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Personal Scale w/ Body Fat Calculator - How Does It Work?

Discussion in 'Strength & Conditioning' started by Ol Timer, Dec 26, 2006.

  1. Ol Timer

    Ol Timer ↓ hog hunter ↓ Millennium Member

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    As one of my requested gift categories being affordable fitness equipment, I received a digital scale that calculates body fat percentage and water percentage.

    I plan on using this gift every day and am looking forward to monitoring my body fat, but don't understand how the scale calculates or determines it's findings.

    How does it work? Is it reasonably accurate? How often should I expect to see changes, good or bad?

    If this is just a gimmick, I would appreciate your honesty.

    Thanks for any input,
    OT
     
  2. DBradD

    DBradD

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    I have one of these. It works by sending an electrical signal through your feet and doing calcs based on the results of that signal. I don't know any more than that about how it works.

    They are somewhat difficult to use because the readings vary widely depending on your hydration level. Mine reads a solid 2% or more higher in the mornings than in the evenings, presumably for this reason. I think the best thing to do is take enough readings, maybe on in the morning and one at night, over a few weeks to notice a trend. I think they are in reasonable agreement with other methods although I only have one data point to make that conclusion. I had a test done using calipers and it gave similar results, off by a percent or two, IIRC.

    I think there was a thread in this forum about 6-8 months ago on this subject. It might have more info.
     

  3. ateamer

    ateamer NRA4EVR

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    Who cares what the bodyfat percentage is? If you're worried about being fat, base it on how you look, not what the numbers are. Of course, self-opinion based on physical traits should be based on performance, not looks. Muscles aren't for show, they are for use.
     
  4. DBradD

    DBradD

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    LOL ateamer! Haven't you been a little grouchy lately? :tongueout:

    For what it's worth, I care a little about approximate bodyfat percentage because I like to have some idea where that 10 lb came from (whether it's gained or lost).

    It's not my main parameter though, because if I gain 2% more bodyfat but I can run farther, faster, do more pullups, lift more weight, etc., I'd still consider myself to be better.

    Body composition is just another parameter that can be monitored.
     
  5. Ol Timer

    Ol Timer ↓ hog hunter ↓ Millennium Member

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    ateamer,

    I've never cared about body fat, but since I received this scale, I want to play with it and was curious how it works.

    I appreciate what you're saying about performance over looks. I'm not interested that much in either one. My goal is to beat the grim reaper a year or two by living healthy. If this scale can guide me in a positive direction, I'll use it.

    Brad,

    Thanks for the explanation and your personal findings.

    I'll see if a GT search turns up the previous thread.
     
  6. ateamer

    ateamer NRA4EVR

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    The grim reaper's a punk. Kick his rear end.:thumbsup:
     
  7. ryucasta

    ryucasta IDPA/IPSC Cuban

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    I currently have two of the Tanita scales and I have found them to be useful as a starting point for determining the percentage of fat in your body. The only caveat that I would give you is that its best to not weigh yourself after waking up since you body will be dehydrated at that time and that could cause the numbers to be off.
     
  8. malkore

    malkore

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    pretty much everything that's been said already is true. I know a little about fitness, how these scales work, and their weak points.
    hydration is a big one.

    but this sort of testing method, even when done 100% correctly with proper hydration, is still only accurate within 4%. it is accurate to itself though, so you're right that you can use these to track trends...useful since those resolutions are about 6 days away from being made ;)

    underwater hydrostatic bodyfat testing is more accurate. there's also a really cool one called a DEXA scan. its kinda like an MRI machine, so its harder to find places that can do it.
     
  9. DBradD

    DBradD

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    By 4%, you mean 4% of the measured value, right?

    For example, say it reads out 10%. +/-4% means that the actual reading is somewhere between 9.6% and 10.4% (NOT between 6% and 14%), right?

    If so, then I'd consider that to be extremely accurate. Most of the theoretical predictions we do in engineering are off by far more than that. My current vibration procedure is good only to about +/- 40-50% and there's nothing (that we have found yet) that's any better.

    DBD
     
  10. malkore

    malkore

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    Brad,

    nope, if it said 10%, you could be anywhere from 6% to 14% bodyfat.

    skinfold tests are usually about 1% (9%-11% using above example) if the tester is experienced.

    a dexa scan is absolutely accurate.
     
  11. DBradD

    DBradD

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    How sure are you of this? That would make the device almost totally worthless. Also, I know there's a difference between accuracy and precision, so which is off? If we're talking about unbiased random errors, then I would expect the scale to read very differently if I step onto it several times in a row. Consecutive readings are very consistent.
     
  12. California Jack

    California Jack Millennium Member

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    Sounds like it is accurate than. I do remember right, don't I?
     
  13. California Jack

    California Jack Millennium Member

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    Maybe I'm just getting old, but I hear a lot of talk here about looks and performance. That's all well and good, but what about health? I'd be more interested in blood pressure and good cholesterhol profile of bodyfat percentage.
     
  14. DBradD

    DBradD

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    That's a good point about blood pressure and cholesterol. Definitely more important than bodyfat percentage. Nowhere near as easy (or fun!?) to check, though.

    Right or wrong, I think of bodyfat as a secondary parameter behind performance. For example, I've gained 15 lb since April and I wanted to have some idea whether the extra weight was fat or muscle. I was able to approximate the increase in lean body mass.

    ateamer also brought up a good point that the mirror test is better than numerical values.
     
  15. California Jack

    California Jack Millennium Member

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    Yeah, I use the mirror test too, although my prefered test is the jeans method.