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Accuracy of scales that measure % body fat


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Just wondering if anyone has a scale that measures body composition (% body fat).  I have one at home and I am uncertain of its accuracy.  I don't know how accurate they are in general.  I usually read 33% (which makes me wanna be ill!) but have recently been reading 28% (been working out hard!).  Does anyone know the margin of error on these things?  I thought women (I'm 5ft 3") were supposed to be 20-25% - needless to say I'm unhappy with the current reading on my scale!  Ideas?

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Scales are only moderately accurate readers of body fat. For one thing, they are highly dependent on your hydration. Alcohol and heavy exercise or sweating—dehydration issues—can throw off the scale. Skin temperature can also adversely affect the results of body fat scales, by affecting the electrical current the scale generates.

What makes these puppies work is that the signal travels faster through water. Because muscle is largely water, and fat contains little water, the scale is able to make a distinction and give you a reasonable estimate. But you can see from how it works how important hydration is to the equation.

Also, I find that mine is somewhat accurate only if I place in on the "athlete" setting. I am well under 20% body fat, and on that setting the scale tells me this, although it still isn't 100% accurate. If I set it on "regular," though, it estimates my body-fat percentage significantly higher than it is.

#2  
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My scale doesn't differentiate body types.  It simply allows you to input gender, adult/child, and height.  I'm hoping that means my scale is inaccurate.

I've heard they can be as much as 10-20 % off so you might want to try other methods of getting it checked and compare.  If they are all close it might be accurate.


I bought a set of digital calipers and a vinyl measuring tape for getting measurements(there are sites that you put in the measurements and get a body fat % from that not sure of a good one though I've heard some are inaccurate) and a set of regular non digital for 32.00 including shipping from amazon


I'm gonna check with those and see if I get something different than my digital scale which also gives me 37%.

I've heard calipers are more accurate and I think measurements can be too though I'm not absolutely certain.  Since they weren't all that expensive though I figured I'd check it out and see if the numbers were all different or close and than go research which one is more accurate.

My scale also does not ask for body type(atheletic etc....)is that a Tanita?  I've heard those are some of the better scales.

I have a Weight Watcher one and it gives me a different weight everytime I step on it so I bought an Analog Dial scale ....which seems more accurate, but I can't see it while standing on it if its not on one of the big numbers....:(

 

I have a set which im pretty sure are fairly inaccurate ... however i still use them quite frequently.

I used them at the same time of day eat time so its consistant as possible and although i don't hod much faith in the number its read's i do watch the trend ... today it says im at 23.5% body fat, this time last week it read 24% body fat and the week before it said 25% body fat ...

I know they numbers are wrong but im hoping the fact that the number is still dropping means that im doing myself some good and it means the reason my scales (weight wise) arn't moving down is because im turning fat to muscle if nothing else.

right now its all i have to cling too. So leave me blissfully ignorant with my very inacurate body fat readings.

Original Post by raiken3712:

 

My scale also does not ask for body type(atheletic etc....)is that a Tanita? I've heard those are some of the better scales.

 

It is a Tanita, yes. They are supposed to be the most accurate, though they have the same limitations as other scales in the end.

Calipers are generally more accurate.

Original Post by raiken3712:

I have a Weight Watcher one and it gives me a different weight everytime I step on it so I bought an Analog Dial scale ....which seems more accurate, but I can't see it while standing on it if its not on one of the big numbers....:(

I have two digital scales. Both are surprisingly rock steady when it comes to the numbers: if I step on and off over and over, the number doesn't change. But I have read that many people have a problem with fluctuating numbers.

Mine's a Tanita. Works wonderfully. Was within 1% of the measurement my trainer took with calipers and 2% of the measurement given when I did the one in a water tank at the gym (where they measure the displacement and calculate your fat based on your weight in and then out of water). Don't know how accurate the latter was. I've been told the calipers are the most accurate of the do-it-yourself methods. Short of going to a doctor and having a DEXA, you're not going to get a terribly precise measurement.

#8  
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Thanks for the info!  I think I"ll set up an appointment to have a caliper test done by a trainer at my gym.  Sounds like fun - pinching the fat with a stranger!  Good times.  At least it will let me know how accurate the scale is.  Maybe my nx scale will be a Tanita.

Pay $5-10 to go to a gym and get a legitimate test done once or twice a month.  Those scales have little accuracy nor precision.  The best test I've seen requires submerging you in a pool.

