it could be all sorts of things, I always make sure when I weigh in that when i go I'm wearing the same thing, same shoes etc always go before i have had my shake and before i have drunk anything that day. I am a serial naughty weigher inner and the difference between getting weighed first thing and last thing in a day can be as much as 6lbs easily, you can also loose 2lbs just having a wee, I also know that my pyjama's weigh 2lbs and the new skirt i bought the other day weighs 3lbs lol. I told you i'm a serial weigher inner lol. Does your pharmacist keep the scales you weigh in on in the same place coz if they put them away and bring them out again that can effect their accuracy, also. Anyway what i'm trying to say is that it may well be not as it appears at first glance try not to be gutted although i completely understand that that is easier said than done x