Well, somebodies got to stick up for those not present so it may as well be me....
I don't really think the women was really angry at you or low carbers...more than likely she is just frustrated as hell like lots of us have been and many still are. She has tried unsuccessfully to lose weight and failed. Failing can make you stronger if you're positive and persistant but it can make you cruel and angry if it beats you....it makes people do and say thing they wouldn't otherwise say. It's easy to smile when you're winning but it's a real show or character when you can smile when you're losing.
Then again maybe she's just a b*tch