BIA - Bioelectrical Impedance Analysis

I guess I'll see. It might be possible that you are 7.6% and got genetically unlucky such that it is all in the stomachal region. Also possible you just have your version of cat pouch?

Maybe you should just get DXA and settle this once and for all...

OT humor re: AIDS boy. We were practicing ball last night and I guess to him I was hitting well. So my wonderful friend asked if I was juicing. I said "I thought I was AIDS boy?" ... he said "well, ya, but not when you pick up a stick, then you're juicing".

He's going to give me an identity crisis.

On topic, 7.6% seems unlikely. I still have a little pooch around my belly. I guess next week are my "after" P90X pictures, so maybe I'll post a before/after and you can tell me if I look like 7.6%. I can assure you, I ain't :)

Why couldn't you be 7.6%? AIDS boy! *grin*

Yes, the general stability of the handheld readings is what leads me to trust it more than the scale. And it does move opposite the scale on occasion, but especially when there is a big move on the scale numbers.

All I can say is 'wow'. My scale is all over the map these days. I went up 2% in 4 days and 1.2% last night. Meanwhile, the handheld is just ho-humming along between 7.2 and 7.8. While my scale went up 1.2% in a day, the handheld went down 0.2% over the same period. LOL! In fact, I would say that far more likely than not, the two move in separate directions on any given day.

The problem with the handheld is that I don't think I'm 7.6% body fat, but the stability of the reads seems a lot more probable. I currently put no stock in any of these numbers at the present, but I'll keep recording them for now.

I see that a lot, BB, that the handheld moves opposite the scale. On my stuff, the handheld's swings are much smaller than the scale though overall too. I think the handheld is much less "fooled" by hydration than my scale was, or possibly has some sort of "adjustment". That is all I can figure by its swings in reverse of the scale. So I know hydration affects it some but it appears to be not nearly as much. That's one reason I think the handheld is the best BIA device I've used.

I do suspect, as someone said recently, that the Omron scale with both footpads and handgrips would be the most accurate device. However, by the same token I believe that the capability of inputting smoothed weight into the handheld is a significant advantage in getting better (smoother) numbers out of it. Really the best scenario would be to have a scale with the handgrips that remembered enough days back to do a smoothing calculation on the weight and use that as an input to its BF algorithm (and then ideally to smooth that as well). Having that would prevent a lot of this "OMG ditch your scale" and "stop weighing in fractions" BS that I see bandied about here.

Then again, it'd help if I were to prevent myself from getting pissed off at those people and inevitably posting about how truly wrong they are. Heh.

Weight fluctuates every day. I think today it went up. I guess I gained all fat yesterday during all of that cardio. LOL!

Must have gained fat on the arse and lost it in the chest :) was your weight the same or did it increase as well.

OK, so I got the hand held Omron device. Here is where things get a little interesting. My scale this morning went up (from 16.5% to 16.8%) and my handheld went DOWN from 7.2% to 7.0%. LOL! Yes, I did them both one right after the other first thing this morning (after handling urgent business).

I'm going to continue using both devices each morning and tracking the numbers to see if I can discern any pattern. My numbers with the hand held are getting a bit steadier so I can probably attribute the wild variations on day 1 to PEBKAC errors.

Nope Tuesday was not a typo. I was trying to get to 12% before I started going back up but I didn't want to do it all in one day :) Unless I have been magically unable to change either body fat or muscle growth in the last 6 months, my scale uses nothing but a calculation.
Any way, since I "hit" my goal I think it's time to start eating again :) Does it count that it was only for an hour or so? Heh.

No, I appreciate you relaying the experience around the answer, because I can relate. This is the kind of measurements I'm seeing as well. I guess if this is "normal" (and you suspect it is not), I can accept it. But I don't think it's normal either and the reason for that is that I can get shifts of 1% or more within second of each other.

By the way, I hope Tuesday's weight was a typo.

There are a couple of things that seem to affect measurement that I've noticed.

1) extremely straight knees. Any bend whatsoever seems to result in a lower reading. So I keep my knees super straight.

