Good advice given so far....define 'normal'?! It's impossible! If realistically this is the first time in a long time you have rigidly stuck to a diet, and you have quite a bit to lose, then while 3 stone seems a bit alarming in such a short space of time, this is evidently normal for you. Like Mixxy says, unfortunately, soon enough this rate will almost definitely slow down or even stop on occasion. If you are being monitored and you feel ok, then chances are you will be ok. If you are worried, do as Julie suggests & contact you Dr/health care provider.