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.

http://www.youtube.com/watch?v=wPy-D9LZQqM

[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.

[OptikaNET]

Hi, my calipers arrived today. Just tried them out (averaging 4 readings - all of which read the same anyway). Got a fat-percentage value of 19.6. Used my Tanita balance and got a fat-percentage of 20.6. I'd say they were reading pretty closely the same and since the calipers cost £3.99 and a flimsy piece of plastic and the balance cost £500 and is a complex, calibrated piece of precision electronics, I'm inclined to believe the balance!

Interesting experiment though.

Kind Regards
Dave

[Deviation]

Well paying $500 certainly makes you more inclined to believe it. ;) Besides 1% variance either way isn't a bad margin for error.

[OptikaNET]

That depends... when I worked with radioactive-labelled compounds in the lab, my error margin used to be 0.05%!!!

I would have found a 1% error margin horrendous!!!

Kind Regards
Dave

[Deviation]

That depends... when I worked with radioactive-labelled compounds in the lab, my error margin used to be 0.05%!!!

I would have found a 1% error margin horrendous!!!

Kind Regards
Dave
LOL. Well I didn't mean EVERYTHING.

[OptikaNET]

Learn to cultivate a sense of precision dear chap!

Kind Regards
Dave

[femaveeick]

One problem with BIA scales is that they don't handle people with thicker than average skin (which has more impedance). Or people who's thickness of skin varies often. Unfortunately I fall in that small group of people. I deal with psoriasis, which is an overactive immune response in the skin organ. I can't trust BIA even for trends of information. It's currently reading me at about 30% BF when just a month ago it read me at 25%--and I lost fat between now and then. I've even had the thing give me different answers when reattempting the measurement 3 times in a row.

At least with calipers, my trending is more accurate (for me).

[OptikaNET]

Hmmm... that's true. I often wonder if my skin has increased conductivity after a bath than at other times when it might be drier and whether that affects the reading or not, as well.

Still, it beats looking at your wobbly belly and saying to yourself; "Am I losing any fat at all?"

Kind Regards
Dave

[femaveeick]

Hmmm... that's true. I often wonder if my skin has increased conductivity after a bath than at other times when it might be drier and whether that affects the reading or not, as well.


Oh, that's absolutely the case. You'll also find that you retain more water at the end of the day than at the beginning. That means you will have the perplexing case where at the beginning of the day the BIA scale says you weigh less but have more fat; but at the end of the day you weigh more and have less fat. Water conducts electricity better, so it treats it as lean mass.

[OptikaNET]

That's why I always weigh myself when I get up in the morning; before I have eaten or drunk anything but AFTER I have been to the toilet...

Kind Regards
Dave

[John Rippon]

Ah - the inevitable debate about measuring, or perhaps more correctly - estimating total body fat.

Some facts:
Estimating total body fat to accuracies of better than 1% are complete bollocks.
All estimates based on various tape measurements, all calipers, most BIA methods (e.g. Tanita scales) do not take into account the whole body but make assumptions about what might be in the whole body based on - at worst a crude measurement of subcutaneous fat thickness as a single point; at best a rough estimate of body composition over the lower body (path taken by the current between the electrodes on a BIA scales). While some of these methods may give a reasonable estimate of the amount of fat over certain areas, they all rely on extrapolating from there to give an estimate of total body fat based on empirical formulas that have never really been subject to solid scientific verification. If you have lots of subcutaneous tummy fat, the assumption is that you must have proportionately lots of visceral fat throughout your body. Put an age adjustment in to take account of the notion that, if you are older, you will probably have proportionately even more visceral fat. Question: How do they come up with these empirical formulas for such an extrapolation? Answer: If you're lucky they might have done so by assuming that determination of overall body density by means of total immersion is 100% accurate, then taken lots of samples over a broad range of subjects (gender, ethnicity, 'body type', age, etc. etc.). Again the likelihood of that being the case is bollocks. These formulas makes gross approximations as to the proportions of various constituents of the body, and about the absolute densities of each of those constituents. As but one example, most people are aware that mineral bone density can vary considerably from one individual to another. etc. etc.
If you are still in any doubt about how body fat estimates made by different methods give inconsistent results: Personal example. I once had my BF estimated by three methods all within an hour of one another: Cheap plastic digital calipers (Jackson/Pollock 3-site measurement): 8%, Expensive Harpenden calipers (Jackson/Pollock 3-site measurement): 10%, Very expensive DEXA scan (whole body dual-energy X-ray analysis) 14+%.
There are likely only two reasons why you think you want a BF% number for yourself: a) You want to compare it against the figure you've read or hear for someone else. b) You want to have a set of numbers over time to content yourself that there is a trend in the direction that you desire. I hope I've dispelled the idea that reason a) is pointless. b) seems a more 'reasonable' reason, but given my next point, I hope you'll see that placing reliance on such a set of numbers is dicey unless the trend is quite apparent (in which case your camera, mirror, clothes and friends are probably a better guide than the set of numbers).
Apart from inconsistencies between different methods of estimating BF illustrated in 3) there is also the problem of inconsistencies between different measurements taken by the same method. With calipers the biggest variation is generally due to inexperience and/or poor technique on the part of the person taking the measurements. Other factors also have to be eliminated - such as different levels of hydration at the time of measurement, stance and degree of relaxation of the subject etc. If I were to hazard a guess as to what would be a fair error estimate for an experienced person estimating BF by calipers and following all the prescribed procedures for doing so, it would be nearer 1% for low body fat (e.g. < 10% men, < 15% women) or perhaps twice that much for people nearer the 20%+ range. These are only guesses, but quoting figures to 0.1% are meaningless. There are also some subjects for whom it is very difficult to separate their subcutaneous fat from the underlying tissue. For these people (I've come across a few) it's virtually impossible to take any meaningful measurement at some sites.
Bottom line as far as my advice is concerned is: Don't bother about BF% figures unless you are confident that the method you are using gives consistent results (and you need to prove this). Even if you do, don't even think about comparing your figures with those of someone else. Bodybuilders who say they are 3% BF better go and get a DEXA scan. The guy who took mine in Australia has dealt with hundreds of bodybuilders over several years and told me the lowest figure he got for a guy who was absolutely shredded was 8%.

