Don't worry about trying to stay on program at the con. Just enjoy! You can be aware in the back of your mind and avoid completely ruining yourself on goodies...but do not obsess. Just be extra sure to keep drinking your water! I've been there and done that several times. I can't remember exactly how much you've lost total...but I am sure that you are on target for losing 1 to 2 pounds per week.
WW Week 12