I was lately interested in learning how the human body weight changes through out the day. Like, how much weight (may be in just 10s of grams) is lost during sleeping, after bathing, after workout and like that. For that I would require a highly precise scale. But most commercially available scales' precision is only upto 100 grams which is not useful for my purpose. When I dug in further, some industrial scales do provide upto 10 grams precision but they (for 100 Kg max) cost in the range of $2500, which is every expensive. I am looking for some cheaper means of measuring human body weight fluctuations precisely. There are kitchen scales for just $10 which have precision of 1g but they can measure only upto around 5Kg. I can see that its much more difficult (and hence expensive) to have the same precise measuring ability over a wide measurement range. So, If my weight is going to fluctuate by, lets say only about +-2.5 kg, can I some-how modify the cheap kitchen scale to work around the point of my average body weight? I do have electronics and micro-controller knowledge, but don't have any knowledge about the weight sensor. And, at last, does anyone know about any research publication/works about this quantified changes of human body weight everyday?