Body Fat

[albertus]

Hi All

Barry from South Africa here....
I just joined the site and hitting gym starting from 30th of Jan.
I would just like to ask how does one measure their own body fat?
Any advice would be much appreaciated!!!!
Thanks a Lot!

[Deviation]

Welcome to the site. There's a few ways to do it. One method is to use a scale that calculates body fat (not BMI). They range anywhere from $80 to $500 depending on features. http://www.tanita.com/en/personal/ makes several. Another method is calipers. This takes practice to get right.

[peterbrown77]

I have both calipers and a Tanita bodyfat scale. I think the Tanita is okay to measure change in bodyfat, but it's absolute number is woefully inaccurate. I think it calculates BMI first and then tries to make adjustments. I'm fairly muscular, and 5'8" and 175 lbs. Several caliper-derived measurements put me at about 17%-18% but the Tanita tells me - day after day - that I am 23% - 24% bodyfat. That's classified "obese" and I'm definitely not. So, measuring increase or decrease in the percentage is probably the Tanita's strong point but as for it telling you where you actually are? Forget it.

Calipers are cheap and easy - and remarkably accurate.

[Deviation]

I agree with you. I don't have the fancy $500 scale (nor do I plan on getting it). My Tanita scale is fine to guesstimates. It puts me around 24%. First time using calipers put me around 20% which is probably about right. Still working on getting it a little more accurate with calipers. Takes a bit of practice.

[OptikaNET]

Tanita doesn't use BMI, it uses conductance and impedence measurements arising from directing a pulsed electric current through the body. Fat conducts electricity more poorly than muscle does, and both are subject to changes in the conductance of pulses, so by varying the current and the pulse frequency an accurate measurement of fat percentage can be derived.

The method has been shown to be more accurate than calipers, but less accurate than the floatation tank method.

Now, how this translates to the device you have at home, how good the calibration of said device is I cannot say. Certainly the £100 hand held device they use at my local gym (not made by Tanita) and my £500 Ironman Tanita balance give greatly differing results. The values I get at various gyms tend to differ hugely from each other, the value from my Tanita balance is quite consistent. When I am dieting it falls, when I am not paying attention to my diet it rises. Values always seem consistent historically and with my behaviour patterns.

By way of an experiment, prompted by this thread, I have just ordered a set of calipers to see what they will read. However, since said calipers only cost £3.60 from Amazon I will take any value they give me with a pinch of salt.

Just a final point, Tanita balances have to be on a stable hard surface to work. Make sure they are not on carpet or anything or they will read the weight incorrectly and therefore will give a false fat value (since the estimation process takes weight into account).

Kind Regards
Dave

[Deviation]

BIA isn't more accurate than calipers. I know the fancy scales (like yours) can supposedly read out body composition. Those are probably pretty close to what you'd get on calipers and more accurate than the basic BIA scales. The issue with calipers is the person using them (human error). I take measurements 3 times and average them. Though I will say its tougher to do on yourself.

[peterbrown77]

I know that the Tanita doesn't use BMI - what I was trying to imply is that I think that, based upon your initial inputs of height/weight/age it makes a certain assumption of your body fat percentage that doesn't necessarily comport with your true value. In that way, it is similar to BMI in that it doesn't consider body type - just height and weight and therefore begins from a false premise. From that starting point, I think it then adjusts its initial value by using the impedance. So if you're muscular and average height, and therefore "heavy" for your height, it assumes the extra weight is fat. So maybe it guess-timates you are 25% and then takes it's impedance value and adds or subtracts from it. In truth, you might only be 16% BF. Right from the start I suspected this because, if impedance is actually accurate then why did it ask my for my height and age? What difference should that make to the resistance of my body?

[OptikaNET]

The cheaper ones may have a problem with that (certainly the £10 one I bought from the local chemist was wildly inaccurate) but the Ironman balance I have has a different setting for whether you exercise regularly or whether you don't. Obviously it's going to make assumptions, anything on wide distribution would have to, but the assumptions made will depends on the suitability of the device and the Tanita website states that if you are athletic then certain models won't work for you.

The question then is, did you buy the right model?

[OptikaNET]

I have my doubts about calipers because they only measure subdermal fat and are not capable of measuring visceral fat, which my Tanita CAN measure.

I haven't researched this, but I doubt there is a direct correlation between the one and the other - I would expect genetic factors to make that rather variable and I KNOW that gender-factors alter fat distribution so it's reasonable to assume that this would also vary according to hormonal levels.

Visceral fat lies underneath the muscles, shrouding the organs and the digestive system so cannot possibly be measured by a device pinching the skin.

[peterbrown77]

Well, you've only three methods to measure your bodyfat. Actually, there are 4 - the fourth is dissecting your carcass and cutting away all the fat and putting it on a scale, but we won't go there. The first - and supposedly gold standard - is being weighed while submerged. However, if you don't expel all the air from your lungs that will lead to errors. Then there are calipers, and finally using impedance. I've read on them a lot, online and on Tom Venuto's book and the calipers are uncannily accurate. Even the three versus eleven point method only yields a percent discrepancy when I do it. And who is going to freak if they are 9 instead of 8 percent? What is important is not so much the absolute number, but the trend. The number is only important in developing your diet and caloric intake. That isn't set in stone either, but only a starting point. If it tells you to go for 2200 calories and after 2 weeks you haven't lost an ounce, you go to 2000 and see what happens. Or maybe 2200 just slays you, you're crashed - then you go to 2500 and see what happens.

So regardless of method, it is the ease and repeatability of the measurement that counts. If your Tanita repeats, great. Mine has never been consistent though but the calipers - even the cheapo white plastic ones - seem for me to measure the same each time.