I was very honest with both of my children. While they are a bit younger 8 & 6, I wanted them to know up front that I was having surgery because I made some poor choices over the years that caused me to gain weight and I needed to change not only for myself, but them as well. I let them know that alot of our "old eating habits" were about to change. We had our struggles with "why do we have to eat this" at first, but now they both are right there on the healthy food train with me!! As far as the exercise goes, they are they ones keeping me encouraged! They love that I can run with them now, and I constantly hear, come on Mom......just a little further, when we are at the track!! I LOVE IT!! I say make your daughter a part of the change, when she sees the new choices you are making, I bet she will jump right on board with you!! Best of luck in whatever decision you make