Body fat percentage

So what is my body fat percentage inquiring minds would like to know?…including myself…well sort of…the idea that the tests are all inaccurate…just to what degree…doesn’t really excite me very much, so I haven’t bothered.  I also have the opposite problem of a lot of people…I _think_ that I look good no matter what I _really_ look like 🙂

Here’s an interesting link that shows the progression in how a body looks as the body fat percentage comes down: http://www.exer-phys-club.com/bfguidearticle.html 

To me, 2 tests are as good as anything else out there:

  1. Mirror Test: jump up and down in front of the mirror and see how much jiggles…that’s the fat
  2. Speedo Test: how much do I need to suck in my gut in my Speedo on the pool deck to look passable

…and whatever you do _never_ stand next to David Quick in his Speedo…I only made that mistake once, and went on a diet for a month

Tons of stuff on the Internet about the different way to calculate your body fat percentage…as well as the weaknesses with each one.   One worthy of note is a newer test that may be worthwhile if you _really_ want to know:

DEXA (dual energy X-ray absorptiometry) (DXA)

This test is used to measure bone density, but it also measures body fat percentage as well as where most of your fat is (as if you didn’t know). The facts about DEXA:

  • DEXA uses a whole body scanner and two different low-dose x-rays to read bone mass and soft tissue mass.
  • It takes about 10-20 minutes to do a body scan
  • It provides a high degree of precision with a 2-3 % margin of error.
  • This is considered a gold standard for measuring body fat and bone density
  • It’s painless

So for purposes of this Post, I figured I’d go over to the local gym where I’m a member, and see if they could do a skin fold caliper test.

It’s a popular test, but even if the measurements are accurate, the skin fold caliper test has a wide range of inaccuracy…20% in an accurate test could really be anything from 16-24%…the value of the test is deemed to come from comparative results over time, using the same experienced technician, that at least tells you what the trend of measurements is.

They were very accommodating…after finding the calipers, and someone who had used them before, and then found the book that showed how and where to take the readings…true story…we proceeded with the 7 measurement test.  It had been a while since the technician had done a skin fold caliper test, acknowledged that the results therefore, may not be entirely accurate…had a challenge in getting the thigh measurement (a common difficulty)…and the manual calculations appeared to be very complex mathematical equations taken out to about 10 decimal points…but we did get a final number…27.8% body fat apparently.

When I got home I checked the math on the formula sheet, and there was a calculation error, so the measurements actually produced a 23.7% with the 7 measurements, or a 20.9%, if you used their 3 measurement formula, or a 20.1%, using an online YMCA calculator that uses a slightly different formula.
http://www.gain-weight-muscle-fast.com/body-fat-calculator.html
http://www.health-calc.com/body-composition/skinfold-ymca

I’ve also read that age adjustments in formulas…like the 3 that were used above…can also overstate the body fat in athletes:

Why do the equations include age? By including age the equations attempt to compensate for the fact that as your body ages it begins to lose lean muscle, retain intra-abdominal fat, and lose bone density. These things are not measurable with your body fat calipers. The age compensation included within the equations is based on normal people, not active trainers. Physical activity and especially strength training will negate the age part of the equation.So, if you are in superior shape you will likely get a more accurate body fat percentage by just claiming to be 20 (or 21 if you still want to buy alcohol) when you do your body fat calculations.

So plugging in 20 years old, instead of 56 into the formula, gives a 15.9% body fat.

So given the probable variance in the measurements to start with, and the variance in formulas, I still don’t really know what my body fat percentage is…about what I expected.  Male pro triathlete’s are 5-12%…I’ve seen those buff young guys, and I know that I’m nowhere near any of that.

I’m left thinking…

Matt Fitzgerald in Racing Weight, says that most endurance athlete’s are genetically capable of reaching at least the 80th percentile for their gender and age group as defined by data collected by Kip Russo, founder of Body Fat Test, Inc..  I’d be leaner than 8 out of 10 in the reference group, which was a group leaner than the general population to start with. 

For my age category…this would be 17.9%…sounds reasonable to me.  The next 2 levels are 85th percentile: 16.9%, and 90th percentile is 15.3%.

For Daughter: 80th percentile: 17.1%, 85th percentile: 16.0%, 90th percentile: 14.5%

Mirror Test, Speedo Test…and even with all the variables, the skin fold caliper test…there was stuff to ‘pinch’…all confirm about the same thing…I could probably lose 10 pounds anyway… and be better off for it.

…hopefully mostly fat…many authors like Ingrid Loos Miller in Weight Management for Triathlete’s say ‘losing some muscle is unavoidable during weight loss’…see our post on Losing fat not muscle.  At that point, I’ll probably do the DEXA test to see where I’m really at, and go from there.

…and even then, I still wouldn’t stand near David in his Speedo 🙂

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2 Responses to Body fat percentage

  1. Anne Boone says:

    I have a scale that supposedly measures body fat, but you have to plug in whether you’re athletic or sedentary. It makes a big difference in the results, so that doesn’t doesn’t sound very accurate. 25 years ago, when I was in great shape and weighed about the same as I do now, I had my fat measured at a lab with underwater weighing. I think it was about 18%. I KNOW I’m nowhere that low now. Basically, I know I need to lose fat. I can look at the pics of me in my wetsuit and see that!

  2. Dad says:

    Anne, my experience with those body fat scales are not good. I have an Omron scale with the body fat thing, and it has me currently at 44%

    I know that I’m carrying a few extra pounds, but not that much :)…I used a handheld tester the other day and it put me at 28.2%…the only good thing that I’ve read is that the readings can be consistent, so although not the right number, gives you an idea of whether you’re going up or down…feels rather useless to me though.

    The DEXA test sounded cool…and you get a bone density test at the same time…so might be covered by insurance…in reading seems it’s about a $200 test otherwise (unverified), so not horrible.

    I’m with you on the wetsuit thing…I’m sure that those wetsuit pictures add at least 10 pounds.

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