In this case it does matter. Hydration levels cause massive fluctuation in bioelectrical impedance testing. Also, at bodyfat levels below 15%, the numbers tend

In this case it does matter. Hydration levels cause massive fluctuation in bioelectrical impedance testing. Also, at bodyfat levels below 15%, the numbers tend to be meaningless, even the trend in the numbers. For instance, I have a Fitbit Aria which I use to track weight. It also spits out a bodyfat number. This morning I measured 5.4%. yesterday, I measured 12.1%. Skin caliper testing, DEXA scans, or submersion chambers are the only real way to test at lower BF levels. An eyeball is better than the scale at this point. One look at someone will tell you that they are not even close to 5%. You will see significant vascularity and seperation between the muscles at that level. Only bodybuilders really tend to get there. The typical guy on a mens fitness cover wouldn't likely be under 7%.