I've recorded my weight every day since 1 January 2012 and plotted the data in an Excel spreadsheet.
For convenience, I've set the minimum and maximum values on the y-axis to the weights that correspond with the underweight and obese BMI cutoff values for a person of my height. The resulting graphs display some surprisingly consistent trends; a quick visual inspection of the data suggests that my weight on any given day typically differs by less than 1 kg from weights recorded on surrounding days.
I'm wondering whether there is a more precise or standard way to determine the average deviation of individual data points (from the surrounding data) in a data set whose overall trend cannot be accurately represented by any of the typical linear/exponential/power models. (I've considered splitting the data set into smaller pieces and analyzing those using regressions, but such a method seems rather inefficient and arbitrary.)