huge bodyfat test discrepancies

[liftnlady]

Today I had a hydrostatic bodyfat test (the water test) done for the first time. Based on caliper tests I had done a few months ago, I was hoping for a result in the range of 20-22% bodyfat. I was really shocked when the result came back at 12.3%! Now I don't know which numbers to believe.

I never had caliper tests done until a few months ago. The first results were disappointing to me (27.83%) as I'd been working hard in the gym for a long time and my diet was okay; it was not super clean but not horrible either. I was eating a lot of processed food and sugar though.

After that disappointing result I went on a much stricter and cleaner diet and bumped up the protein a lot. I trained a bit harder as well. Then I had the calipers redone a month and a half later and had lost a couple percentage points (down to 25.79%). The picture in my avatar was taken around the time of that last caliper result.

Since that time I have continued to eat much cleaner than I used to.

So then today I get that 12.3%. I still look about the way my avatar looks now, maybe a little leaner.

To recap:
5/3/08 with caliper (11 points): 27.83%
6/10/08 with caliper (same points): 25.79%
8/16/08 hydrostatic test: 12.3%

Are these number possibly true? Could changing my diet have made that much of a difference in the bodyfat percentage?

[Chopsta]

To my knowledge the hydrostatic is the most accurate.
In reality it doesn't matter all that much as long as you see your body making the changes you want, right?
If you're using the body fat measurments to track your progress stick with one method as at the very least it should be consistent.
Otherwise you could average out all 3 of the readings to capture the most accurate number.

[Primol]

Some people hold more fat in some areas more than average. This can skew the results. Also, the person doing the caliper reading might not know what they are doing.

[152_pilot]

hydrostatic is supposed to have something like a .5% margin of error; it is far more reliable than any of the caliper methods

[Nara62629]

hydrostatic is the most accurate way. and looking at those pics...there is no way you are 25% bf. just goes to show how off the calipers can be, or that whoever was doing it, was doing it wrong.

[JakeEdwin]

Originally Posted by Nara62629

there is no way you are 25% bf.

agreed no way in hell youre 25%

[eg2jdm]

Like the others said, hydrostatic body fat testing has an accuracy rating of <4%. So its a good way to measure true fat %'s. The caliper test is really subject to the assessor as there are numerous ways he/she can cause error in the readings. Also I would like to point out that what Primol was saying is also true. Not everyone holds their fat storage in the same places. The way the tests are calibrated are accepted based on the "majority" of people, not necessarily a particular individual so take it with a grain of salt...

[Tiffany_P]

Wow, that's a crazy difference. The hydrostatic test is pretty accurate, but it's possible that you have very good bone density, which can underestimate your %. For what it's worth, I would've guessed that you were around 16% from the pictures. 12% is pretty unhealthy for a woman. I'm pretty sure 12% is shredded. Who knows? The only way to know for sure would be to get a DEXA scan.

[liftnlady]

Originally Posted by Chopsta

To my knowledge the hydrostatic is the most accurate.
In reality it doesn't matter all that much as long as you see your body making the changes you want, right?
If you're using the body fat measurments to track your progress stick with one method as at the very least it should be consistent.
Otherwise you could average out all 3 of the readings to capture the most accurate number.

I guess that it doesn't matter, I was just curious more than anything when I started getting the measurements done. But I did put stock in that first high number and now I'm really questioning it.

When I was given that first number of around 28% by a trainer at my gym, I was also told I was in the overweight range. I took the trainer's information as being correct because I figured he knew what he was doing. I did have some friends at the gym say there was no way that could be right, but I carry most of my fat between my waist and knees so I just figured they couldn't see it.

Originally Posted by Nara62629

hydrostatic is the most accurate way. and looking at those pics...there is no way you are 25% bf. just goes to show how off the calipers can be, or that whoever was doing it, was doing it wrong.

Originally Posted by Primol

Some people hold more fat in some areas more than average. This can skew the results. Also, the person doing the caliper reading might not know what they are doing.

Originally Posted by eg2jdm

Like the others said, hydrostatic body fat testing has an accuracy rating of <4%. So its a good way to measure true fat %'s. The caliper test is really subject to the assessor as there are numerous ways he/she can cause error in the readings. Also I would like to point out that what Primol was saying is also true. Not everyone holds their fat storage in the same places. The way the tests are calibrated are accepted based on the "majority" of people, not necessarily a particular individual so take it with a grain of salt...

This is what I'm wondering, if he knew what he was doing.

Originally Posted by Tiffany_P

Wow, that's a crazy difference. The hydrostatic test is pretty accurate, but it's possible that you have very good bone density, which can underestimate your %. For what it's worth, I would've guessed that you were around 16% from the pictures. 12% is pretty unhealthy for a woman. I'm pretty sure 12% is shredded. Who knows? The only way to know for sure would be to get a DEXA scan.

