PDA

View Full Version : Tanita BC-418 Segmental Body Composition Analyzer



fabians94
03-09-2012, 03:36 AM
http://www.tanita.com/en/bc-418/

Since my gym has this particular machine, I've been relying on this machine for the past four months to obtain my body fat percentages, weight and muscle mass.

My question is, does anyone have an idea how accurate are the results from this machine?

keyboardworkout
03-09-2012, 05:35 AM
These are about as accurate and a whole lot cheaper.

http://www.amazon.com/Koplow-Opaque-Sided-Black-White/dp/B001F2ZKZM

fabians94
03-09-2012, 08:50 AM
These are about as accurate and a whole lot cheaper.

http://www.amazon.com/Koplow-Opaque-Sided-Black-White/dp/B001F2ZKZM

Trolling aside, is the machine reliable enough?

ironwill2008
03-09-2012, 11:09 AM
Trolling aside, is the machine reliable enough?

He's not trolling you, OP; he gave you an honest answer.





Any such gizmo that relies on bio-electrical impedance is going to provide you with little more than a guess. They're even worthless for relative readings, since you'll see as much as a 5% difference in your own results in the same day.


Personally, I just go by what the mirror and the fit of my clothes tell me, but if you must know a number, and expect it to be accurate (if it's not, why bother at all?), find someone locally who does hydrostatic body fat testing.

dumb.bell
03-09-2012, 11:15 AM
These are about as accurate and a whole lot cheaper.

http://www.amazon.com/Koplow-Opaque-Sided-Black-White/dp/B001F2ZKZM


LMFAO - That was a good one. But very true!!

fabians94
03-09-2012, 06:35 PM
I really feel that it's important to get these readings accurately.

Thank you guys for your help.

danbradster
01-01-2013, 08:16 PM
I find it reasonably accurate, you can see my Tanita BC 418 Review (http://www.sportsscience.co/equipment/tanita-bc-418-segmental-body-composition-analyzer-review/).

I did 2 tests 1 month after each other. It reported my body fat to have increased by 0.1%, so I think the random variance is quite small. In reality, my body hadn't changed composition much, so a 0.1% increase is realistic. It still varies depending on your hydration level, so it's most accurate if you have the same diet/behavior before each of your tests.

The 4 points of contact (feet and hands) is superior to any 2 points of contact (feet or hands) machine.

SESnut
01-01-2013, 11:33 PM
It reported my body fat to have increased by 0.1%, so I think the random variance is quite small. In reality, my body hadn't changed composition much, so a 0.1% increase is realistic. It still varies depending on your hydration level, so it's most accurate if you have the same diet/behavior before each of your tests.


do you realize how stupid you sound when you say **** like this?

0.1% of your weight is 0.144 pounds.

danbradster
01-02-2013, 02:12 AM
do you realize how stupid you sound when you say **** like this?

0.1% of your weight is 0.144 pounds.

I said 'increased by'.

SESnut
01-02-2013, 11:27 AM
I said 'increased by'.

how does that make it any less ****ing stupid?

your ****ing shirt probably weighs more than 0.144 pounds or the liquid in your bladder.

herp derp

danbradster
01-02-2013, 07:34 PM
how does that make it any less ****ing stupid?

your ****ing shirt probably weighs more than 0.144 pounds or the liquid in your bladder.

herp derp

Ok. So I guess you're suggesting that a superior tool would lose that 0.1% of possible inaccuracy.

If the bio-electrical impedance is working however, if will be analyzing the impedance in my muscles rather than shirt. Also the Tanita BC-418 lets you enter the weight of your clothes which it removes from your total weight.

SESnut
01-02-2013, 08:48 PM
Ok. So I guess you're suggesting that a superior tool would lose that 0.1% of possible inaccuracy.

If the bio-electrical impedance is working however, if will be analyzing the impedance in my muscles rather than shirt. Also the Tanita BC-418 lets you enter the weight of your clothes which it removes from your total weight.

Did you actually weigh your shirt or did you guess?

It measures impedance through WATER. Water levels in your body vary throughout the day.

If youre trying to tell me you did the EXACT same thing a month later, you still wouldn't be able to tell me that the water level in your body was exactly the same as before.

In other words, you sound ****ing stupid.

danbradster
01-03-2013, 12:13 AM
Did you actually weigh your shirt or did you guess?

It measures impedance through WATER. Water levels in your body vary throughout the day.

If youre trying to tell me you did the EXACT same thing a month later, you still wouldn't be able to tell me that the water level in your body was exactly the same as before.

In other words, you sound ****ing stupid.

I sound stupid for using the machine or what?

I entered the same weight for my clothes each analysis.

What method would you suggest that is more accurate? Should the gyms using these machines cease using them?

