bad example with overwhelming pressure for children?

How incredibly rude that this is being said! The person who said this should be deeply ashamed!

Oh my goodness... I'm a teacher... I don't think it's very normal to communicate like that.
First of all, everyone actually knows pretty well whether their own weight is healthy or not. Even children know if they are a bit too heavy.
Secondly, I'm not there as a teacher to judge others. Least of all parents... and certainly not to give unsolicited advice.
And if you do want to discuss nutrition as a teacher, you should indeed do so without the child present. Or... you do it by asking questions.
But hey... first of all, there are many stories going around about the relationship between sugar and behavior... and opinions on that are divided. I think too much sugar is unhealthy... but not that you get hyper from a piece of candy. I think too much sugar and fat isn't good for your body... and I do think it's important to take good care of my body. And that works out better in some periods than others... and right now in my pregnancy, it's not working at all.
Am I then a bad mother-to-be? No, I don't think so. I do my best, you do your best. And you know pretty well yourself whether it's actually something to improve or not. If you want to eat a bit healthier for yourself and your child... then do it for yourself and your child! But what that teacher thinks... that really doesn't matter.
You know it yourself... and act accordingly. And if you find that difficult... then go see a dietician without your child and chat with this nutrition expert. You'll find your way naturally.
And if you're fine with it like this... that's fine too, then just keep going!
Oh... and sometimes it helps enormously to drop your frustration on my forum for a moment.. hopefully it lifts and you can let it go. Teachers sometimes interfere unnecessarily with parents... as a teacher, I dare say that! And they aren't always right...!

I would really have a conversation about this. This is going too far.
I can't imagine ever saying something like that to one of my parents.

I do think you can file a complaint against this teacher. Or at least request a conversation with the teacher and the school principal present. This is a serious breach of communication and professional conduct by this teacher. Hopefully it was unintentional, but it is hurtful and completely unacceptable in front of your child. The teacher undermined your parental authority here and humiliated you in front of your own child. That really can't happen, and an apology is in order. I understand the teacher was looking for an explanation for your child's behavior, but then he/she should have sent your child out of the room for that part of the conversation. And weight says nothing about being a good or bad role model for your child. You don't criticize parents in front of their children; there's no debating that.