Accuracy of BF% scales?

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wilsonunc
wilsonunc Posts: 45 Member
in Health and Weight Loss
I was just wondering: how accurate do you think the body fat percentage scales are?
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  • davert123
    davert123 Posts: 1,568 Member
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    not very at all. They measure resistance and there are loads of factors that will change your resistance - such as the amount of water you have inside you, if are sweaty etc. I think they may have a use of measuring a trend as long as you weight yourself at the same time, with the same hydration and not after doing exercise etc but I think you would be comparing a something relative and not that accurate. I am sure it could show you that you are going in the right direction after a few weeks though :-)
  • 7aneena
    7aneena Posts: 146 Member
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    Yes what the above poster said, only thing it's good for is watching trend and even that is not very reliable.
    Just as an example, My scales gives me a reading that is 12% higher than my skin fold test :o
  • BinaryPulsar
    BinaryPulsar Posts: 8,927 Member
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    My husband is a physicist and he laughed very much, and made many jokes when I told him about the BF% scale at the gym. He said it's no better than a fortune telling machine at a carnival. The fact that you can get two different numbers by telling it your fitness level is also a clue to how silly they are.
  • DavePFJ
    DavePFJ Posts: 212 Member
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    I'm an engineer and they're completely accurate.
  • Elemielm
    Elemielm Posts: 1
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    DavePFJ wrote: »
    I'm an engineer and they're completely accurate.
    Trust him, he's an engineer !


    About the 'accuracy' : I had two scales , they gave me differents % of Body Fat .
    So i bought a third one .
    Now i have 3 differents % ....

    :neutral_face:

  • Liftng4Lis
    Liftng4Lis Posts: 15,150 Member
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    DavePFJ wrote: »
    I'm an engineer and they're completely accurate.
    Let me count the ways!
  • Go_Mizzou99
    Go_Mizzou99 Posts: 2,628 Member
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    I am a more experienced engineer...they are approximate.

    Also use the body fat web sites using measurements...they will vary by as much as 5% for me. Also approximate.

    Calipers are more accurate and precise.

    B) Your homework assignment for today is to understand the difference between precision and accuracy B)
  • Missjulesdid
    Missjulesdid Posts: 1,444 Member
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    They're not terribly accurate to determine your actual BF%, but they are directionally accurate. You need to take the measurement at the same time and under the same conditions (empty stomach empty bladder, time of day, etc). So it's not a great tool to tell you your exact BF%, but it will be able to tell you if you are gaining or losing bodyfat/lean mass.
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
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    DavePFJ wrote: »
    I'm an engineer and they're completely accurate.

    Mine can read 30% one minute and 60% the next. It's useless.

  • jim180155
    jim180155 Posts: 769 Member
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    Bioimpedance scales are the least accurate method of measuring bodyfat and may be off by as much as 5%, but none of the methods are 100% accurate. And bioimpedance scales are relatively inexpensive and make daily home measurements quick and easy.

    I bought a bioimpedance scale almost two years ago after I had already lost about 16 lbs. (I wish I had gotten one right at the very start.) Since then I have seen the readings drop from 22% to a low of just under 10%. Although the readings in my case are too low, the trend is real.

    A month ago I started using calipers for skinfold tests and a tape measure to plug measurements into an online bodyfat calculator. I now use four different bodyfat estimate methods on Saturday mornings and log the results. From yesterday:

    Bioimpedance scale: 11.4%
    Suprailiac 1 point with calipers: 14.6%
    Jackson-Pollack 3 point with calipers: 12.4%
    Tape measure: 11.6%

    Of all the methods, I think the Suprailiac test is probably giving me the most correct estimate.

    Note that calipers are not a good method of measuring bodyfat if you are obese. A bioimpedance scale will probably give better estimates if that's the case.

    Bioimpedance scales measure electrical resistance and are estimating the amount of water in your body given your height, weight and age. Lean body mass contains a lot of water. Fat does not. And water is an excellent electrical conductor. So the higher the resistance, the more fat is in your body. The readings will vary depending on your hydration levels; the more hydrated your body is, the more the scale will read as lean body mass.

