Body Composition Analysis (Why I hate this crap!)

What people tend to forget about ANY electronic fat testing device (whether it be the Tanita scale, or the hand-held thing we all can't pass up at the Sharper Image), is that the results are based on a circuit of electricity that essentially finds the shortest path back to the receiving electrode. Scale-based devices essentially OVERSTATE the presence of body fat in the legs, hips and "rump", because the electronic signal flows up one leg and down the other. Hand held devices create their circuit through one arm, around the chest and back up the other arm (overstating upper body fat stores).

The only true measure of body fat is based on fluid displacement (aka - the "dunk tank"). Of course, this all goes without saying...

All of that said, when the new fangled Tanita scale tells me my 38 year-old body has the metabolic age of a 19 year-old, I'm buying TWO!

~B

"if you run for yourself, you might let yourself down, but if you run for someone else, you'll never let them down..."

Baselbutt - I think that is the entire point of my post. I was measured using the Underwater Weighing method and it was only .5% different than my Tanita. That's what made me so self-concious about the #, because I always assumed the bioelectrical impedance method used by the Tanita overstated my % body fat. In this case it didn't.

Here are things to consider too... my residual volume was estimated, which increases the error associated with the test. Essentially making it no better than a skin-fold assessment assuming you have a reliable tester (which is a big assumption in the skin fold method.)

Anyway the moral of my story is that it's all crap at some level. Having worked in the public health / health promotion field it's amazing how we like to categorize things to make us feel better. If at 5'6.5" and 138 pounds, male, 28 years old - I get a response saying that my weight puts me in the "unhealthy" category, then I want to know who decides what is health and unhealthy. Most likely some overpaid doctor that hasn't exercised in 10 years and is completely out of touch with their own bodies.

Thank goodness I'm not a female. I can only imagine the pressure to obtain a body type that is ultimately too thin and very unhealthy.

PS - I'm not sure why the entire posts are not coming through? Is this an issue with the "share your blog" function at yourrunning or with my feed? Guess you'll have to make your way to my blog to read the entire post for now.

Hi Gary,
I had some blood work done which also surprised me, in that it confirmed a Tanita hydration reading. Until that point I hadn't taken the thing too seriously. I have one of the stand-on scales that gives bodyweight, bodyfat % and hydration. As a basic principle, there is no point measuring your bodyfat % on one of these things UNLESS you know your hydration status.

Given that I like gadgets, so I'm a little bit biased, I don't think these things are crap, exactly: it depends how you use them. It doesn't really matter whether they're accurate or not; the important thing is that you can use them to establish a trend. I have no idea what my true bodyfat % is, but using the Tanita I can watch it week on week and see whether it's stable or going up and down (taking readings at the same hydration level). That is really valuable information.

It's the same with the weight and hydration., It doesn't matter to me what the "true" figures are -- I'm interested in whether the figures change or not and whether they are trending up or down.