Aussieguy101
01-03-2013, 12:35 AM
Its criminal that a machine costing over 5 K using this technology. I am sure it is more accurate than those hand held models or the bathroom scales but still not accurate enough for a 5K machine

ICEcap2
01-03-2013, 01:40 AM
Its criminal that a machine costing over 5 K using this technology. I am sure it is more accurate than those hand held models or the bathroom scales but still not accurate enough for a 5K machine

IMO it's OK to charge whatever you what, but if anyone buys one at that price they are misinformed at best and probably much worst. I have a cheap Tanita scale about $100 years ago. It works OK as an relative indicator if you eat the same and take the measurements at the same time under the same conditions. I get reading variations of about +-1.5% when I know my body fat really didn't change that much.

danbradster
01-03-2013, 02:09 AM
The more expensive machine has 4 contact points instead of 2, which should improve the accuracy. At least with me it reported the same body fat percentage (0.1% increase) 1 month apart. So that machine likely doesn't have the 1.5% variance that your cheaper scale had.

62Wolf
01-03-2013, 04:27 AM
I've never used one and I'm not sure if it's the same exact model, but I can tell you that there was basically a mutiny at a local gym that got one. There is a pretty decent winner's prize at the end of these programs that the gym does, Trip for 2 to Hawaii, plus some really good runner-up prizes. It was a disaster. For one example, it said that an obese woman was @ 18% bodyfat, whereas it "measured" an absolute cardio animal with hardly any fat at all and with good muscle mass as @ 38%. There were a lot of other "measurements" like that also. Owner refused to give in and go back to a different way of measuring because of the cost of the machine. The company that sold it to him would always come up with a different reason/excuse everytime he contacted them, but would not take it back for a return. My wife, who is one of, if not the best athlete at that gym, got measured once on it, laughed and vowed never to use it again. She was ripped when they tried it on her and it said something like 29-31% bodyfat, while a classmate of hers got a 17% reading and that woman hasn't seen her toes while standing in probably 15 years.

KalleA
01-03-2013, 04:30 AM
The more expensive machine has 4 contact points instead of 2, which should improve the accuracy. At least with me it reported the same body fat percentage (0.1% increase) 1 month apart. So that machine likely doesn't have the 1.5% variance that your cheaper scale had.

One should perhaps ask oneself "accuracy of what, exactly"...

What a bio-electric impedance bodyfat analyzer does is measure "some resistance" in your body. This is really important to understand: it does not, and can not, measure your bodyfat. It makes a stab at guesstimating your bodyfat, based on the measured resistance plus stuff like your weight, gender, heigth, age and (sometimes) body type.

Here's a hint for the critical thinker: you are asked to input your body type as "standard" or "athletic". Now, how much more accurate do you think the computation is going to be than the somewhat arbitrary "standard" and "athletic" inputs...? Why not, say: "not athletic" "standard", "a little bit athletic", "a little bit more athletic", "quite athletic" and "very athletic". That ought to improve accuracy, right? Hopefully, you do realise that your input of "standard" or "athletic" is giving the machine your rough estimate about your level of bodyfat. How accurate is the method likely to be if you need to provide your own assumptions about the stuff it is supposedly "analyzing"?

So, accuracy of what? Accuracy of measuring "some resistance", that's what. What does that mean? Not very much, unfortunately.

The machine may have a more or less accurate measure of "some resistance", that relates to your hydration levels. It then takes this measure and tries to calculate your body composition by entering your height, age, weight, gender and your own opinion regarding standard/athletic bodytype into "some algorithm".

The critical mind might now ask: "what is this algorithm based on, and why does it need my age, gender and my own guessees?" Pretty good question, right?

The answer is that the algorithm is based on a benchmark population of people, who have been tested on the machine. A few questions might now spring to mind: "how many people were actually used in this calibration?", "might ethnicity also be a factor?", etc. But, the most important question must be: "If you use a number of people to develop the algorithm and "calibrate" the machine, how do you know their real bodyfat to begin with?"

The answer typically is: by hydrostatic weighing.

The ensuing question: "Aha, what does hydrostatic weighing actually measure, and how accurate are it's bodyfat numbers?". The answer, somewhat disappointingly: "It actually does not measure bodyfat, it measures body volume, and then guesstimates bodyfat from that..."

Yup, hydrostatic weighing is another guesstimate thingy. It's accuracy is typically 4%.

That, in summary, is the bioelectric impedance method: a guesstimate calibrated by another guesstimate


Which method do you suggest that is more accurate?

You want a more accurate guesstimate of your bodyfat level: look in the mirror! Is that accurate? Or course not, but it is likely to be more accurate than bioimpedance. It is also a lot cheaper, and it does not give you a misleading impression of "accuracy".

Want the most accurate guesstimate available? Get a full body MRI.

An MRI is by far the most accurate method for estimating bodyfat. It will be accurate within 2%, which is superior to any other method.


Cheers

Porphyry
01-03-2013, 08:40 AM
One should perhaps ask oneself "accuracy of what, exactly"...

You want a more accurate guesstimate of your bodyfat level: look in the mirror! Is that accurate? Or course not, but it is likely to be more accurate than bioimpedance. It is also a lot cheaper, and it does not give you a misleading impression of "accuracy".