My understanding is that the percentage that the scales tell you will vary by your hydration (mine varies by about 4% depending on how much water I drank that day).  While the scales might not be accurate, they are precise (I'm getting high school chemistry class flashbacks ... ).  So, you might not be getting your true body fat percentage value, but you will be able to measure your progress. 

For example, less than two years ago my scale measured me between 17 and 19 percent body fat.  I started working out more and eating less and better.  Now it ranges from 10.5 to 14 percent.  Those probably aren't my actual numbers, but I know I'm doing a lot better than I was...and that's good enough for me.

my "homedics, the personal trainer, health station" scale also differentiates between "athlete" and "normal."  i'm never sure which one i should be using.  i know petite_powerhouse recommends, the "athlete" setting, but it's almost a 10% difference, which makes it seem like an important decision.  i'm 14.7%body fat or 24%, depending on the setting.

as for calipers, the results are only as accurate as the person performing the test.  i used to get mine done at the gym too, until i got wildly different numbers every month and then gave up. 

Original Post by caloriecountingme:

my "homedics, the personal trainer, health station" scale also differentiates between "athlete" and "normal." i'm never sure which one i should be using. i know petite_powerhouse recommends, the "athlete" setting, but it's almost a 10% difference, which makes it seem like an important decision. i'm 14.7%body fat or 24%, depending on the setting.

as for calipers, the results are only as accurate as the person performing the test. i used to get mine done at the gym too, until i got wildly different numbers every month and then gave up.

Do you still have the instruction manual? It should differentiate the two settings for you. You might even be able to find it online.

Here's what it says about Tanita online:

"Tanita's 'athlete' is someone who gets about 10 hours a week of intense physical activity (this can be exercise, work or leisure related.) 'Athletes' also have a resting heart rate of about 60 beats per minute or less. This mode includes people who have been very fit for years but currently exercise less than 10 hours per week. It does not include 'enthusiastic beginners' who recently started making a real commitment to exercising at least 10 hours per week but whose bodies have not yet changed to qualify for the Athlete mode."

My scale settings don't differ by 9%. It's about a 6% difference. I don't know how accurate that one is compared to the Tanita. I'm not familiar with it. 14.7% is quite low—at a level where your cycle can stop even, I believe, although it is still within the range for a professional female athlete—but these scales aren't 100% accurate, either.

Mine reads just a bit higher than that, and it's pretty close to what the calipers and other measurements tell me. I'd say get tested with the calipers and then you'll know which setting to use, even if the scale isn't completely accurate. I can't judge body fat, because if I were judging my own, I'd guess much higher than it really is. I was shocked the first time I got real tests done.

my manual says athlete's for 12hrs of cardiovascular activity.  i do enough cardio to make the "athlete" cut.  but i see plenty of overweight people on treadmills every day, so i really don't understand why it measures so differently. 

the first caliper reading was 26%, then it decreased but would vary.  one reading would be like 24% or 22% or 17% or 15%.  it was annoying.  this was all w/in like 3 months, and i know i didn't lose that much fat in that time (i still weigh the same, minus about 5lbs).

Original Post by caloriecountingme:

my manual says athlete's for 12hrs of cardiovascular activity. i do enough cardio to make the "athlete" cut. but i see plenty of overweight people on treadmills every day, so i really don't understand why it measures so differently.

the first caliper reading was 26%, then it decreased but would vary. one reading would be like 24% or 22% or 17% or 15%. it was annoying. this was all w/in like 3 months, and i know i didn't lose that much fat in that time (i still weigh the same, minus about 5lbs).

Oh, right: you mentioned the problems with the calipers. I used the calipers, but also the water test to find out what my percentage was.

As for the different modes, it has to do with the algorithms used. The algorithm used for someone who works out as much as is required for Athlete mode factors in the greater muscle mass and lower hydration level expected of athletes. Because muscle is largely water and fat is most certainly not, the results would be skewed to give you a higher body-fat reading were the algorithm not adjusted.

As far as overweight people go on treadmills, here is what Tanita says about that:

"Tanita's athlete definition includes "lifetime of fitness" individuals who have been fit for years but currently exercise less than 10 hours per week. Tanita's athlete definition does not include "enthusiastic beginners" who are making a real commitment to exercising at least 10 hours per week but whose bodies have not yet changed to require the Athlete mode."

 

thanks, petite-powerhouse.  though i don't believe my body will ever truly fit that of the average athlete, i think it's probably been accustomed to my activity level long enough that it's adjusted muscle mass and hydration levels accordingly.  at least i feel legit in using the athlete mode; i guess since i tend to have more fat than the average athlete, though, i can't take the numbers to heart (maybe i should average the two).

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