T Nation

Electronic BF Mesuring Devices...

The trainer at my gym approached me with this airplane stearing wheel looking device and asked me if I’d offer my stats; weight, height, age, and told me to hold tightly to the metal parts and it after a while it apprantly calculated my BF%.

Does anyone know these devices? Are they accurate? I’m suspicious. It said I was 1.8% lower than I thought I was.

Anyone have/had any experience with these?

Those things can be really off sometimes. I’ve heard the handheld models are even worse than the kind you stand on. Here’s some info in this t-mag article http://www.t-mag.com/nation_articles/208comp.html

Three days ago I received a Tanita BF-626 (the 612 model, which was in T-mag some time ago, is old and no longer available), which is a scale and a body fat monitor. This specific model has two modes, adult and children, then seperates as to sex. Another excellent feature is it further seperates the modes into (1)adults and children with inactive to moderately active lifestyles; and (2) adults with athletic body types – which be us. I have compared the BF %'s and BW calculations of the Tanita BF-626 (cost $78, which included shipping) to results which I have paid $50 plus each to obtain, and the readings are very, very, very close. I do recommend the Tanita BF 626.

I am suspicious of any device which asks your age to measure your body fat.
Seems to me, when this occurs, a sweeping conclusion is on its way!

We had one of these at my place of employment. When I entered my stats, it stated that I had 12% body fat. When I replaced my real age (47 at the time) with a false age of 30, it said my body fat was 9%.

On further examination, I entered an age of 55 and got a body fat reading of 15.7%. It seems that you are penalized for being older regardless of your true body fat.

About a month later, wanting to get an accurate reading, I was measured by our college’s wrestling coach with a set of calipers. I was the exact same weight, and training the same. The coach measured me at 8.9%.

It seems that when I entered the age of 30 into the electronic body fat analyzer I got the most accurate reading (9%). Anything below that was inaccurate because the reading was to low. above that figure and the reading was to high.

When they come up with an electronic body fat analyzer where you do not have to enter your age, you will know that they have taken a step in the right direction.

they dont measure fat they measure water (or more accurately bio impedance, that is the electrical impedence from your body when a small charge is jolted through you).
They are an educated guess at best and are pretty crap if you are outside normal ranges (ie below 10% or above 18%). if you are dehydrated (eg from exercise or getting on the guinnes the night before) the measurement will be off, saying you are fatter than you really are (even tho you prob look leaner. likewise if you are holding water (could that time of the month, or due to increase salt intake etc) then it could say you are leaner even tho you look like crap.
i still prefer calipers or photos. these measure/show what we want to mesure/see, and are more usefull when assesing change.

I got the Tanita BF-626 as a quick alternative to calipers and to high cost measurements by external sources. This machine uses the BIA method (Bioelectrical Impedance Analysis) and the results, as mentioned earlier, are very, very, very close to calipers and other more expensive alternatives to measuring your BF %s. I am 57, the wife is 43, and we have a 19 year old daughter and a 17 year old son. The Tanita BF-626 works for all four of us, and provided excellent readings. And yes, we are also concerned about accuracy and the use of built-in parameters. But it works as well as any other alternative used in the past.

Stew, the accuracy of the 626 may have to do with where a person carries the majority of their BF; legs (in a lot of women) or belly (in a lot of men) or just the fact they’re at a low enough number. I had a DEXA BF test done recently (which as you know is about as accurate as hydrostatic weighing), and my Tanita 626 reports my BF to be 7 or 8 percentage points higher than the DEXA.

The bioimpedence scales are also subject to multi-point fluctuations due to levels of hydration, whether you’ve worked out or not, and how recently you’ve been to the bathroom.

Actually, I like Zeb’s idea re the age. Maybe I just need to adjust mine downwards a decade or so. (grin)

ZEB, the reason they ask for your age is because as you age you hold more visceral fat (inside, around the organs) as opposed to subcutaneous (under the skin) fat, so the calculations try to take that into account. I agree in ‘dropping’ your age, I usually drop my age by about 10 years, and that jibes with my own measurements.

Zan,

I understand that they want to add a persons age, based upon holding more fat near the organs the older you are. However, that is still an assumption on their part.

They are not measuring that alleged fat near the internal organs. They are assuming that it is there based upon your age. There is the major flaw with the electronic body fat analyzers!

I am 48 years old and 190lbs. I can run a mile in around six minutes. Put 225 pounds over my head in a clean and Jerk. And do 31 dead hang chin-ups. Do you think that they should assume, by virtue of my age, that I have as much fat near my internal organs as a 48 year old couch potato?

Again, the best way to use an electronic body fat analyzer is to first get your body fat taken by a profesional means. Then, calibrate that with the proper age on the electronic unit. As I stated, in my case the proper age to enter was 30, which made the analysis come out to the 9% figure which corresponded to the professional analysis.

There are many formulas to calculate one’s bodyfat. If you are using the calipers, the numbers are merely useful for tracking trends, nothing else.

If you want an exact BF% with an error of 1%, you need to do the water submersion.

Just to give you an example, my caliper bodyfat measurement ranges from 9.7% (7-point measurement) to 12.1% (3-point measurement), to 13% (5-point measurement), to 17.5% (9-point measurement). There are more formulas using diferent sites than you can shake a stick at and they all differ in results.

Who’s to say wether the caliper reading was an accurate representatino of your real bodyfat? Remember, it’s ONLY useful for tracking trends and give you a general idea of where you stand in comparison to 2 months ago.

Additionally, different individuals store fat differently. Where one individual with 20% stores a large ammount of fat in the suprailliac, another with the same bf% may not. This will lead to different readings.

WOW,
I am so glad that I read this thread. I get sooooo frustrated with the Tanita scale that we have here where I work. I never thought about the whole “enter your age” concept. Now that I think about it…it does seem a little shady.

In any case, I would love to invest in a skin fold caliper. Does anyone have a website where I could find a high quality one?

Well ZEB, I didn’t say I AGREED with the idea, just trying to explain the reasoning. I do agree with Diesel that any measurement is only good for comparison with yourself.