Body shaming little sister

My little 9 year old sister told me today she thought she was fat. I told her what anybody would do saying she definitely isn’t and that she shouldn’t care about what she looks like. She replied with you are just saying that because you’re my sister, people probably don’t think I’m cool. I almost broke down into tears. She started naming her flaus. I am trying to let her know that this is not true and that beauty is in the inside. She is actually very skinny.

She’s about 64-68 pounds I really don’t know what to do advice to dealing with her body shaming self??😭