2) Having any portion of my foot off of the metal. This one is harder to get right at 5am.

When I get those two right, it's marginally better. But I'm actually considering ditching the readings or at least severely diminishing their value in my life.

The accu measure caliper GL recommended works well for me, although you can't get the pretty decimals like the scale it seems to be fairly accurate. It works well for me because the one place I still carry a visible amount of fat happens to be the place you measure with it. I'm also not so sure daily bf % are very relevant, I'm pretty convinced that total body fat does not change that much in a days time no matter what the weight fluctuations are. Is it really relevant for instance when your weight jumps 5 lbs due to water or whatever that the percentage of fat is now different? Did you really gain fat, or even lose fat?
Take the last couple of days measurements for me as an example.
Monday 159.2 lbs 13.3 % bf 21.17 lbs fat
Tuesday 155.1 lbs 12.4% bf 19.23 lbs fat
Wed 160.4 lbs 13.7% bf 21.97 lbs fat
Monday was an extremely hard work day in the sun all day digging and sweating. Did I lose 2 lbs of fat and gain it back in a day? Doubt it. So hydration affects even caliper measurements and renders the results inaccurate, therefore irrelevant.

So, my answer to your question is no. :) would have been simpler to just say that huh? :)

My scale is back to being all over the map. I had wild variations in readings this morning and really over the past 3 days (over 1% differences). It's one thing to not like the reading you're getting (i.e. you ate right, exercised all week yet your weight went UP), it's quite another thing to not feel confident in the reading you're getting.

I keep leaning more and more towards my wing man (Dan) opinions of ditching the scale or maybe using it as a rule of thumb instead of basing my FFM gains/losses on this thing week after week.

So this was probably a roundabout way of asking, is there a superior way to measure BF% on a daily basis?

Yes, part of the variance of the Tanita is that it is using daily weights as inputs into the statistical models. Since the Omron is using roughly the moving average weight, it's naturally going to be more stable. I'm honestly not too concerned about why, more about what gives me a reasonably accurate view of what's going on. When I look at the graphs, while the Tanita looks like it is sneaking up (which is what PD's fits have it doing), the Omron results look like they are sneaking slightly down. That sounds more accurate to me... and the small changes in BF% that it reads would make a lot more sense. I don't have consistent enough caliper readings to have a feel for whether I think my BF is sneaking down (but will have that in a couple months). However since I occasionally notice more definition on me I can't believe that my BF has been sneaking up. Exactly why I need to start calipering regularly and also using the myotape for confirmation.

I don't think the Tanita is "accommodating" different hydration levels. I think it just reads different hydration levels using similar statistical models as it uses for BF. I think the thing takes gender, height, activity level, weight, and the BIA value (and I haven't read that greek-letter paper but from the discussion I gather it is using only the resistance portion and not measuring reactance) and just sticks them into formulas or lookup tables to get all the numbers it spits out. I don't think there is any accommodation for anything. Basically I only ever look at the BF% because I think (a) the other numbers are bunk and (b) they are trying to pull too much information out of too little data.

Yuck, yuck. We'll converge at some point on the FFM, if you're lucky.

Do you suppose the Omron is more consistent because the input is more consistent? Doesn't the Tanita try and accommodate weight and hydration level in real time? Where the Omron has the same inputs each time until you change it.

I'm not going back to compare them since I've been monitoring, but I created a Goog spreadsheet to compare results from two settings on the Tanita and the Omron handheld unit that I have. So far it's looking like I should switch to the Omron for BF measurement. I may just do that, and go back and change my PD numbers. I'm not going to go back to change any numbers on Spark though - I'd just want to get PD off to a quick start so that my running averages wouldn't be screwed up.

spreadsheets.google.com/ccc?k
ey=0AkSv2
sLySHBYdGZ1X1BnZ1RSNUdxdzRYbF
ZHUTZ
SbUE&hl=en

I'm going to caliper roughly the first Sunday of every month to confirm how I'm doing (my caliperer reports that the Slim Guide calipers are extremely easy to use). I'm interested to do a circumference measurement method monthly too but I haven't looked into those much yet. Since I have the Myotape they should be pretty easy though. I do question whether they would work well for someone with relatively more muscle mass (I have more lean mass than Bill has total mass... *snicker*).

