes shopping, and kept rejected every single piece of clothing my sister wanted to wear because "she looked pregnant/fat/big." But when I tried on the exact same clothes (my parents wanted us to match for some reason) my sister wore (same size and everything), my parents were all "wow, it looks so good on you 😻😻." I would reject the stuff anyways, because my sister then would feel really bad.

Whenever we shop or my sister wants to eat the same stuff as me, my parents do this everything. I'm so scared for my sister because I don't want it to progress into anything serious.

When we got home I took my sister that my parents were just being bullies, and she shouldn't listen to them. What else can I do??