Complete wak.
Complete guess output from an operator that hasn't a clue using an instrument that doesn't work as it claims.

I use one of the Tanita scales where you weigh barefooted and it sends the very mild current through your body. While results vary from day to day, if you weigh and do % fat at same time each day, and average across a week, I think it is fairly accurate at least for tracking an individual's relative % fat. Acc to the users' manual, your most accurate % fat readings are in the evening after you've been up all day, so that is when i take my readings, well-hydrated but on empty stomach so weight is accurate. The most interesting thing I've noticed is that when i lose weight, it is about half fat and half muscle. For example, 180 lb and 10% fat, I am 162 lb lean and 18 lb fat. At 160 lb, I am 5% fat or 152 lb lean and 8 lb fat. Thus I lost 10 lb lean mass and 10 lb fat, which explains why I look much more muscular at 180 vs at 160; I'm about 6'1.5" so at 160 I'm quite skinny. I've been as low as 150 for several yrs but I did not have the Tanita scale at that time so no data.

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"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."

I also have a Tanita that I've been using for over ten years. It's Ok for long term tracking. I weigh myself almost every day. When I'm actually paying attention to the details and trying to lose weight or fat I'll average the body fat and weight for a week and only track my weekly averages. If your a numbers geek it's close enough to keep you interested and motivated in your efforts but I wouldn't call it accurate. If you're only having it done once a week or once a month I wouldn't bother because it fluctuates too much with your hydration levels.

Unlike ericmulk I weigh myself in the mornings when getting out of bed. Not saying this is better, it just provides me with a consistent time to do it. I'm dehydrated from sleeping and my stomach is empty. Yes it shows a higher body fat but I'm tracking a trend, not absolute accuracy.

Some people will get their panties all in a bunch over the Bio-impedance method claiming that you're a idiot for using it because it's not near accurate. While they are right about it not being accurate I did a bunch of reading on all the different methods awhile ago and short of having an extensive autopsy none of the methods can be proven to be extremely accurate.

Actually, just for the record, I also weigh in the mornings and use that weight as my weight for the day in my log book. Then I weigh again in the evening and use the % fat as my % fat for the day. In the evening, my weight will usually be 1-1.5 lb higher and the % fat 3-4% lower.

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"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."

Hello georged and All,


I use the Tanita scale to weigh ...... and when I want to feel good about what it shows ..... I wet my feet and get a lower fat reading .......probably better contact with the scale.

It sends a current through the legs and measures the change ... and shows about 6 to 8% fat .... but appears to be measuring only the lower body.

There is another device that you hold with your hands and sends a current through your arms ... it measures 20 to 30% fat ... again considering the circuit ... upper body by arms.

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Cheers, Neal

+1 mph Faster

This was a hands and feet (ie. full body) unit. Lower body units only measure your legs...

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'It never gets easier, you just get crazier.'

The GE Inbody is a pretty good device with acceptable accuracy but it costs $18K. Not sure what model you used but if it was the GE Inbody, and you followed the directions, you got an OK estimate.

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Simplify, Train, Live

Pretty much complete garbage. DEXA is the gold standard and well worth the $175 or whatever it costs.

Did it look like this?

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DFL > DNF > DNS

Yes.

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'It never gets easier, you just get crazier.'

In order to get best results, one must go at least 3 hours without water, food, or exercise prior to use. Hopefully, you got a print-out that contains information on your bone mass, muscle, fat, and intra/extracellular water content. We have both DEXA and multiple InBody devices at my workplace. They are similar in results when used properly.

As already stated, at $15,000-22,000, this is not your $100 Tanita home unit ;-)

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DFL > DNF > DNS

But doesn't the DEXA count your brain as a lipid, hence considerably over-estimating your % fat???

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"Anyone can be who they want to be IF they have the HUNGER and the DRIVE."

A couple of notes:

1. As has been mentioned, not all BIA devices are created equal. Multifrequency BIA devices (such as those produced by Inbody) use multiple frequencies of current to estimate body composition, and do tend to produce values that are more similar to those produced by DEXA. There are a fair number of studies that validate multifrequency BIA against DEXA, with multifrequency BIA (on average, across studies) underestimating BIA against DEXA by 2-3%.

2. Multifrequency BIA body composition estimates tend to be highly reproducible (they show excellent test-retest reliability) as long as several assumptions are met. As has been mentioned, it is important not to eat or exercise for 2-3 hours before the test. Moreover, a test participant must be standing for at least 10 minutes (preferably 20) before the test to allow fluid to settle in the lower extremity in a reproducible fashion (body fat estimates can increase up to 3% over a 20 minute period from sitting to standing). Finally, arm position when using an Inbody matters (I have experience with the 770 model) - participants can "gain" up to 3% body fat when moving the arm from a fully adducted position to a position of 90 degrees of abduction. This final point is generally not reported in the validation literature, which I think is a real limitation based on our own lab observations and pilot data. We use a position of 30 degrees of arm abduction, which is similar to the only reported value I could find the published literature. For the best (most precise) results, I encourage individuals be assessed at the same time of day under the same conditions during each test.

3. It is important to remember that DEXA, like BIA or underwater weighing, arrives at a body fat "value" through an estimation equation. DEXA does not measure body fat, and I don't believe studies been conducted to validate DEXA using actual human cadaver data. DEXA has been validated against animal cadavers, and I encourage the reading of these studies if one has an interest in the validity of DEXA values.

An older, although informative, analysis of body composition methodology was published by Ellis in 2000 and is freely accessible via the Journal of Applied Physiology link at PubMed (https://www.ncbi.nlm.nih.gov/pubmed/10747204). A newer, updated review may include much of the information on multifrequency BIA, as much of the validation information specific to this methodology has been published in the past 5 years.

Thanks for a very interesting article.

In your estimation, how much would cycling 10km at a light pace (how I got to the appointment) affect the results? Am I right in assuming for optimum reproducibility I should cycle to the next test in a month or so?

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'It never gets easier, you just get crazier.'

Impedance devices can be okay for measuring changes over time, but aren't very accurate for determining actual body composition. In my studio use an Omron scale that has a handle for a quick weekly check on clients whose goals include body composition. For more accurate numbers, we use an infrared body composition analyzer that cost about $4,000. We've found it to provide numbers relatively consistent with the other more expensive equipment and methods, such as the $15k-$20k devices and scans/water weighing, at a fraction of the cost and with less inconvenience to the clients.

The biggest problem with impedance devices is that they all make assumptions based on age and gender. They are especially inaccurate for anyone over about 35-40 years old who is fit. They will give a higher % of body fat than actual for them. Keeping all other parameters the same, they will indicate a BF% 3%-4% lower for those older fit individuals when you lie to it by entering an age 10 years younger than the person really is. If they're used in a consistent manner (same time of day, similar hydration levels, etc) their consistency is pretty good even if their accuracy isn't. It's important to understand both the value and limitations of the tool being used.

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Don Larkin
Reach For More
http://www.reachformore.fit/
USAT Lvl1 Coach, NSCA-CPT, NASM-CPT, BS Exercise Science