12% is a scary number to me, especially since my goal was just to get down to 20% from what I thought was 25% (!), just to be in the healthy range. My arms are really vascular now but I still do have some fat around my thighs and butt.


I attached a few pics from today. In the end, I don't know if it's the actual number that matters, but what I did learn from this is that it's true what everyone says about trusting the numbers less and the mirror more. I was getting freaked out lately about how vascular my arms were and whenever I'd see pics of my face it looked too skinny. The b/f% numbers I was given before were way high to me though so I wasn't trusting my own judgment.

In the pics from today I think my arm and upper body looks 12% but my lower body looks much higher. So, who knows?

[Kilim]

Dexa is the most accurate test followed by Hydro Weighing.
BIA and Caliper test is next due to the discrepencies you can get.
BIA has around 4% Margin of error.
Calipers margin of error is dependent on the person using it.
Even a VERY trained Caliper Person can still yield a margin of error.

Here is some nice articles about it:
http://mb-soft.com/public2/bodyfat.html

http://www.martinrothonline.com/pers...tors_guide.htm

http://www.womens-health-fitness.com...analyzers.html

Right now I have a Caliper, the handheld Omron and a Life Fitness BIA Scale.
All 3 give me different readings with the Omron giving me the lowest reading at this time.

Pretty much now I just use them as a guide for daily/weekly checks as its cheaper than doing the DEXA/hydro Weighing for a daily/weekly checks.
but I guess it don't hurt to do the DEXA/Hydro Weighing every now and then if you can find a place for it and the money.

[liftnlady]

Originally Posted by Kilim

Dexa is the most accurate test followed by Hydro Weighing.
BIA and Caliper test is next due to the discrepencies you can get.
BIA has around 4% Margin of error.
Calipers margin of error is dependent on the person using it.
Even a VERY trained Caliper Person can still yield a margin of error.

Here is some nice articles about it:
http://mb-soft.com/public2/bodyfat.html

http://www.martinrothonline.com/pers...tors_guide.htm

http://www.womens-health-fitness.com...analyzers.html

Right now I have a Caliper, the handheld Omron and a Life Fitness BIA Scale.
All 3 give me different readings with the Omron giving me the lowest reading at this time.

Pretty much now I just use them as a guide for daily/weekly checks as its cheaper than doing the DEXA/hydro Weighing for a daily/weekly checks.
but I guess it don't hurt to do the DEXA/Hydro Weighing every now and then if you can find a place for it and the money.

I never heard of the DEXA test until today. It's probably worth it to do what you're doing and learn to test myself with something cheaper just to see trends and then do the hydro test once in a while. I don't think I'll have the trainers do it any more...

Thanks for the links!

[Kilim]

If I can do DEXA and Hydro Weighing for cheap, I would do it often.
hell I have never done it but would love to so I can get an accurate reading

[liftnlady]

Originally Posted by Kilim

If I can do DEXA and Hydro Weighing for cheap, I would do it often.
hell I have never done it but would love to so I can get an accurate reading

I paid $49 today to have the hydro done and I'm still not sure it's accurate, lol. It was also very scary to do, not something I would pay $49 to do on a regular basis. Maybe once or twice a year!

I thought I'd just lie back in a tub of water for the test, but I actually had to breathe all the air out of my lungs while completely underwater three separate times. I had a horrible headache after that was over!

I read about calipers in the first article you linked and it said the margin of error can be 10-15% in general, and 10% even with skilled testers doing it. So that does help explain the discrepancies. Very informative articles, thanks again.

[matsimitso]

Ur not 12% , 12% on a women is shredded! like 7% on a guy.

But ur not 12% either.. i'd guess 18 or somthing.

[liftnlady]

Originally Posted by matsimitso

Ur not 12% , 12% on a women is shredded! like 7% on a guy.

But ur not 12% either.. i'd guess 18 or somthing.

I really don't think so either. I told the guy who did the test that there was no way I was that low but he insisted on the accuracy of the test.

I'm guessing 18-20% is probably about right. I did the Navy tape measure test earlier in the week for comparison purposes and it said around 20%. It's a free test, easy to do at home yourself, and may have been the most accurate of them all.

[Nara62629]

i'd believe the hydrostatic test...look at the vascularity! i mean yes generally they say women hold more bf than men, but we're talking about you, not "most women". from the pics i've seen, you are not 20% not even close. look at your arms, even your abs. u look pretty lean to me...like a mid distance runner...and i think they are right around 10%. See Kara Goucher...