I just increased the dosage of kid's painkiller O gets for her headache based on the weight she was at the doctor last week, and she got all worried because of the increase. I hate the culture that makes a 10 year old assume that her weight gain is BAD even when she is growing! (And while this would also not be particularly rational if she was heavy, the girl is *skinny* and that still doesn't mentally override the "oh no I've gained weight" thought.)
Fat as an insult is traded frequently around the playground, too. At this age it doesn't appear to be related to actual fatness, though I can't decide if that is better or worse.