Idk what to say to my sister losing weight.

So I FaceTime with my sister (she doesn’t live nearby) often, and every time we do she brings up her weight loss. Now, I can sympathize, because I was vocal about my weight loss when I lost a lot, but I often left it to others to bring up- where as she always is the one to bring it up. Honestly the changes seem subtle to me, which is why I don’t notice, because when you FaceTime you don’t exactly see someone’s body so she looks about the same unless she points it out- which is why I don’t mention it myself usually. I also don’t like the way she talks about her body- especially when I have my daughter around, as I don’t want my daughter to grow up feeling insecure about her body, I’m very active in making sure I speak positively about my body and hers. There’s also the problem that my sister doesn’t exercise, doesn’t eat healthy (just less), and is on diet pills- which is the only reason she’s loosing weight (trust me I know this as I know my sister and her past issues with weight and I know these things to be true and I’m not just assuming), and I think that’s a horrible example for my daughter to hear about and for her own teenage daughters to see (especially as she teases her children for being overweight). On top of all of this she kind of throws it in my face and tells me things like “you just have to eat less” and such, when I am LITERALLY so pregnant I’m about to have the baby in a few weeks, I eat healthy in general, and before pregnancy I was smaller than she is now. I also have lost weight in a healthy manner many times in my past with eating healthy and rigorous exercise (I’ve even taken a class on nutrition and exercise and she knows it). So she should know that I don’t need “tips”, as I couldn’t use them now even if I wanted to, and I have LITERALLY been giving her advice whenever she asked on losing weight for YEARS and she never took it even though she asked (and no I never shoved that in her face).

Part of me thinks/knows all of this stems from her insecurities and the fact that me and our younger sister are both pregnant, so it’s finally like her time to not be the biggest sister (she always has been and always resented it).

I know she has some problems mentally, and really I’m just venting about the way she’s handling things, but really I need help.

Idk what to say to her about it anymore! I tried to brush it off and be positive; “that’s great/I’m happy you’re happy with your results/I wish you the best on that path” those sort of sentiments, but it’s at the point where I’ve said all I could say and I don’t want to hear about it, and I don’t want my child to be hearing about it, because it’s not good for our mental. What do I do from here?