T Nation

Body Fat Monitors

Has anyone tried the electronic body fat monitors. I was thinking of buying either the Tanita Bodyfat Scale or the Omron Body Fat Analyzer. Anybody tried either of these products?

I have the omron, it is grossly innacurate.

When do you use it Iron babe? I’ve found it to be reasonably accurate +/- about .5% if you use it in the morning right after you drain your bladder. I weigh myself at the same time. Forget using it any other time or you’ll get all kinds of interesting readings.

The Tanita has a basic accuracy of +/- 5% Bodyfat and a repeatability of 1%. Now this accuracy is plus or minus (+/-) 5%BF not 5% of the indicated value. This is likely a best case, lab calibration. That means using calibrated weights and resistors in an environmentally controlled room. This accuracy given is also the deviation from the exray method of bodyfat analysis. The most accurate being autopsy. They state it is better to test yourself at about 5-6pm each time rather then upon rising in the morning due to dehydration.
Being dehydrated will change body weight and resistivity.


So… what errors are involved when using this type of gauge at home?? … here are a few… temperature(most electronic labs are around 23 degC) there could be a small correction factor if this differs substantially, humidity(not likely a concern if it is under 60%RH). Are the pads clean? Do your Spiderman PJs have the built in feet? this will add to the impedance measurement. Um what else… there are several sources of induced error to look at to determine exactly how accurate this instrument is. Total accuracy is calculated by squaring each error then adding them all together and taking the square root ie… for basic accuracy 5% & the repeatability 1% it would be 5x5 + 1x1 then take the root of that sum… did you get +/-5.099% BF ? Now we don’t know where they got their figure for basic accuracy… accuracies are seldom stated with confidence level or what is known as sigma… a one sigma means about 68% of the measurements taken will fall within the 5% BF range… a 2 sigma confidence level means about 95% of measurements taken will fall within +/- 5% BF of actual… a 3 Sigma is within 99.8% (ever hear that nothing is 100% certain?) confidence of within 5%BF … most Labs use a 2 Sigma confidence… not sure what is used here. This is only skimming the surface of accuracy and what it really means…

Don’t worry too much about accuracy…skin calipers, hydrostatic weighing, BIA even DXA are all estimates and will not be 100% accurate (only autopsy is 100% accurate).

What’s important in terms of body composition is that you find something that can measure changes in body fat (rather than absolute amount of body fat). I’ve found Tanita pretty good as long as consistent hydration protocols are followed…just don’t get into the trap of trying to measure yourself everyday it really screws with your head

I agree with dngu - or is it dgnu - I don’t know, I forgot it when I pulled up the answer machine.
Anyway - I have a Tanita and I swear by it for one reason - it gives me SOMETHING to compare with. Remember this - whether you’re showing 7% or 18% BF, if it’s moving in the direction you want - YOU’RE SUCCEEDING! Now, as far as the Tanita readings - I’ve compared them with Accu-Measure calipers and the FatTrack digital calipers, and the Tanita measurements are about 2% higher than both of those (and both calipers come in real close to each other). The Tanita is a “no-mind”, simple way to get a good quick reading. I use it every morning (although, what was said about using it everyday is correct - it DOES spin your head around!). I think the Tanita is worth it - as long as you keep in mind what I said earlier - just move in the right direction (and by the way - BE CERTAIN TO SET IT FOR THE ATHLETE. I was using the “normal” setting because everyone kept saying the other was for Aerobic training - but it was registering 10-11% higher than my actual bodyfat! Talk about screwing up your diet…)

Yes it can be used as a rough gauge, and yes I was being a little anal with the explanation I gave, but it is good to understand what you are buying and what expectations you should have. I’m just used to measuring in parts per million (ppm) or better and this is somewhat sloppy. These gauges do require calibration occasionally. You would likely need a set of calipers or get tested and then ballpark yourself with the scale… I’m not saying they are bad or good… just that the indicated value is not exacting.
If you have the money and want more 411 than a mirror can give then fill your boots… just take them off before stepping on the scale. Uh… and Ironbabe! wondering if your boots are the thigh high type, Just messin…

I sell both. The tanita scale is the better of the two, but i have found calipers to be more accurate. the scale works mostly on hydration levels. it is a quick and easy method, but the results don’t always make sense. One time it told me i was at 12% bosyfat when i had no cuts in my quads, and it currently tells me that i am a 14%, when i have cuts in my quads now, and striations in every bodypart. so save your money and buy a set of calipers

My omron doesn’t have a setting for athlete. Maybe that’s the issue.