I also may eventually rely mosty on pictures. It'll be picture time for me again in 2-3 weeks when I finish P90X.


Edited by: GRACEFULIFE at: 7/18/2010 (12:52)

I use a handheld BIA device and use a circumference method to measure my body fat percentage. I find that they dont track together. Like Grace, I have decided to use BIA more often because it is more convenient. I have not use the high-tech tracking that Brew uses hehe. I found an equation that corrects for ethnicity for the second method.

I have noticed that when the two methods track together I also see the change visually by looking at the mirror.

because you're more dehydrated first thing in the morning after 8 hours of sleep then you after a full day of drinking water.

So why is it again that my BF% first thing in the morning always shows much higher than when I check at night?

MRPLATSON, if you are 17% or lower then you count as an athlete as far as body fat percentage goes. Also, it's related more to how long and how often you work out. According to my scale's manual, it's mostly to compensate for the fact that people who work out a lot tend to be more dehydrated than others.

I don't recall if you were involved earlier, but if you look at my and 4A's graphs you will see that we realized the scale mode needed to be changed when our BF trend stopped going down and just stayed the same. Hers was considerably more marked than mine.


Edited by: GRACEFULIFE at: 7/1/2010 (17:22)

Check for the athlete mode, mine doesn't have it.

I've been putting off changing the 'mode' on my scale (assuming it has athlete mode). For the last month my weight has steadily gone down but my BF has remained stationary in the high 17's and I just can't buy that.

It's such a weird thing for me to think, that's after only 3 months I'm some sort of 'athlete'.

Interesting. I did three reads (not 30! heh) on my scale this morning and got 14.4, 14.4 and 15.3. I may continue to do 3 reads per morning to see if I can discern a trend. One thing I noticed about my 15.3 read is that a larger than usual portion of my left foot was not in contact with the metal.

This weekend I may do 30 reads and see how wildly it varies. Might be time for me to get a scale like yours.

Edited by: BREWMASTERBILL at: 7/1/2010 (06:10)

spreadsheets.google.com/ccc?key=0AkS
v2
sLySHBYdF8tN09SbWZVTzVzSUFYTEJVa0Z3ZR>Gc&hl=en

My scale and BIA devices are very repeatable. I'm not even going to do any statistics, because I think the numbers speak for themselves pretty well.

Bill, maybe you gained brain, or bone. Plenty of other choices. Tapeworm?

I could reasonably easily do the single-point measurement with the accu-measure myself. However, I don't think that's exceptionally accurate for body fat percentage so I chug on with the scale. I should probably consider doing it though, because certainly as I've lost weight over the last couple weeks my belly is noticeably smaller.

My current plan is to do a double-check with the Slim Guide calipers perhaps once a month. It also seems likely that I'm going to switch to the Omron handheld.

GF just ordered an Omron scale that has a cabled handgrip also, so it can BIA the entire body. THAT will be interesting to play with.

I'm going to go step on my scale three times in both modes and record the results into that spreadsheet to get an idea of repeatability, also do the Omron handheld. Show me the data!

Well, I guess I can only say that I've gained 8 pounds from my low weight of 152 and my pants still fit the same and I'm on the same belt loop. So based on those very imprecise measurements, I'm going to say that I'm probably gaining muscle. (shrug).

@Dan

Compared with my weight (which fluctuated 8.8 lbs last week from Tuesday to Tuesday) yours is ridiculously stable! LOL

Take a look at my PD graph sometime. It's all over the place!

The accu-measure is very easy to use. The problem with them is you are only checking one point and can only measure to the closest mm. I have been using the POS just for the decimal values short of a scan of some kind, that's likely going to be as close as I'm going to get to a true number. Apparently the older you get the thicker your skin is as the chart that comes with it shows that last year at these measurements I would be at 12.6% instead of the 13.7% this year :)

Hrm. I can't get the same value stepping on my scale twice. The weight will be the same, but the BF% will change a bit.

