BIA b.f% measurement

HASH · 05-07-2002, 12:21 PM

I just got a Portable Body Fat Monitor, (type: OMRON BF302, Dutch made).

It uses (BIA) Bioelectrical Impedance Analysis; ie: it sends an electrical pulse through your body (after grabbing it in both hands); it also takes your height, weight, age and gender as inputs. It is supposed to be very accurate.

As I was skimming through the instructions, it says that bodybuilders & intense athletes might obtain a wrong indication of bf%, but it would be helpful to monitor changes in body fat.

I am 5'10 and 170lbs, arms around 16";
1) Would this give me a misleading bf% measurement?
2) How unaccurate can this measurement be for a guy in my size?
3) Will it overestimate or underestimate my bf%?

Please post any correct or incorrect measurements experienced when using BIA method...

Thanks

Here is a picture of how it looks!

Ice Man · 05-07-2002, 01:36 PM

If you squeeze it tight its only like 2% off.

**fitnessman** · 05-07-2002, 04:38 PM

Not real big on any of those, so I really cant comment a whole lot.

I am lucky though, I can get tank tested any time I wish for free. But if I couldnt I'd be in the same boat as you.

HASH · 05-07-2002, 10:41 PM

thx guys,

anyone else? any experience with such thing is appreciated

jverch · 05-08-2002, 06:49 AM

I think the best use of those fat monitors are relative BF% changes. Use it under the same circumstances every time and you can track the movement of your BF%, but I don't think I'd trust it for an accurate absolute measurement.

tangun · 05-13-2002, 04:22 PM

I hate to be negative, but in my opinion bioelectrical impedance is a poor way to measure bodyfat. Not only is it highly inaccurate measurement to measurement, but there are many factors like hydration level that will skew the results.

After many years of bodyfat analysis on myself, friends, teammates when I was in HS/college, clients, etc. I've come to the conclusion that the best way to measure bodyfat is to have a professional do it (or a properly trained wife, girlfriend, training buddy, etc) with a very high quality skinfold caliper after your morning piss. Lange makes some nice ones, expect to pay several hundred dollars for a properly calibrated, quality caliper kit. I've found these to be just as accurate, if not more so, than even underwater weighing.

My 2 cents.

IPR · 05-14-2002, 06:50 AM

I have used for the last 4 yrs a BIA set of scales, the impedence taken through the soles of my feet. Out of interest I have been measuring my b.f% using this both first thing in the morning after morning piss, evening prior to meal, and just before going to bed.

The results vary wildly morning to evening, although show some relative consitency morning to morning. The difference generally between morning and evening has been about 6% higher in the morning. I think this is probably due to lower hydration.

At my gym they have what appears to be the same hand-held BIA as the photo HASH posted. So, I have also been using this out of interest as well. This I have been taking at about 6:30am when I first get to the gym before doing anything, so is somewhat comparible to my morning foot impedence measurement. The %'s I have found to be approx. 10% lower. However, today I also checked after a back and bicep workout and the number was another 5% lower still.

So, according to these devices my b.f% varies from 10% to 27%. I believe I am in the 16-18% range at present.

I think if you use BIA at the same time everyday over an extended period without believing the actual % shown, you can see your relative change, but will see up to 2% variations day to day. But as far as any real indication of actual b.f% forget it.

Its calipers for me from now.

Hope this helps.
IPR

tangun · 05-14-2002, 09:50 AM

IPR,
I know of no better way and trust you me, I've been around the block many times on BF analysis. A good guy can tell you your bodyfat within .5-1% very consistently with calipers. They have to be good calipers though I must stress that point.

labouche · 05-14-2002, 10:08 AM

we used BIA in my college classes and were taught that hydrostatic weighing and the skinfold method were, at that time, definitely more accurate.
its based on the electrical conduction of fluids and the fact that fat-free mass contains more water and electrolytes. age and gender are also considerations taken into account as far as the prediction equations r concerned.

there r 5 definite guidelines:
1. no eating/drinking within 4hrs of test
2. no exercise within 12hrs of test
3. urinate within 30min of test
4. no alcohol consumption within 48hrs of test
5. no diuretics within 7days of test

if proper protocol and equations r used BIA will yield standard errors of estimate for %bf within +/- 3-4%.

* info taken from Heyward, 1991.

tangun · 05-14-2002, 10:18 AM

Labouche,
exactly, that's what's so inaccurate about it. Not only do you have all those factors that can really skew results, but 3-4% accuracy as it is, that's pretty poor in my opinion. Also, most of the commercially available gadgets are just really poor quality compared to the grade A expensive stuff used in human performance labs, etc.

IPR · 05-14-2002, 07:28 PM

Wow, I knew they were inaccurate, but +/- 3-4% could mean a reading of 8% or 16% for someone, very misleading. Damn, I think looking in the mirror is more accurate than this.

Out of interest, as my morning foot and handheld BIA's seem to give reasonably consitent results, I am wondering if I can calibrate the difference from my real b.f using calipers occasionally. Maybe HASH can consider doing this as it will give more realism to his BIA reading (and not have to throw away what he just bought) and only occasionally need to get a professional caliper reading.

Just an idea.

IPR

tangun · 05-14-2002, 07:42 PM

the two best indicators are pictures in controlled lighting conditions + calipers. My humble opinion. Find a room in your house, shut all the windows, turn on the lamps, and take shots front and back. Replicate those exact pictures, including what time of day you take them (even if you shut the windows, to be extra accurate), over time. That combined with bodyfat calipers (quality ones) by a well-trained person is about as accurate as you can get.

HASH · 05-15-2002, 03:23 PM

Thx guys for the help,

After over a week of using this ph*kin' BIA thing, I realized it's underestimating my bf% levels, but actually don't know by how much. I'm using it first thing in the morning in consideration of 'labouche' conditions, and seems to be consistent (although it varies by 1% sometimes...)

I can assure u it's not the best to use, but actually got tricked when i thought it would be pretty accurate in consistensy at least... I KNOW THE READING IS NOT PRECISE, but thought it would be accurate in tracking progress!