Some people would take her comments as a complement. There are posts here at 3fc where members wonder why nobody has said anything about their weight loss.
That said, I completely understand why you don't want to discuss this subject and you certainly don't have to. I love the idea of changing the subject, which Lovely recommended.
If you want, you could also just say, yes, I did, but it's not really something I'm comfortable discussing.....and then change the subject. Some people just don't get hints, unfortunately.
Finally, you can just try to avoid her every time she's around, but then that would probably be kind of annoying for you as well.
First goal: under 180:
Second goal: 175 or below:
Third goal: 168 (no longer overweight):
Fourth goal: 160 or below:
Final goal: 145-155 (not sure if this will ever happen):