Libre is an excellent weight tracker for the android. Problme with it is that it is not well documented.
I got interested in the app after Looking at the Hacker's Diet . Especially the section on using xponentially smoothed moving average with smoothing constant 0.9 and trends. This appealed to me since there is a lot of noise in my weight plot.
I don't know how misnomer1 on myfitnesspal got the formula for Libre, but it corrisponds with the Hacker's diet. If you look at the equation and instead of saying 'days' but Alpha or Smoothing constant, it is all the same.
So, instead of thing "days", think smoothing constant. Changing the advance setting for smoothing days to 10 days, you get the same results as the Hacker's diet.