When I said accurate, I actually meant “repeatable”. When I weigh in the morning and use the ol’ Omron, I come out with consistent day to day measurements. It doesn’t go up and down like a yo-yo unlike measurements that I’ve taken at other times of the day. I’ve seen a two percent difference before and after workouts so it didn’t make sense to use it at six since that’s when I’m leaving the gym. I’m with you guys though. As long as it’s moving in the right direction then the actual numbers don’t mean a whole lot to me.

I had Tanita fax me a couple of service manuals… some models do not have an athlete mode. And the ones that do have a disclaimer that it’s not meant for BB.

Dale…providing useless info since 6:55am

This is good, because it comes up AT LEAST twice per month! As I’ve stated before, I have both the Tanita 612 and the Omron Body Fat Analyzer. (The Omron does not do weights; you have to plug a weight in). THEY ARE TOOLS! I agree with Mike and dngu047. I use them to measure the RELATIVE progress I am making, and for that, they are great. Using them both also gives me sort of a “double check” on relative progress. I measure ONCE PER WEEK, and try to do it at rougly the same time. THEN based on what they say AND WHAT I SEE IN THE MIRROR, I adjust.

I dont recommed such devices that are based on bioelectric impedance. Last year I worked with a group of engineers to try to develop an “accurate and reliable” device that people could use at home. We used Bod Pod, Skinfold, and BIA (bioelectric impendance) data to try to develop this new machine. I dropped out of the project because it looked like they were going forward with development althought the data were not as good as I would have liked.

What was the problem? Well, BIA measures are determined by body fluid content which is assumed to be proportional to total lean body mass. Now, for people of average bodyfat content (20-30% or so) who dont change weight often and are usually normally hydrated, this method works OK (not great, but ok).

But for someone who works out, fluid changes 2 ways. First the proportion of lean body mass that is water changes with a muscular body vs a "normal" body. Therefore the very assumption that the thing is based on is categorically wrong in muscular individuals. In addition, when either eating high cals or low cals, basal hydration status changes and therefore as soon as you try to change your body composition, the basic assumptions are again violated. So it's useless for muscular individuals and for dieting or overfeeding. So if you're a normal person this is a good tool. But if you read this forum, these tools probably are useless for you.

Even the Bod Pod is useless in lean + muscular individuals. From lab data, the Bod Pod works in normal people but as soon as you put me and my buddies in, it's a joke. Here is an example. Each and every time I diet, I drop a lot of fat pretty quickly. However, the BIA and Bod Pod actually read me as FATTER! The BIA usually reads me at -5% fat but as soon as I start to diet, I turn out to be +5% fat. In addition the Bod Pod usually reads me at 8% but as soon as I start to diet, it reads me at 12-14% (at this point I have cross striated quads, tris, full abdominal/serratus/intercostal visibility, and even some visible striations in my glutes).

The very best method to monitor body comp changes is to buy a skinfold caliper and measure the following sites...chest, biceps, triceps, suprailiac, subscapular, abdominal, midaxillary, thigh, calf. Then just record your readings and watch how they change. This not only tells you if you are losing fat (the sum total of the measurements) but where it's coming from. There are lots of web sites out there with pics and descriptions of how to do this. Now, it wont give you your % fat but so what. You know if you're fat or lean. You really need to know if you are changing.

Guys, I have the Fattrack caliper device. Unfortunately it’s only measures 3 sites, but could it still be useful in tracking progress? This is the most important thing anyway, right? Or, could I use it on the sites that Mr. Berardi recommends? This way I would have to forget about actual bf % and just focus on the skinfold readings themselves. I just bought it a few weeks ago, which is why I’m asking all these questions. For anybody who uses the fattrack successfully, any help would be greatly appreciated.