I havent really faced this before....I have had MANY comments, and usually follow a simple plan: accept the compliment, dont offer more info than I want to discuss, change the subject!
I have also dealt with comments that were unintentionally rude. Such as the "wow you look great, but dont go anorexic on us!". Ugh, yes that is annoying and uneducated and actually very rude, but the speaker doesnt mean to be rude so I follow the same simple plan (with a possible education opportunity if appropriate).
But this weekend I had what I think is an actual first - a rude comment not at all couched in a compliment.
I went to my neighborhood deli (where I was formerly addicted to homemade blackberry muffins) and one of the owner/workers looked at me like I had a disease. Convo that followed:
me: "hi Lynn, its been a while so nice to see you!"
her: "you have lost a ton of weight" (not in a happy tone)
me: "yup, about 10lbs, feeling great to get the last couple lbs off!"
her: "can I be frank?"
me: "umm, I guess"
her: "you dont look good, you look sick. you looked healthier before"
me: stepping away from register and pointing at legs, jokingly "well some parts need more work than other, thanks for your concern, but my doctor thinks Im doing well and am perfectly healthy!"
Maybe it was the fact it was super early on a Sat am, I had no makeup on, was in workout clothes and hadnt had coffee yet. Im sure I didnt look my best, hah. I also realize I left myself wide open, but I just didnt see it coming!
And frankly with a body fat% in the mid 20s and my weight in the 130s, I shouldnt be setting off people's skin and bone alarms. She is a pretty petite woman herself, smaller than I am for sure.
Has anyone else experienced this and how did you deal with it? I was polite, but it actually irritated me.

I cannot believe some people!
The owner you say? If you were formerly addicted to one of her products and no longer spend lots of money on that product, she's probably just missing the income on her blackberry dope.
If it happens again, I guess you could say something like..."Yeah, instead of blowing my extra cash on your muffins, I'm spending my money on smaller clothes at the boutique down the street. 
