WTF, my sister is on an extreme diet... woah wtf?

you should definitely talk to your parents. my best friend in high school went through anorexia and it was really hard. she's only just now getting to a point where she's eating well. she's 22 and i was so happy to hear a few weeks ago that she had 2 eggs for breakfast. you should definitely make sure of what's going on now rather than letting it get to that point.