Talk to the Teacher Hun, I did and it helped. I also got lots of pictures of children and sat down with Ruth and showed her the reason why people are different shapes and sizes. We talked about what beauty really is and what really is important when looking at each other.
As she has gotten older we talk about body image and the down side of advertising and pressure to conform. Ruth is now very confident about her body and now that she has lost the baby weight she is far from being the chubby little girl she was.
Ruth and now Caty, held on to her Baby weight a tad longer than there friends, runs in our family,LOL
However by the time she was 7yrs she was actually a lot slimmer than the girls that were taunting her!!!!!!!!!!!!!! However thats by the by.
No point in speaking to the parents, it may either get them upset at you, or the idea of thin/ fat could come from home in the first instance in which case your flogging a dead horse, if you get my drift.
You could use the photo section of minti to look at pictures of children and see the beautiful diversity of kids, and how they all delevelop at different ages and stages,LOL.
I will post a pick of Ruth for you as a six year old and a seven year old, so your Daughter can see the futility in looking at peoples weight to judge them if that helps.
The school also has real Models come in for SPI (Social and Persoanal Interaction) all different shapes and sizes. They showed us how, their photographs were altered for publication and all were made to look much thinner than in real life.
Don't be afraid of being open, knowledge even in youngsters is a tool to confidence.
I also looked at a picture of your Daughter, and what a stunning little girl she is. It is such a shame that parents have to deal with this sort of thing at any age.
Best Wishes. Luv Winnie.xxxx