Want the most accurate guesstimate available? Get a full body MRI.

An MRI is by far the most accurate method for estimating bodyfat. It will be accurate within 2%, which is superior to any other method.


Cheers

I was going to write something along these lines then I looked at his website and realised it was a waste of time. Good post, wasted on the wrong dude. Repped anyway.

Danbradster: Those are some of the stupidest posts I've ever seen in this forum. Aren't you meant to be over in the misc?

I'm just going to comment to the OP that we see these bio-impedance questions every other week but even given the better body fat measuring accuracy of an MRI - a mirror is by far THE most accurate measurement of what most people actually want.

That is: to look good.

Why try to assign a number to that? If you have 5% BF at 5'10", 120lbs and look like a piece of beef jerky do you win a prize? What about 20%BF at 220lbs? Which would you rather be? When you ask for a girl's number does she ask you what your BF% is?

TL;DR:

Bio-impedance measures impedance which sort of correlates to hydrostatic volume which sort of correlates to total body fat which is sometimes inversely related to "looking good"
Calipers measures subcutaneous fat thickness which correlates to total body fat which is sometimes inversely related to "looking good"
DEXA measures tissues density/absorption which more closely correlates to total body fat which is sometimes inversely related to "looking good"
Mirrors measure "Looking Good"

SESnut
01-03-2013, 01:44 PM
I sound stupid for using the machine or what?

I entered the same weight for my clothes each analysis.

What method would you suggest that is more accurate? Should the gyms using these machines cease using them?

you sound stupid for saying your bodyfat went up 0.1% and the machine is accurate

I could look at 2 pictures of you taken 2 seconds apart and say the same ****ing thing and be just as accurate.

ICEcap2
01-03-2013, 01:55 PM
The more expensive machine has 4 contact points instead of 2, which should improve the accuracy. At least with me it reported the same body fat percentage (0.1% increase) 1 month apart. So that machine likely doesn't have the 1.5% variance that your cheaper scale had.


you sound stupid for saying your bodyfat went up 0.1% and the machine is accurate

I could look at 2 pictures of you taken 2 seconds apart and say the same ****ing thing and be just as accurate.

No known fat measuring method included autopsy is accurate to 0.1%. I bet the variance of the 5K machine is much more than that through the day. Just use it to measure your fat each hour and report your findings. I bet it will be at least +-1% with the 5K machine. IMO not worth 5K where my cheap scale gives almost the same results.

IMO these are made to sell to the "fancy" health clubs so their members can use them and feel "special." Maybe there is a remote to move the % down to make people feel better. I seen some gyms where their scales always read light, same idea.

Aussieguy101
01-03-2013, 02:44 PM
IMO these are made to sell to the "fancy" health clubs so their members can use them and feel "special." Maybe there is a remote to move the % down to make people feel better. I seen some gyms where their scales always read light, same idea.


Yeah i went to a gym with one of those in my early 20s. Only good thing about that gym was the amount of chicks i used to pick up (that was in my young dumb and full of c*m years)

And if people did put on weight even with the "light' scales the trainers would say it's because they gained muscle, even to the middle aged women who only did the aerobics classes and clearly haven't gained any muscle

jmmainvi
01-04-2013, 10:07 AM
I sound stupid for using the machine or what?

I entered the same weight for my clothes each analysis.

What method would you suggest that is more accurate? Should the gyms using these machines cease using them?

Using bioelectrical impedance for measuring bodyfat is really a joke.

Conditions that need to be fit for these machines to read accurately:

- Before beginning to fit the rest of this list, subject should be "normally" hydrated and on a "normal" food schedule (varies person to person)
- Subject should be fasted for 12 hours before testing
- Subject should not have drank any liquids for 4 hours before testing
- Subject should have Urinated 30 minutes prior to testing
- Subject should not have completed any exercise 4 hours before testing (anything harder than moderately pased walking qualifies; anything that gets your breathign rate up.)
- Subject should not have completed any strenuous exercise 12 hours before testing (lifting weights, sprinting, swimming, rowing, anything that gets your heartrate over ~120 bpm)
- Subject should not have taken any medications or supplements in the last 12 hours
- Subject sould not have experienced significant recent weight loss/gain, or any recent extreme diet changes
- Site of electrodes must be shaved, dry, clean, and undamaged with conducting gel applied.

All of these factors will mess with how your body stores water, or how the non-water composition of your body conducts the electrical current. Even in laboratory settings where we controlled as many of these as possible, we took three readings, 10 minutes apart and found 3 values, which differed on an average of more than 1%. This was with a "laboratory quality" bioelectrical impedance device, worth thousands of dollars, and it still wasn't actually acurate enough to provide meaningful data.

If you really "need" a measurement, the best way to go in terms of equipment is calipers, but even those are prone to user error and you'll need another person to help you take the measurements. The best way to track your body composition is through the mirror in the morning before you shower. Take a picture every few weeks to help ou withyour comparison. Good Luck.