So what's the deal with calipers? Are they just a PITA to use? You guys all have 'em yet still use the electronic devices.

My numbers are not all that consistent, I started trying to gain on 5/16, hit an all time low of 156 2 days later, hit 164 after the various experiments we did and started a cut last week to shed some of the gunk after playing around. It took 4 days to drop back to 159 where I started, I will prob cut for another week and start the process over in earnest. During this period a caliper check every morning at the same time a weigh in took place and measured a very consistent 7mm with the accu-measure.
During this time my scale never read a body fat percentage change that was different at the same weight so its obviously just using a calculated value. Like I said before, mine might just be a POS.

Note: I haven't changed the weight I programmed into the Omron handheld. I'll probably change it when my moving average hits weights that are multiples of 5. When I show the readings, I'll note what the weight was set to on the device.

With any luck I can get some caliper play in tomorrow and not only get a double-check of my values but have an idea of whether or not the Slim Guide is any good (not anticipating Fat Track Pro to be worth a darn).

Edited by: GRACEFULIFE at: 6/30/2010 (00:33)

Gosh. My numbers are never that consistent. Amazing!

These are actual values, not averaged.

Hey Dan,

Are those values smoothed, or are your weights just that consistent?!

From my chart

5/16 159 13.3
5/21 159 13.3
6/26 159 13.3

5/23 160.4 13.7
5/29 160.4 13.7
6/04 160.4 13.7
6/11 160.4 13.7
6/25 160.2 13.7

When I got a DXA scan done in January, it said 19% BF.

At the time I was using couch potato mode on my Tanita scale and it said %BF was about 23-25%

I switched to "athlete mode" and suddenly %BF agreed with the DXA.

That was back when I weighed about 157 or so.

I was 161 this morning. My BMI is just on the cusp of dropping below 25 again. In about 4-5 more pounds if my %BF stabilizes again, I'm going to assume there's something weird about the calculations if you're using "athlete mode" and have a BMI over 25.

Always exactly the same? Like you get a 15% reading every single day? I don't get that, but it certainly hovers around the same values.

I still do not have any faith in bio0electrical impedance testing. For an example, if you were to look at my physics page, you can plainly see that if I weigh 159, my body fat (according to the scale) is always exactly the same. Maybe mine is a bigger POS than yours but I have lost the faith. :)

They usually provide trend. But I've read a couple places that they have problems at the fringes... perhaps at the low end (not sure if I even read that actually, maybe I'm fooling myself) but I've definitely read that they have problems on the high end and that they tend to classify anyone way overweight as 30% BF.

Also, 4A thinks that her current numbers are wonky and don't make sense, that she is at some unstable point in the maths. I think she is just having water balance issues but she says she drinks plenty.

24 June 2010 Tanita 22.5% PD avg 21.81 Omron 22.7%
25 June 2010 Tanita 23.5% PD avg 21.98 Omron 22.5%
27 June 2010 Tanita 19.0% PD avg 21.68 Omron 22.3%
28 June 2010 Tanita 20.3% PD avg 21.54 Omron 22.9%
29 June 2010 Tanita 22.2% PD avg 21.61 Omron 22.7%

Edited by: GRACEFULIFE at: 6/29/2010 (11:32)

So all of this has shaken my confidence a bit in these devices. Are we still in agreement that they do provide trend? The reason I ask is that I don't think my BF% has changed much since I bought the thing last winter. It's always reading in the 13's to the 15's.

Uh oh ... I smell a "secret". Get the cameras ready, let's get the infomercial going. Eat steak and gain muscle and LOSE FAT! It's the steak lover's diet.

That tip seemed to work for my Tanita. Obviously it could have been water balance or any number of things but I did notice that the morning after I ate a steak dinner my BF% dropped very low. It doesn't make that much sense, once I think about it, since 4oz isn't really a significant amount of added meat. Nonetheless, it seemed. to work.

Hmm,I have half a steak downstairs. I'm going down to eat!

