T Nation

Bodyfat Scales

Guys,

Looking at purchasing a device to measure bodyfat and I’m down to either of (1) Tanita Bodyfat Scale or (2) FatTrack Digital Body Fat Caliper.

Both have been reviewed in ‘Stuff We Like’ but it’s not conclusive as to which is best.

Anyone have experience with either product? Good or bad?

T: This question ALWAYS leads to heated debate, (which makes it a good question to have on “The Forum” every once and a while!). I use two devices (a sort of “double check”); the Tanita 612 and the Omron Body Fat Analyzer. I USE THEM TO MONITOR RELATIVE PROGRESS! You will get a lot of HEATED discussion, because there are a LOT of people hung up on ABSOLUTE bodyfat percentage numbers. You would think that because a device was giving them a certain bodyfat reading that it was making some digital commentary on their dick size!The reality is this: anything short of autopsy and some VERY expensive nuclear studies will have limitations…(and even bodyfat measurement with AUTOPSY has some limitations). I am pleased with both products…just my take…

I’ve got a Tanita model 612. It is supposed to be the best but it actually sucks.

I have a Tanita BF scale and found it to be very inaccurate and a complete waste of money. It said my BF was more than2x the amount measured with calipers.

My thoughts exactly mate, I only want to measure my progress and don’t feel the need to know my ‘exact’ bodyfat percentage.

How do you rate the Tanita?

How exzpensive are these things anyway?

T-Rex: Yes, this does always generate alot of heated argument… all of them do suck in terms of getting an absolute measurement… I’ve been dunked, pinched and electrocuted (bioimpedence) to measure body fat, and they were all within 1% of eachother (on the same day, within a few hours of eachother)… that scale always had me 4-5% higher. So, the absolute measurement from them to me is crap.

So, if your going to use it for relative trends, just make sure that you always measure it the same way, at the same time of day (right after your morning piss and possibly a shower is a good time I hear). These things are very susceptible to what you ate the night before, how hydrated you are, etc. I think your best bet for an absolute measurement is really to find a qualified person to measure your BF with calipers from many sites (9-12).

Steve

I have the Fatrack digital calipers… I can’t really comment on if they are accurate or not, but its easier to “calculate” your BF from these as they do it for you as opposed to the regular old plastic calipers which you have to do math with. Plus it stores your readings for reference, etc. At like $39 or so, its much cheaper than the Tanita scales. Actually, I used to have two different Tanita BF scales, and they sucked (I returned them for a refund). I think skinfold measurements are the way to go (if you can’t have the water-immersion method done)… In anycase, I have been using the FatTrak calipers consistently for three weeks now while on the Fat Fast diet, and what I do is take five seperate readings (not measurements, but five complete readings) and then average them out. Generally, each time I take my BF at one session, each reading is different but thats just due i guess to my crappy pinching technique. I dont know, even averaging this out my BF has been dropping from week to week so it is definitley registering a difference.

I have the Tanita & is worth every dollar. Great investment.

I have commented at length on these scales before. I’m a metrologist (the science of measurement)and deal with test equipment and measurement uncertanties. I am not stating good or bad… just what to expect as far as what these read and how well.

The manufacturer of Tanita states that the measurements are within +/- (plus or minus) 5% Bodyfat (BF) (2 to 3% for newer models) of the Dexa(Dual Energy X-ray Absorptiometry) method of determining BF. How accurate is the DEXA method?..as an example…If the DEXA method is within +/- 2% BF of the “TRUE” BF then the Tanita would be within 5% bf of that or +/- 7% BF (4 to 5% BF for newer models)It would actually be slightly better but I won’t even begin to explain why. The athlete mode is not meant for professional athletes or body builders (stated by the manufacturer).

Ok... so what you see is not necessarily your TRUE BF level, some use it as a guide to watch trends gaining or losing weight. This is feasable, the repeatability is stated as +/-1% BF (in other words...it may measure 5%bf over your true BF, but it will repeat those measurements to within 1%BF.That repeatability is actually pretty good) you should use it at the same time every day... morning is not the best time as you are likely to be somewhat dehydrated (again this is mentioned by the manufacturer). Make sure that the contacts and your feet are clean if it is a stand on scale.

These types of instruments calculate BF from the values of your weight and the impedance (resistance to current flow) of your body…
the calculation co-efficients are fixed for each mode(some have child, adult and athlete modes)… other than not being meant for bodybuilders no measurement errors would likely be induced by these co-efficients

One area where errors could occur would be in the weighing portion of the scale… I calibrate scales from 50.00000 gram to 15000 kg frequently, and they do need adjustment from time to time… if it doesn’t weigh correctly then it can’t calculate a proper value… Differing hydration levels likewise induce calculated errors…

I by no means intend to discourage anyone from purchasing any bio-impedance type of gauge, and I surely don’t want to start a heated debate… I just wanted to give you a heads up on what to expect as far as measurement uncertainty, accuracy and reliability… it’s what I do!

Dale; thank you VERY much for your analysis! If I read correctly your findings, then what I’m using the Tanita for is very valid; following the TREND of fat loss. Although it may be 4-5% off from my “true” bodyfat%, it’s repeatability of those measurements is +/- 1%. When I factor in 1) Cost 2) Convienence of use and 2) The fact that it does a total bodyweight for me also (which calipers can’t), the Tanita meets my needs. T-Rex: With that fact in mind, I would rate it excellent, with a company that is continuously making improvements and innovations…QUESTION: Does anybody have stats on the accuracy of calipers relative to “true” bodyfat%? What about if the person is very obese? OR if the person is “fat-thin” with a lot of loose skin?

Repeatability is stated as +/- 1% BF, so yes it could be used to track trends in fat loss or gain. That said, it is important to do everything possible to get repeatable readings.

Retesting the same time every time, same hydration levels, clean feet and contacts, yada… yada… yada.

It may also be wise to occasionally check to see if the scale is weighing correctly. Either weigh yourself on a known accurate scale then compare readings with yours, or use weights with a known value to test the scale.

Tanita does have calibration procedures for alot of models, but understood from talking with their tech support that they don't normally recalibrate homeowner models ... the cost is likely as much or more than a new scale...something to check on... calibrating these requires having accurate weights and certain resistors on hand... resistors come in different tolerances so if anyone wants to calibrate at home, get the most accurate. The techs were very helpful in sending me cal procedures for a couple of models.

I read a website awhile back that gave accuracies for the different methods of BF analysis. Unfortunately I don’t recall exact figures for some reason either +/- 5 or 7% BF comes to mind for calipers, I don’t recall that the number of sites tested was quoted. I also don’t recall the url, but the info is out there, and those figures should be confirmed.

(Afraid I’m only anal about committing certain things to memory … hope some of that helped)

one last thing… I would recommend not keeping this item in a humid bathroom.