[femaveeick]

Well said. I do the caliper method, but it is strictly for checking my trends with myself. Essentially, evaluating the effectiveness of how I eat. I'd give just about anything but a DEXA scan 2% error. And I'd give BIA scales a 3-4% error margin for me. Anything smaller than that is, as you've pointed out: bull.

[peterbrown77]

Right - absolute BF percentage I really only care about to establish a caloric baseline using Klatch-McCardle or Harris-Benedict. Even that has to be adjusted based on actual results. After that, it is just for evaluating whether you're progressing or getting fatter!

[Shanu82]

Not to sure where to log this so thought I'd try here.

Trying to reduce my body fat but in terms of measurement I've only got a set of scales that measure weight, BF and hydration. I've seen some BF calipers and wondered how are these in terms of accuracy? Are they a worthwhile investment?

The scales seem very erractic in their measurement so I'm looking for something more accurate or consistent.

Thanks.

[OptikaNET]

Hi Shanu,

I have merged your post with an existing discussion on BodyFat and I have moved that discussion from the "Welcome" section of the forum because I felt that it was in the wrong place. I hope the previous posts will help answer some of the questions you have and I hope you enjoy the discussion.

Kind Regards
Dave

[Shanu82]

Been a good informative read guys. I've managed to learn that no method is exact and should only be used for tending purposes providing the measurement method is consistent.
Think I'll have a go with the calipers as well as the scales and believe which ever gives me the smaller number.

[OptikaNET]

Believe whichever gives you a consistent number!!!

Kind Regards
Dave

[OptikaNET]

My cheap and nasty skinfold calipers say my bodyfat% today is 13-14%. With the spare tyre I still have around my waist (a good 5kg worth I'd say...) this is clearly incorrect. My Tanita puts me in the 18-19% which seems more realistic.

I'm still convinced that, of the two, the Tanita is the more accurate.

Kind Regards
Dave

[peterbrown77]

Okay, so here are some real-world results from my Tanita. I started using the BFFM program combined with P90X2 on Christmas Day. I weighed 188 lbs. My Tanita said I was 23.5% body fat. Now, two months later, I weigh 172 lbs, for a loss of 16 lbs. My Tanita this morning said my body fat is 21%.

Patently, the Tanita is full of crap. I've lost 16 lbs from a total of 188 lbs, or over 8% of my total body weight. Assuming the Tanita was correct at 23.5% initially, that meant I had 44 lbs of fat and 143 lbs of lean mass. Now I have 44 - 16, or 28 lbs of fat from a total of 172 and we'll assume my lean has not increased, so my body fat percentage is about 16%. However, the Tanita consistently puts me at 20% - 22%.

Empirically, the Tanita is not even close to accurate.

[Saint78]

Soooo, jumping in here.

First off, I'm not working out to get as low body fat % as possible or keeping track of it for any other reason than keeping track of it. Now it would be stupid to say that it's NOT important to me, it is to some extent, but it's not my motivation for working out. I'm kind of nerdy and all those numbers talk to me hehe.

I have a Tanita at home which I use regularly. As it's not exactly accurate (there are a LOT of variables), but it IS great for one thing. Measuring change over time and finding your trend. Going up or going down? If you want accurate % then this is almost as good as looking in the mirror. But it gives you your weight accurate and the rest is "nice to have". I use this with an app on my smartphone to track the numbers.

I also go to a rehab facility for sports injuries, they have a GE InBody720. It's quite expensive, so it's not that common. But it's the most accurate out there. It also measures visceral fat (the dangerous stuff) quite accurately, but this also has some variables. I know for a fact that the hospital in my area use this on patients with medical issues because thay are obese. It's supposedly "medical accurate" It gives you fat, water, muscle in each limb, bone etc. You get a nice printout to keep track of your progress.

The InBody (or Tanita to a lesser extent) is great for keeping track of nutritional changes or changes to your workout. I do a lot of seasonal specific sports and the InBody shows me that during winter, the muscles in my legs increase quite dramatically and in summer my upper body/arms do the same. Vice versa, my legs go skinny in the summer.

Again, why you choose to keep THIS much control over details is up to you. If it motivates you, then good for you. I use it to find out when I should cut back on the pizza.

http://inbody.gehealthcare.com/products/inbody-720