"Oh, yeah, and it helps to eat a filet mignon the night before. It seems to think that's new lean mass."

I laughed, I cried...

It just so happens there's a Skwigg blog about fooling the Omron handheld body fat monitor.

skwigg.com/id52.html

I'm confused. Don't they use the same technology? Wouldn't they be thrown off by the same things?

I really hate bringing this up all the time but even though I like the simplicity of having a scale and BF reader in one I do question the accuracy of an instrument that can be flummoxed by the different between me having or not having gone to the bathroom prior to weighing.

And so, I imagine a hand-held monitor would be more accurate then a step-on model. I can't think of anything that would throw off the hand-held device.

I'm going to start posting my comparative results between my BC-533 Tanita body fat scale and the Omron HBF-306C, just for interest. I am using them both on athlete mode, but I have them set to 1/4" difference since the Omron has 1/4" graduations for height whereas Tanitas only have 1" if I remember correctly.

24 June 2010 Tanita 22.5% PD avg 21.81 Omron 22.7%
25 June 2010 Tanita 23.5% PD avg 21.98 Omron 22.5%
27 June 2010 Tanita 19.0% PD avg 21.68 Omron 22.3%

So far it looks like the Omron is much more stable than the Tanita. I have my suspicions that Omron may have more stable algorithms, but it could also be that it is due to this being a handheld rather than foot-read. Also it's entirely possible that newer Tanita models have a more stable algorithm as well. We'll see how things shape up in the future. I may start calculating running averages on the Omron data after I have ten data points or so. And if it is significantly better, I might just move to using the Omron as my PD data.

I also saw the friend and borrowed the FatTrack PRO and also scored the spring-closure calipers so hopefully I can get test those out some over the next few weeks to add my impressions to the caliper magnus opus.


Edited by: GRACEFULIFE at: 6/27/2010 (13:59)

Platson, you hit it on the head with your questions. These are one of the main questions I have about BIA, and weight loss in general. One day I began to wonder... when I lose weight, how much of that is really tissue and how much is water? Similarly when I gain weight?

One part of the answer is in the wiki article for adipose tissue en.wikipedia.org/wiki/Body_fa
t " It is technically composed of roughly only 80% fat" so that at least puts an upper bound of 20% on its water content. Strangely, later it says "Human fat tissue contains about 87% lipids" which would put it at no more than 13% water. Now obviously there should be some extracellular fluid which will be mostly water and I don't know if that is included in these estimates or not. Still, it seems like one could safely say that body fat is 10% water or less.

So no, you can't keep from putting on fat by drinking less water. *grin*

I have come to an point where I need a question answered and I can't find any resources that would do it for me...

The BIA measures my BF and my Water Content by some magic of electric thingamajiggy...
I know Muscle is about 70% water, that means for every pound of Muscle I gain .7 of that will be water and .3 will be 'tissue'.

So I come to the following questions:
1. What % of Fat is Water?
2. When the scale spits out the #; is part of the BF% water? is part of the WC% the water that's in the Fat?

Edited by: MRPLATSON at: 6/7/2010 (13:50)

OK, this might explain why my scale doesn't have "athlete mode". It allegedly figures out my bone density.

Athlete mode compensates for the fact that most people who are highly physically active tend to have much denser bone mass. So a person who is highly athletic would read high BF in non-athlete mode because the extra bone mass will impede the bioelectrical current just like fat (actually more so then fat).

My scale supposedly takes bone density into consideration. Although I think it merely solves that equation with missing pieces.

I don't think the BIA readings are complete garbage. It seems to vary from person to person in my house, but it doesn't seem entirely accurate. This morning, I stepped on the scale twice, one reading was 15.7% which I had never seen that high before. I stepped on it again and it read 14.2% which is a very low reading for me. So I did a third, which was 14.8%. Pretty much in the middle.

(shrug)

I'm not going to use it as an absolute measurement. But like weight, I'll monitor the trend using physicsdiet.com and hopefully get some usefulness in that fashion.

