Get the calipers! I've got a really cheap scale that does the same thing as the fitbit. If you use it straight after coming out of the shower: 35% body fat!

This is my third week back in the gym, and the physiological, visual changes are the most dramatic. That, and increased grip strength has been the biggest change so far!

Objective instruments are sometimes flawed. The fitbit watches in particular typically take ~40 seconds to catch up with heart rate changes during hiit, and when they do; they're not very accurate.

Stay injury free!