    If you go with a bioimpedance scale, read the directions. You should find guidelines such as weighing yourself at the same time every day, preferably first thing in the morning just after peeing and before you eat or drink anything, which helps maintain consistent hydration levels.
  • DavePFJ
    DavePFJ Posts: 212 Member
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    I know for a fact that I'm 2% body fat just like my scale tells me. I dropped down from 35% body fat in 2 weeks.
  • Liftng4Lis
    Liftng4Lis Posts: 15,150 Member
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    DavePFJ wrote: »
    I know for a fact that I'm 2% body fat just like my scale tells me. I dropped down from 35% body fat in 2 weeks.
    I'm pretty sure 2% body fat would be impossible. How would your body protect your organs without any fat???
  • DavePFJ
    DavePFJ Posts: 212 Member
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    I have faith
  • ninerbuff
    ninerbuff Posts: 48,679 Member
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    wilsonunc wrote: »
    I was just wondering: how accurate do you think the body fat percentage scales are?
    They're not. Body fat is measured by biometric electrical impedance. Just drinking water will change the measurement since water is a better conductor. So the more hydrated you are, the lower the body fat reading and vice versa.

    A.C.E. Certified Personal and Group Fitness Trainer
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 30 years and have studied kinesiology and nutrition
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  • jim180155
    jim180155 Posts: 769 Member
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    A couple more thoughts:

    Although some of the others here seem to be getting different results, I found my bioimpedance scale to be pretty consistent. The results can vary from day to day, but it was rarely by more than 2%, so within that margin it was still good for measuring trends over time. And unlike the most accurate methods which are expensive and inconvenient, you can get daily readings to spot trends before they progress too far. FWIW, I use an Omron scale that measures through both your feet and hands: http://www.amazon.com/Omron-HBF-514C-Composition-Sensing-Monitor/dp/B0020MMCDE/ref=sr_1_1?ie=UTF8&qid=1413125075&sr=8-1&keywords=omron+hbf+514c

    Having said that, I think calipers give better results. They take a little longer, but can be far cheaper and you still have the advantages of being able to take daily readings without needing help from others. The calipers I bought: http://www.amazon.com/Accu-Measure-Fitness-3000-Personal-Tester/dp/B000G7YW74/ref=pd_bxgy_hpc_text_z
  • philwrightfitness
    philwrightfitness Posts: 122
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    Firstly remember that scales measure overall body fat and calipers only measure sub cutaneous fat. The point is they all use an algorithm based on average subjects and then the accuracy can be influenced by hydration and even the cleanliness of the contacts, . In the end to measure is better than not, but look at long term results and always be consistent with how and when you measure
  • nicoleagafitness
    nicoleagafitness Posts: 100 Member
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    Liftng4Lis wrote: »
    DavePFJ wrote: »
    I know for a fact that I'm 2% body fat just like my scale tells me. I dropped down from 35% body fat in 2 weeks.
    I'm pretty sure 2% body fat would be impossible. How would your body protect your organs without any fat???
    Is your sarcasm detector broken? lol
  • nicklippa
    nicklippa Posts: 31 Member
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    Please save your money and don't buy any! I have tried the Fitbit, Withings and even the more expensive one at the gym. They are all inconsistent and can screw up with your brain and motivation level. My body fat calculator is simple, I used to be a size 42 and now I am a size 34 waist. I tried on a pair of skinny jeans yesterday and they fit! I wouldn't be caught dead wearing them at 49 years old but they still fit.

    Who cares, how do you feel? How do your clothes fit? What is your energy level like? That is what matters. IMO!
  • jim180155
    jim180155 Posts: 769 Member
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    I almost forgot, this is the product I'm thinking about getting: http://www.skulpt.me/
  • llUndecidedll
    llUndecidedll Posts: 724 Member
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    I don't believe they're very accurate. Unless being at 5'6, 260 lbs, I really do have 38% body fat?? I don't think so.

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