Do I Care?

Recently, a growing number of people in my family have expressed concern about one particular family member's health. I'm just gonna keep it real, the girl is getting fat. We're talking she is 5'9" and used to weigh 125 lbs, but now she is probably close to clearing 200 lbs. Now, we all gain weight as we get up in age but when you can't find a nice dress in your size, you are constantly shoveling food in your face, throwing temper tantrums like a 5 year old child when you think someone is going to take the last serving of your favorite desert, there is a problem. We all talk about it, we watch her in action and shake our heads in disgust. But no one will say anything to her because of her fragile mental state. She's easily offended and proclaims to be happy with her weight in one breath and then talks about how she lost 8 lbs. over the last 2 weeks in the next.
When my beloved overweight family member asks me to make her some more banana pudding after she ate the ENTIRE 6 servings within 24 hours the last time I gave her some, do I brush her off? Do I explain why I REFUSE to contribute to her problem when she doesn't think she has a problem? Do I try to get her to see that there is a problem? Or do I make it and let her eat herself into an oblivion?
The problem is she has some serious health issues and I don't think being overweight is helping them at all. She claims the doctor says she is a normal weight for her height but, to me, all of that jiggle and flab CANNOT be normal.
My mother used to tell me that people who care about you may tell you something that you don't want to hear but they are telling you for your own good so you can improve yourself. I live by that motto. If I said something out of the way, let me know. If I wore something inappropriate, let me know. But when the person you care about is EXTREMELY sensitive, do you still tell them something they don't want to hear? When you hear people talking about her all the time, does she need to know?
The question I ask is do I REALLY care about her if I don't say something in order to spare her feelings or should I expect her to understand that love hurts and I am only hurting her feelings temporarily so that she can better herself?