@bythewell - I think the best thing a parent can do, though, is make sure they give their kids the best chance of having a healthy body image and also keep lines of communication open so that if anyone interferes with that image, the parent will know it.
I can even remember teachers shaming me when I was in primary school, for being too tall or too fat (even though I wasn't fat at all). And I've had people call out horrible things to me on the street. I remember one of my friends in high school telling me that she regularly had boys tell her that she was ugly.
I mean, almost every child is going to experience things like this and it will probably hurt. It's important to make sure they know that they have support and have nothing to be ashamed of, so that they can process that kind of despicable behavior properly.