Repeatability is stated as +/- 1% BF, so yes it could be used to track trends in fat loss or gain. That said, it is important to do everything possible to get repeatable readings.
Retesting the same time every time, same hydration levels, clean feet and contacts, yada… yada… yada.
It may also be wise to occasionally check to see if the scale is weighing correctly. Either weigh yourself on a known accurate scale then compare readings with yours, or use weights with a known value to test the scale.
Tanita does have calibration procedures for alot of models, but understood from talking with their tech support that they don't normally recalibrate homeowner models ... the cost is likely as much or more than a new scale...something to check on... calibrating these requires having accurate weights and certain resistors on hand... resistors come in different tolerances so if anyone wants to calibrate at home, get the most accurate.
The techs were very helpful in sending me cal procedures for a couple of models.
I read a website awhile back that gave accuracies for the different methods of BF analysis. Unfortunately I don’t recall exact figures for some reason either +/- 5 or 7% BF comes to mind for calipers, I don’t recall that the number of sites tested was quoted. I also don’t recall the url, but the info is out there, and those figures should be confirmed.
(Afraid I’m only anal about committing certain things to memory … hope some of that helped)
one last thing… I would recommend not keeping this item in a humid bathroom.