Absolutely do not mention anything to your DD about her weight!
After DS was born I started gaining weight, no too much, but as I'd always been skinny it was very noticeable.
My mum started by gently reminding me that I could do with dropping a few pounds, which upset me, so I headed for the nearest biccie tin/packet of crisps/bread bin etc!
Her next move was to try emotional blackmail, the 'what if you get so fat that you can't run around with DS'?
When that didnt work, she started trying the humiliation thing, if we went out for lunch, even if I had a salad, she'd loudly comment that I 'shouldn't be eating that'!
All she succeeded in doing was making me dislike spending time with her, which was really awful as we'd always had a very close and loving relationship.
She suffered from a life limiting illness, and as this progressed, I took long term unpaid leave from my career to care for her, which was difficult in the extreme, she became totally obsessed with my weight, apart from her own illness it was her main topic of conversation! Every evening, I went home and ate everything I could lay hands on, often standing in the kitchen crying whilst stuffing my face! It didn't matter what DH or DS said, the only thing that made me feel better was food!
I was eventually diagnosed with depression (no surprise there), and after treatment started I managed to get my food cravings under control a little, but even though mum could see that I was losing weight, it wasn't fast enough for her, so the comments continued!
Mum passed away almost seven years ago, but I didn't start losing weight 'properly' until finding out that I was to become a grandmother, proving that the weight loss happened when I wanted it to, not because someone else pointed it out to me!
So, please, please, please, don't mention it to your daughter. I'm not saying that you'd become obsessive about it in the way that my mum did, but if she is 'comfort eating', you run the risk of making her much, much worse!
Sorry that this has been an essay, but it's a subject that I have much painful personal experience of! X