Help me find a reliable body fat scale?

  • Squarejaw

    Posts: 1035

    Oct 07, 2007 5:39 PM GMT
    I'd like a reliable bodyfat scale. I'd like it be accurate, but it seems a lot of them aren't. I'd be happy, though, if it were simply able to register changes in my body fat so I could track my progress. (In others, it would suck if the reading were always 7% too high, but as long as it was consistent, at least I could still see changes).

    I see some that are step-on scales, like Tanita BF680W, Tanita BC554, and some are hand-held monitors meant to be used with a separate scale, like Omron HBF-306C (all of these are on Amazon).

    I see different features, like measurements for bodywater and visceral fat, and setting like athletic vs. adult.

    But no one seems thrilled with a the bodyfat results. Does anyone have any experience with product like these, and the best way to use them?
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    Oct 07, 2007 5:52 PM GMT
    I have a Soehnle scale, and its body fat readings can vary 10 percentage points from one day to the next. I've read on RJ that the handheld units vary less in their readings than the scales, but I've come to the conclusion that electronic bodyfat measurement is too inaccurate to be of any use.
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    Oct 08, 2007 3:06 AM GMT
    Tanita BC-534
    Although there doesn't seem to be excessive variation from one day to the next, it certainly isn't very accurate. (Believe me, my body fat is higher than 6 percent!)

    I agree with Paradox that electronic body fat measurement is generally inaccurate, but I think it can be useful for observing trends over time. I've gained more than 20 pound since May, and it's comforting to know that my body fat percentage has remained about the same.
  • Squarejaw

    Posts: 1035

    Oct 08, 2007 3:10 AM GMT
    Thanks, Dean, though keep in mind that if you're gaining muscle weight while your quantity of body fat remains the same, then your bodyfat % should go down. Makes me wonder if the Tanita might just be giving you the same number over and over as a glitch.
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    Oct 08, 2007 3:20 AM GMT
    The best way for you to really accomplish this is to buy a set of body fat calipers, and have a friend take reliable, consistent measurements for you.

    Body-fat scales only calculate a change in voltage between the electrodes you are standing on. That figure is then used to calculate total body water. The water value can then be used to infer total body fat based on a manufacturer-supplied formula that considers the subject's age, gender, height and weight.

    A study by the NIH found that impedance measurements made by six different scales varied by as much as 40% from the actual impedance of a known standard.

    The study concluded that some instruments are sensitive to differences in skin impedance, which the devices are not designed to consider, resulting in inaccurate readings. Furthermore, readings are affected by numerous variables not considered in the algorithms the devices carry in their software. Some of these include body position during testing, hydration status, recent consumption of food and beverages, ambient air and skin temperatures, and recent physical activity.

    I wouldn't trust them. My scale tells me I'm 7% one day (somewhat close to my true number) and 12% the next day. That doesn't seem like a big jump numerically, but I doubt I got 71% fatter overnight.
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    Oct 08, 2007 3:21 AM GMT
    Hi Squarejaw, It does vary day to day, but you're absolutely right... the trend should be downward rather than level. My chest is bigger, my arms are bigger, my legs are bigger, and my middle measures about the same... so it seems like I should have a lower body fat reading. The manual says to take measurements 3 hours after you've stopped eating and drinking for the day -- but I have a hard time doing that, especially when I'm trying to eat enough to support muscle growth.
  • MikemikeMike

    Posts: 6932

    Oct 08, 2007 4:44 AM GMT
    My boy has a Tanita BF-681W. I think the weight is accurate, but the amount of calories it said I should eat is very high. icon_eek.gif All electronic BF scales are off. True body fat is best determined on an empty stomach and not right after drinking fluids and get dunked under water-called Hydrostatic!
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    Oct 08, 2007 5:37 AM GMT
    Honestly, most methods of measuring bf% or invalid and unreliable. Everything is either an indirect method (DEXA, densitometry, etc) or doubly indirect (anthropometry using calipers, bioimpedence,etc).

    On top of that, body fat equations were developed for group rather than individual assessments (and a standard error of estimate of 3.7% body fat...so you're looking at a plus/minus of 3.7 from the result that you're given). Bioimpedence is no better. Like others have suggested, it's really a measurement of your hydration levels based on the speed of conduction in your body. Those body fat scales also are based on an algorithm/body fat equation. So it's standard error of estimate is greater, around plus/minus 5%.

    Basically, equations are more valid relative to body fat scales but u have to take into account measurer error (rectified by taking the median of three skinfold measures). I probably didn't really respond to the original question..but i had to vent :-p sorry..haha