What should I do about my dad?

So, the thing is I'm 14, and I'm mostly concerned about my physique. I'm always checking myself out on mirrors, trying to find things that I dont like, in order to change them. I am a pretty girl, and most of my school friends think the same thing, but I have always been against my body, especially my legs. For some reason, I don't like them. Through time, I have learned to enjoy and be comfortable in my body, but there's a bit of a problem. My dad is always making some rude comments about my figure. My tween sister is skinnier than me, which she has been trying to solve by eating much more food and becoming healthier. Because my dad sees my sister so skinny, he thinks i'm over weighted or something, when I really need to gain some more pounds for me to be in a normal range. Some of the comments he makes, are about my legs, which really hurts me. He sais things like: "Hey, um, your legs are bigger than they used to be.." or " Don't eat candy because that makes people fat" IM ONLY 14!!! I'm actually having some trouble accepting my body, and he's making it much harder! All I want to do is cry. He's my dad, and he's supposed to be helpful, not the other way around! WHAT SHOULD I DO? AND HOW!