Stupid fat-measuring bathroom scales

  • Posted by a hidden member.
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    Jul 31, 2008 6:12 PM GMT
    Why is it that it always seems I have considerably less fat after I showered? Like a good 1-2% gets knocked off after I've dried up. I guess my weight goes down a little in the process too; I suppose washing off all that sweat probably does that ...
  • MSUBioNerd

    Posts: 1813

    Jul 31, 2008 9:19 PM GMT
    Most bathroom scales which claim to measure your body fat percentage do so through measuring electrical impedence, on the basis that fat is basically an electrical resistor while water and many proteins are conductors. Showering will increase your water percentage, as you'll have both surface water on your skin and some diffusing into the skin itself, particularly if you had been sweating previously and thus were somewhat dehydrated. That will increase your overall conductivity, and thus most likely register as a lower body fat percentage.
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    Jul 31, 2008 9:36 PM GMT
    MSUBioNerd saidMost bathroom scales which claim to measure your body fat percentage do so through measuring electrical impedence, on the basis that fat is basically an electrical resistor while water and many proteins are conductors. Showering will increase your water percentage, as you'll have both surface water on your skin and some diffusing into the skin itself, particularly if you had been sweating previously and thus were somewhat dehydrated. That will increase your overall conductivity, and thus most likely register as a lower body fat percentage.


    So is the upshot of this that most bathroom scales which claim to measure body fat are inaccurate?
  • MSUBioNerd

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    Jul 31, 2008 9:45 PM GMT
    "So is the upshot of this that most bathroom scales which claim to measure body fat are inaccurate?"

    Yes. They do have a potential use, of course: while they may not be accurate, it's possible they are precise. If you use one at the same metabolic state each day, you can track trend lines. If you already have one of these devices, it might be a good idea to, say, measure yourself first thing every morning. Decide in advance what you might want to do before/after your measurement: do you take a drink of water first? Use the bathroom? etc., just be really, really consistent about it. Then, while the number on the screen might not be an exact indication of your true body fat percentage, changes in the number displayed are likely to measure true changes in you. To test that, try measuring yourself every 5 minutes for half an hour sometime when you're not sweating, showering, or consuming anything, and see if there are noticeable changes in the displayed value.
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    Jul 31, 2008 9:46 PM GMT
    It's prolly the earwax that you washed out.
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    Jul 31, 2008 10:05 PM GMT
    I've heard the only 'accurate' method to measure body fat percentage is by way of an underwater scale. I'm not sure why everybody stresses about this and that percentage, or this and that number.

    What it boils down to is: If you look thin, you look thin. If you look fat, you look fat. If you look muscular, you look muscular. icon_razz.gif Simple.
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    Jul 31, 2008 10:23 PM GMT
    Electric Body Fat thingy on Tonita body scales or something you might find at your gym that doesn't know how to do caliper testing are extremely inaccurate. Most need you to not eat 4 hours prior and not drink 2 hours prior to the test. Like it has been already said so many factors can inhibit good results. All it does is just send a pulse through your body and test the feedback and resistance it gets.

    To be honest, even calipers are off if used to calculate body-fat. While calipers are the most accurate to get a detailed reading of specific fat deposits in some locations, they formulae that are used are always different and lead to different results. There is one formula for normal weight people, overweight people, skinny people, healthy people, etc... up to 100 some different ways to read the results.

    The best way to test body fat % is through submersion testing unfortunately that is WAY TOO EXPENSIVE. Thus, the thing I always tell people is to get readings of 3-5 pinch zones on their body from calipers and monitor weight loss like that. Body Fat % means nothing, it is all about whether or not your fat deposits (for example) around your lower abdomen are getting smaller or bigger.
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    Jul 31, 2008 10:25 PM GMT
    KentuckyTuss saidI've heard the only 'accurate' method to measure body fat percentage is by way of an underwater scale. I'm not sure why everybody stresses about this and that percentage, or this and that number.


    Well, here's the issue. Unless the fat percentage is calculated by the underwater method, you'll note that you're always asked your age and level of activity. That's because these devices (and/or the programs that come along with them) add a certain amount to the impedence-derived fat % for visceral fat (fat around your organs, but not in the skin).

    The trouble with that is that the assumptions are based upon, essentially, actuarial statistics. In other words, suppose you are a ripped-out, toned 55 year old. If you use one of these devices, they will add an amount based upon the averages assumed for visceral fat for "active" 55 year old persons. Since the average 55 year old is "active" if he walks around the block once, you can see the problem.

