Reliable way to measure body fat percentage?

neeb
neeb Posts: 4,473
edited February 2014 in Training, fitness and health
When I've looked into those fancy scales that supposedly measure body fat percentage, I've come away with the impression that they are not very accurate or reliable. Is this still the case? My weight doesn't vary that much anyway (2kg at the most), so anything that is of use to me would need to be reasonably accurate or at least consistent.

Presumably you can use variations in total weight together with body fat percentage to calculate variations in muscle mass?

P.S. I know that the most accurate way to do it is with a highly trained human being and calipers, but I don't think I could persuade my GP to do that... :wink:

Comments

  • richard_farrant
    richard_farrant Posts: 231
    Why dont you try those scales that you find in shopping centres?
    Dolan Mythos
  • neeb
    neeb Posts: 4,473
    Richard Farrant wrote:
    Why dont you try those scales that you find in shopping centres?
    Haven't seen one of those. But I guess they work in the same way as the ones you can buy, i.e. they pass an electric current through you and measure resistance? I've heard it's not very accurate, as you would sort of expect - can't take account of individual variation, percentage of bone vs. muscle etc.
  • richard_farrant
    richard_farrant Posts: 231
    Might give you a rough estimate though, and only cost you 50p...
    Dolan Mythos
  • diamonddog
    diamonddog Posts: 3,426
    I tried the electronic scales and various online formulae given on here and they all came out near enough to what I know my BF% is.
    This is one that was about right for me just using the simple measurement option at the end.
    http://www.linear-software.com/online.html
    or this one
    http://www.scientificpsychic.com/fitness/diet.html
    None will be 100% but might be close enough for you.
  • BenderRodriguez
    BenderRodriguez Posts: 907
    neeb wrote:
    I know that the most accurate way to do it is with a highly trained human being and calipers, but I don't think I could persuade my GP to do that...

    Why not just buy some cheap body fat calipers and get your partner to do the measuring, or even yourself? The 'training' you need is minimal. I have some and the results I have got over the years agree with those taken by a professional within about 1%.

    The 'Slim Guide' one's I bought still only cost about £18.
    "an original thinker… the intellectual heir of Galileo and Einstein… suspicious of orthodoxy - any orthodoxy… He relishes all forms of ontological argument": jane90.
  • neeb
    neeb Posts: 4,473
    Thanks for tips - yup, after looking at that link from diamond dog above it looks as if doing it with calipers doesn't need a degree in anatomy.

    How reliable is the tape measure method as a matter of interest? (using neck measurement, abdomen measurement and height).
  • diamonddog
    diamonddog Posts: 3,426
    It was more or less on the nail for me in comparison to the other link and what I already know but this may not always be the case, IMO calipers are the best and most accurate method.
  • mpatts
    mpatts Posts: 1,010
    I did one of those electrical resistance things at the gym - came up with 25%.

    I am 64kg and 5ft 9. I had a CT scan recently and the first thing the doctor said to me was "Are you are cyclist or something, because you have almost no fat"
    Insert bike here:
  • mentalalex
    mentalalex Posts: 266
    I have found with scale based systems once they seem to be way off, only from personal experience having had anything between 6%-11%

    Callipers are good as well.

    Had a DXA Scan last October when winter training properly started, it was 15%.
    I do science, sometimes.
  • ride_whenever
    ride_whenever Posts: 13,279
    A certain ex-pro around here always carries fat calipers and tends to attack people with them and tell them how fat they are...
    Neeermad
    Carbon 456
    456 lefty
    Pompino
    White Inbred
  • neeb
    neeb Posts: 4,473
    The neck & waist measurement methods give me about 11-12%. I'm 5'9" and 63kg. I'm slender boned though, and it seems to me that I still have moderate fat deposits in the love-handle area, i.e just above the pelvis at the sides/lower back. Maybe I am anorexic.. :wink:

    Maybe I could still healthily lose a couple of kilos without significantly impacting power output?

    Need to try the callipers...
  • bahzob
    bahzob Posts: 2,195
    I think body fat scales get a bad press, often I suspect from those who don't like the readings they are given.

    Like any other measure the key thing is not to take one reading and take that as gospel. Rather you need to take consistent readings over time and see if that establishes a trend. Chances are it will. I have been using some Tanita scales for 5 years now and, not surprisingly, as my weight has come down from 80+to 69kg so has fat % from 28%+ to around 14%. More interestingly now I am at constant weight fat% can still differ, due to the nature of training/diet and this helps work out what training is effective and which isnt. I've tried the alternative of calipers and found that to be less reliable, especially when you are at lower fat levels where a mm +/- makes a proportionately larger difference.

    In absolute terms the scales also are not too bad, I had a Bod Pod test and that came to within 1% of what my scales were saying.

    A more complete review DC Rainmaker did a very thorough analysis of them compared to the Bod Pod the results of which were further summarised here
    http://www.dcrainmaker.com/2011/09/bod-pod-consumer-scale-comparison-tests.html

    Conclusion of which was

    All the scales tested give BF% measurements that is not statistically different than what the Bod Pod will spit out ...

    Of course, these data say nothing about the absolute accuracy of the BIA scales or the Bod Pod, they are merely comparing the different devices. If we wanted to say something about the accuracy of the devices, we’d need to be comparing them to the gold standard measurement technique (DEXA) and we don’t have that data at this time. BIA scales and Bod Pod typically have an accepted accuracy of 3 BF% or so and we need to remember that. It could be theoretically possible that the scales are hitting the absolute BF% right on and the Bod Pod is the device that is missing the target....

    While we don’t know about the accuracy, the BIA scales are overwhelming precise from my and others experience. If you measure the same way every day (i.e. methodology including hydration), the readings day to day will be consistent allowing you to follow trends in the data to see how your BF and lean mass are changing over time...

    After seeing the data and analyzing it, I’m confident that the scales are a reasonable alternative to more expensive testing like the Bod Pod if you want an idea of your BF%. Because the absolute error of BIA and Bod Pod is similar, you’d be best off splurging and going to a more accurate testing method (DEXA) if you want pinpoint BF%. To me, it’s just not worth it of all the reason Ray covered in the summary Part II....
    Martin S. Newbury RC
  • Max Bridges
    Max Bridges Posts: 108
    The problem with these scales is they only measure the fat in the lower body not the whole body, the charge does not go to the top of the body only the legs. Also it is all based on averages for age etc. if you put in a different age you get a different result. If you squat on the scales you get a different result to standing. Tell the scales you are a woman and you get a higher fat reading.

    They are only any good for seeing trends up or down.
  • slunker
    slunker Posts: 346
    I tried a little experement with my home scale that "measure" body fat. I'm 5' 10" and 72kg and it says I have 23% body fat which I think was a high reading. So I stepped on the scales with 2 6kg dumbells and it said my percentage of fat was now over 30% so obviously its just a calculation they run and don't send any electrical current in to your system.

    Best method I have found is trouser belt and a mirror.

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