I weigh myself once a day, and attempt to keep the conditions the same. Where i’m obsessive, is entering the data in a spreadsheet, then plotting it. I have the daily number, a 3-day running average, a weekly average, with a couple different plots. I haven’t tried to fit a curve yet - wait, yes, I did twice estimate a straight line, to predict when I’ll hit my targets. I noticed that the downward slope increased after gardening season began. :) I did weigh myself throughout the day once, to see how much the daily routine affected my weight, because my starting number was the weight recorded in the doctor’s office last November, where I was fully dressed with shoes on, in the early afternoon. Based on that, I adjusted my starting weight down 1 pound( for the shoes).