Fitbit Aria

Does anybody use the fitbit aria? In general, it does what I need it to do and mostly bought it for the auto-logging via Wi-Fi because I like having the data.

I also recognize that, while the BF calculations aren't completely accurate, it's good enough for what I need. I don't really care whether it's calculation is off by 3-5% so long as it's consistently off by the same amount.... which I have found to be true.

So here's my question. Lately, I've been noticing a familiar trend. As soon as I hit a new low in BF, it'll start rising consistently by 1-2 tenths of a percent until I hit my previous plateau. It'll sit there for a week or two and then suddenly drop by 1-1.5% and then it'll start cycling up again. Over time, the trend is definitely in the right direction, but it's just a curiousity. I'm just wondering if anybody has any opinions/ideas on what it's measuring to produce this trend. It's far too linear for me to chalk it up to a home scale's inaccuracy. It's clearly basing it's measurement on something that is changing within my body throughout the day. The last bit here is that I get on the scale everytime I go to the bathroom (TMI, I know). How does peeing make my BF% go up? It also does this after #2 as well.

Sample data points below:



Today at 6:13AM
147.7 lbs 18.0% fat


Tuesday, May 6 at 11:30PM
148.9 lbs 17.9% fat


Tuesday, May 6 at 10:20PM
149.3 lbs 17.8% fat


Tuesday, May 6 at 8:46PM
149.3 lbs 17.7% fat


Tuesday, May 6 at 6:44PM
148.7 lbs 17.7% fat


Tuesday, May 6 at 5:56AM
148.4 lbs 17.7% fat


Monday, May 5 at 9:41PM
149.5 lbs 17.5% fat


Monday, May 5 at 5:47AM
149.2 lbs 17.3% fat