I'm. Just guessing that the scale has different algorithms to calculate the % body fat based on the measured resistance, depending on the expected amt of muscle or whatever. I'm technically overweight at 160+ so that probably screws up the model.

( my bones are 25% denser than average which also can throw off estimates etc)

OK, I still don't understand "athlete" mode. I don't have it on my scale, but is fat measured differently? Is there an athlete mode for weight? Help a publik skool graduate out here.

I had a DXA done in January and that's when I found out I should be using "athlete" mode. At that point "couch potato" mode was saying something like 27%, and DXA and "athlete" mode said 19%.

Right around 160 lbs the body fat percent measurement seems unstable. I'm guessing this has something to do with the way it's calculated by the scale.

At the moment it's bouncing around between 19% and 21%. I suspect when I get the weight back down below 160 it'll settle back down to around 19%.

I can do the same thing walking across the house and getting on a different scale. Magic 2 to 3 % fat loss. One of the studies said you need a different formula for different races, as we tend to be built differently. Yes Bill I think it's total bs and based on nothing but a formula. (And I apologize for urging you to get one:) )
Try this, Get a 5 lb weight and get on, see how much your percentage raises.
If someone can splain to me how you get electric feedback standing on a glass scale, I'll reconsider.

It all evens out eventually.

I can tell you that I was this weight 10 years ago weighting myself with a BF scale, I had a 2% BF difference and I can honestly tell you looking in the mirror it's visible.

So bring it down for us little guys, are you saying BIA is complete garbage and my scale is lying to me?

After reading some of the brain food posted up here, and from the 2 things I know about electricity,(I'm a plumber not an electrician),I think Bioelectrical impedance is a sales tool for the scale folks.

1. Electricity always follows the path of least resistance.
2. Electricity always runs downhill. Wait thats water, I guess I know 1 thing about electricity :)

I have even seen scales that claim to measure this with glass standing surfaces, yep, glass, non-conductive. Hey, I do know 2 tings about electricity :)

I can't hang, Billy. Hurts my brain to think.

Haha, good one Kricket. Actually, I worry that my body fat shows too low with the scale because my legs have leaned out much better than my stomach and moobs. I do have plans to fix that situation (both the lower-body-centric measurement and the moobs), but those plans may be more about obsession with tracking fitness indicators and gadget-freak-ness than actually what I really need to be healthier / leaner / higher performance. In reality I'd probably be better off with a few extra hours of cardio than the time I'll spend on that.

I'm also watching my bf trend this way. It's good enough for me. I do suppose, however, that my bf% would show quite lower if I were to get on this thing upside down. Probably not something that the guys need to be concerned about.

That part of my point that I forgot to write, Bill, is that scales without different modes are just unknown. Unfortunately in large part the the modes are unknown too - I've read that athlete mode corrects mostly for people who work out a lot tending to be less well hydrated than couch potatoes. But who knows how much of the mode action has been published vs. what is considered Tanita / Omron trade secret? This is part of why I want to dig into the details of it - maybe with sufficient pawing through the literature something will turn up.

So anyway who knows what of the four modes (or basically two useful modes) your scale corresponds to - or if it's right down the middle of the two for that matter. Although as mrplatson noted, it probably does not matter as much as us gadget freaks think.

Edited by: GRACEFULIFE at: 5/5/2010 (08:42)

depends on model, i guess

I don't have a mode that I can find. I broke out the manual and don't see any mention of couch potato vs. athlete. Is there any way to determine which mode mine might be or is it something in the middle?

"your scale isn't going to read BF as 30% when you're actually 10%, it's not going to read 10% if you're actually 30%"

That's probably true, though I'd guess it could have up to 10% error. My scale has three levels of activity for "regular person" mode and athlete mode. The three activity levels make perhaps .2-.4% difference in BF. The athlete mode gives a hugely different number, for example this morning's 17.5% on athlete mode was 26.2% on inactive regular person mode. However, they do both trend roughly correctly. I've recorded both numbers since late February (when I calipered in order to have some idea if switching mode was the right thing to do)... co-graphing them might be entertaining.

