Against all advice, I weigh most days (scales record to .1kg), but just to look for a trend. I always weigh at the same time (early morning, after run, shave and shower, but before food). I only record once a week, however. I'm normally heaviest on a Monday or Tuesday and my weight reduces to it's lowest point by Friday or Saturday. My weight the following Wednesday will normally be similar to the previous Saturday morning. It can vary .3 to .4kg between days, but it's the trend I'm looking for. That is usually consistent - up, down or level. Interestingly, I can also reduce my weight by 100-200 grammes by stepping on first with my left foot, rather than my right. If I suddenly see a massive weight loss one day, I can usually put it down to my other half adjusting the zero set point so that the scales tell her what she thinks she ought to weigh...