    So I did a little experiement with the scale that I have. The thing measured my fat % as 18%! I recalibrated the thing for a 40 year old, and then a 30 year old, and got 13% and 10% respectively. Bull bleep!!

    It's not so much stress...it's wanting a measure that is comparative to other people.

    If you are measured underwater, your fat percentage is your fat percentage, and there will be no fudge factors added because of age.

    John
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    Aug 01, 2008 4:25 AM GMT
    Yeah, I'm trying to use this scale as a benchmark; more for precision as MSU has suggested it could be useful. Thing is, I've been consistently getting the same fat readings at the same time of day, before and after I run, etc. so I was just a bit frustrated when I wrote this post. I've never had a six-pack in my life, so it's a big venture for me and I'm doing all I can to get one. (I actually made another post that was a bit more constructive if anyone is interested: http://www.realjock.com/gayforums/247014/)
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    Aug 01, 2008 4:39 AM GMT
    I suggest people dump the silly Tanitas and the goofy calipers and forget the dunk tank. I have the most perfectly accurate body fat measurement device ever invented:

    166-6244932A67UC336693M.jpg

    Send me $59.95 and I'll tell you how to get one of your own.

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    Aug 01, 2008 4:49 AM GMT
    muchmorethanmuscle saidHey...

    I already made mention of the DEXA test. It's more accurate than underwater submersion.

    Nobody listens to me.


    sniffle....!


    Huh? Sorry, you broke up there.

    icon_smile.gif

    Hey Much, I often suffer from the "I posted exactly what he said way earlier and nobody noticed and now they're all about the guy that just repeated me" syndrome.

    This happens all the time and it has nothing to do with you. It has to do with the forum user interface and the the way it interacts with people's brains. Suffice it to say that many people read the top, then skip down to the bottom without reading the middle, cause the top few posts trigger a "hey, I have a response to that" response.

    My recommendation: if you find yourself pouting too much, it means you need a break from the forums icon_smile.gif I'm about due for one myself, as I've been posting like some jittery coffee-soaked forumbot lately.

    K
  • reload16

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    Aug 01, 2008 6:23 AM GMT
    muchmorethanmuscle said
    dr_jackl said

    However now there's a form of an x-ray called DEXA which stands for Dual Energy X-ray Absorptiometry. It's now becoming the new gold standard and you don't have to get wet and be in a cube like pool! But hey! I like to get wet!




    Yeah I heard that DEXA is the most accurate. It also scans the bone density I believe. I tried the underwater method but it was very uncomfortable to do and so the results weren't really good or accurate. But where can a person get the DEXA scan done? its probably expensive?
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    Aug 01, 2008 6:29 AM GMT
    My Weight watchers scale that is supposed to "electronically" measure my body fat is so freakin stupid. It says...acocrding to any chart you can find anywhere....standard one size fits all determination of body fat. It says I am 175 lbs with 21% body fat. I took a medical measurement of body fat ( a thing with bells and whistles....but accurate) PLUS I got the standard caliper measurement tool ( recommended by someone here on RJ). Both methods say I have 5% body fat. Go figure.
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    Aug 01, 2008 9:13 PM GMT
    muchmorethanmuscle said
    KissingPro saidMy Weight watchers scale that is supposed to "electronically" measure my body fat is so freakin stupid. It says...acocrding to any chart you can find anywhere....standard one size fits all determination of body fat. It says I am 175 lbs with 21% body fat. I took a medical measurement of body fat ( a thing with bells and whistles....but accurate) PLUS I got the standard caliper measurement tool ( recommended by someone here on RJ). Both methods say I have 5% body fat. Go figure.



    I'd like to see a picture of you at your 5% bodyfat. Bodybuilders are roughly 4% in contest shape. I high doubt you are that ripped naturally.


    And as far as DEXA scans.
    I would imagine that they are a bit pricey. Any new apparatus/toy in the medical community is so expensive in the beginning. It's like you gotta whore out your grandmother, mother and sisters in order to afford medical care these days.


    I'm ripped because of diet and exercise and an active healthy lifestyle ( I'm not sure I understand your statement). I am lucky in that I walk by weight machines and weights and I get bulky...so I have long ago switched to more ab work, cardio, stetching, cable work and flexibility stuff. I don't want to be big and although my muscles are pretty big all over. Over the past 18 months I've lost 55 lbs...naturally, a lot of the loss was fat, but I was also glad to loose some bulk muscle...I just don't like being bulked up so much.

    At my YMCA, you can pay 5 bucks and get the quick medical exam scan.

    OK, I lied.. so maybe the skin caliper measurment tool actually said 6% and the scan said almost 7%. lol