Agree! I care about trend. And frankly, my trend is going nowhere right now. I've been bouncing between 14 and 15 for almost 2 months now. I'm changing things, so I expect to see some changes in numbers soon. I suspect my BF% will go up until I finish gaining, then I'll bring in cardio.

your $40 scale is as accurate as you need it to be. bottom line, your scale isn't going to read BF as 30% when you're actually 10%, it's not going to read 10% if you're actually 30%... it might read 22% when you're actually 20%, but so what?

ignoring the scale because it's not accurate is another one of those 'built-in excuses' we're trying to purge from our lives.

Edited by: MRPLATSON at: 5/4/2010 (09:22)

Ouch, I clicked the link.... now my head hurts. Even the pictures made me dizzy. Gracefulife, I had to jump to the bottom where it says conclusion. And the result? More studies need to be done, oh and you need a different equation based on ethnicity and a whole lot of other crazy stuff. I guess my 40$ scale is not accurate :)

I'm pretty sure neither method is said to be "accurate" in the sense that they have the right number. Both are said to be good for tracking relative changes, though. I've read that BIA is better for people with high BF percentages because caliper measurements become meaningless beyond a certain level. We all know that BIA is strongly affected by water balance - and Skwigg says you can make it read lower by having a belly full of meat (actually I think that's true - it read really low the morning after a big meal of home-smoked meat - mmm Q). I think I've read that BIA has problems when you get to extremely low BF% (as in single digits). Also, BIA only measures lower body or upper body unless you are having the clinical version done or using one of the newfangled scale-handgrip combination units. Calipers have the advantage that you can just directly compare the BF caliper measurement to last week's measurement, and therefore you can get an idea of how body fat distribution may be changing as well as levels. That's why Venuto recommends that you log the actual caliper readings, not just the calculated BF% numbers. That's especially true for competitive bodybuilding where your look determines whether you have gone far enough anyway and the calipers are just to verify that you are progressing toward the goal. Also with calipers you can use single-point, 3-point, or 7-point methods to calculate body fat percentages. There might even be more than 7 places that skinfolds can be / are routinely taken.

So once I distilled all that, and also have tried out some calipers (though unfortunately not pro-style yet), I came to the conclusion that neither was perfect. Therefore I use BIA daily with the PD smoothing since it is most convenient. I use calipers as a double check to verify the realism of the BIA value (especially when deciding what mode to run a BIA device at, like when I switched to athlete mode). I may use the actual caliper measurements as an indicator in the future. I'm planning to get a DXA scan once I am close to goal which will give me a real idea of where I am. In reality that's probably more just for giggles more than anything else since doing it one time doesn't directly relate to my goals. It might relate to what sort of crazy diet regime I need to try out to improve if I still feel some kind of crazy need to do so (hope not).

One I've studied enough, it might be interesting to draw some diagrams of how many levels of calculations / lookup tables / etc. are used to get BF% out of each of the methods. I was surprised at all the calculational gyrations happening behind the scenes when going from caliper measurements to the BF% number when I looked into it.

So I've heard a mixed bag with regard to accuracy. Some say its a lot more accurate than calipers, mostly because calipers are highly prone to user error. In software, I like to call these PEBKAC errors. But can BIA beat a reasonably skilled human?

I don't want the gist! It appears that I've found something to explain it in the level of detail at which I'm interested. The wiki page en.wikipedia.org/wiki/Bioelectrical_
im
pedance_analysis links to this report www.ake-nutrition.at/uploads/media/b
ia
1_Kyle_et_al.pdf -6 figures, 6 tables, 113 technical references. Now you're talking.

The more I read this site the more it seems like a shill for Tanita, but it IS informative.

The gist is .. they send electrical signals through you and get back a number that is then compared to known readings, of other more accurate tests, based on gender, age and other parameters. BIA testing has become more accurate over the years then when it was originally invented 30 years ago. Still no at-home test is going to be as good as having it done clinically.

- www.new-fitness.com/bioelectrical.ht
ml


- www.new-fitness.com/body_fat_analyzi
ng
.html

- www.new-fitness.com/body_fat_measuri
ng
.html