It's almost funny how much faith we put in bathroom scales, considering the fact that they're cheap, simple, relatively inaccurate, and certainly not precise measuring devices.  The mechanism inside a scale is likely either a spring or a strain gauge, both of which are affected by repeated use, temperature, and likely humidity.  Plus, it's a standard and necessary practice in industry to calibrate measuring devices at least daily, if not more often.  A digital scale that simply zeroes itself doesn't mean it's calibrated.  Nonetheless, I gained two pounds this weekend according to my bathroom scale. #science