Its recommended that you should aim to lose no more than 2lbs per week. Except when I weigh myself from day to day my weight can fluctuate up to a pound or two. I always weigh myself in the morning on an empty stomach so I know it is due to undigested food. My guess is that it is simply a fluctuation in water weight. But since this happens, how can I get a consistent/accurate measure of how much weight I'm gaining/losing?