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Body Fat % Machines

chloeobe
chloeobe Posts: 72
in Fitness and Exercise
Hi,

I was recently given a fitness test at the gym by a "qualified" PT. He used a small handheld machine to calculate my body fat %, and it was 29%...I was shocked by this and he said I should be concenred that it was so high.

However what is baffling me is that I cant see how this can be accurate! Im 5"3 and 108 pounds with a BMI of 19.84. My measurements are as follows:

Bust: 32"
Waist: 24"
Hips (at widest part) 36"
Widest point of thigh 19"
upper arm 9"

Is this body fat % true or is it bull? Any help here would be greatly appreciated

Replies

  • kirk_clawson
    kirk_clawson Posts: 36 Member
    The handheld machine - were they calipers? (i.e. was he measuring skinfolds), or are you talking about an electro-static device that you hold for a few seconds then it gives you a number?

    If it was one of the electrical devices, then realize that those measurements are extremely sensitive to your hydration levels, sodium intake, and perspiration.

    Btw, according to the little card that came with my body fat measuring device, 29% puts you at the high end of the "Normal" range for a female your age (assuming your profile age is accurate). The normal range for female 20-39 is 21%-32.9%.

    Of course, the reference card could be wrong, but Wikipedia also puts 29% in the "Average" range.
  • chloeobe
    chloeobe Posts: 72
    No the machine was one of these

    http://www.bing.com/images/search?q=body+fat+percentage+machine&FORM=HDRSC2#view=detail&id=D72F5FF90E7D9174F50F9758759D9BA271E1AA88&selectedIndex=0

    Thanks, according to his chart 30% was "overfat" so I had to be careful, and reduce the % to around 20%!
  • tomcornhole
    tomcornhole Posts: 1,084 Member
    One data point is meaningless. Even the gold standard measuring methods (hydrostatic, DEXA and BodPod) are variable. And one data point from one method is not reliable at all.

    There are many ways to measure body fat %. Do them all and then track them over time. The trend is what's important. The absolute value will reveal itself over time.

    Methods that can be utilized:

    Mirror: compare to pics on web sites. This one is hard because it requires objectivity, but I have been able to nail my BF% to within 2% using this method. When I'm honest. When I'm not, I always guess 4% lower than what the BodPod says.

    Calipers: cheap set from Amazon are $8. You can do single or multiple point measurements yourself and use online calculators to determine BF%. This can vary a lot because of measuring technique, but many data points over time will average out the variability.

    Measurements: Measure your weight and waste and go here: http://www.foodcomputer.com/ComputeBodyFat.aspx or here: http://www.freedieting.com/tools/body_fat_calculator.htm. These are way off for some body types and way on for others. But data are data and you could track trends.

    BioImpedance thingies: scales or handheld. I have one and track BF% daily. It can vary a lot depending on how you use it and when. I just do it the same time each morning. It can vary +-5% throughout the day. Good for tracking trends.

    BodPod: I use this as truth data because they are convenient and close to my house. Probably as close to truth as you can get but they aren't perfect.

    Hydrostatic: gold standard other than DEXA. Never had one, so no comment on accuracy or convenience.

    DEXA scan: apparently truth data. Expensive and inconvenient.

    Try the top few that are easy to do at home. Track over time and then draw a line in all the dots. The more dots the better. Here's my data over the last year or so:

    BF20130527.png

    The red dots are the ones I trust the most as they come from the BodPod.
  • tomcornhole
    tomcornhole Posts: 1,084 Member
    No the machine was one of these

    http://www.bing.com/images/search?q=body+fat+percentage+machine&FORM=HDRSC2#view=detail&id=D72F5FF90E7D9174F50F9758759D9BA271E1AA88&selectedIndex=0

    Thanks, according to his chart 30% was "overfat" so I had to be careful, and reduce the % to around 20%!

    That's the one I use. I know my BF% is 15.6% from 2 recent BodPod visits. I can make my Omron say anywhere from 11% to 19% depending on how I hold it and when I take the measurement. It is good at tracking trends if you use it the exact same way/time/place every time you measure.
  • sam308lbs
    sam308lbs Posts: 1,936 Member
    This is a wild wild guess but if you have a little jiggle in each of your tummy,butt and thighs you are above 30 % bf.And if you have a little jiggle in just two of them,its still above 25 % bf in most cases.
  • kirk_clawson
    kirk_clawson Posts: 36 Member
    No the machine was one of these

    http://www.bing.com/images/search?q=body+fat+percentage+machine&FORM=HDRSC2#view=detail&id=D72F5FF90E7D9174F50F9758759D9BA271E1AA88&selectedIndex=0

    Thanks, according to his chart 30% was "overfat" so I had to be careful, and reduce the % to around 20%!

    That's the one I use as well. They aren't the most accurate measuring device to get a real number (like I said, they're very sensitive to your hydration level, what foods you eat, etc...), however, they are great for tracking a trend. That 29% may not be accurate, but if you measure again in a month (under the same conditions) and it says a lower number, you can be fairly confident that your body fat did indeed go down. That's all I use mine for.

    ETA: Here's a link to the study that my device's reference card was developed from, in case anyone wants to see the actual numbers:
    http://ajcn.nutrition.org/content/72/3/694.abstract

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