I agree with much of what he said, except the conclusion that he starts with.
Firstly, it isn’t critical to me that I get an accurate bodyfat percentage - is it really 18.2% or is it really 17.8%? I don’t care. What I want to know is my trend… am I averaging lower than last month, or higher? The truth is, only rendering is fully accurate for bodyfat measurement, and you only get to have that done to yourself once. Also, after being rendered, you’re dead, so it’s useless for long-term tracking.
Secondly, I check myself every morning before breakfast specifically so that I get a consistent hydration level. The hands-and-feet scale is very consistent for me; if I re-measure, it may vary by .2% or sometimes .4%, but never more, unless I got a “wacky” outlier which can be ignored. I’ve gotten into a very strict routine as far a procedure and posture to keep it as consistent as I can.
Third, it’s about running averages, not about any individual measurement. The impedance side is less accurate than the weight, but neither is a really good indicator of where you “are,” because where you “are” is always varying. You still need to take an average. Weighing in the morning before breakfast decreases the variation, but it’s still there.
Lastly, bioimpedance doesn’t actually measure fat. It measures some lean tissue, estimates other lean tissue, and assumes the rest of your weight is fat. The result is that increases in muscle hydration increase the reading of “lean” tissue and lower the fat, while decreases in muscle hydration lower the “lean” tissue and raise the fat - even though the fat actually isn’t changing, at all! I’ve been doing this for many years, and I can see large, clear changes based on my diet - when I’m on a PSMF or a three-day fast, my muscular hydration levels due to depletion of stored glycogen causes enormous differences, but I’m well aware of them. If I stop lifting weights, I also see the change, and if I do a really heavy workout and my muscles are swollen, I see the difference - but the key is that I understand what’s happening, and I look at my graphs for long-term trends.