Bodyfat Experiment: Dexa and Hydrostatic Same Day
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CJ_Holmes
Posts: 759 Member
Thought this might be interesting for the numbers folks! I did both Dexa and Hydrostatic today. Dexa: 22%, Hydro 15%.
The dunk tank comes to our gym regularly and I always suspected it reads me low because of my solid bones. I’m currently on a modest cut trying to make weight for a lifting meet and then I’ll make new goals.
The dunk tank comes to our gym regularly and I always suspected it reads me low because of my solid bones. I’m currently on a modest cut trying to make weight for a lifting meet and then I’ll make new goals.
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Replies
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This is incredibly interesting, and I appreciate you posting it, as I'm sure others will. You have clearly worked hard, and look fantastic, btw.
Which of them did you personally think was closer? I found a page with some close examples, and I would say the 18% ladies look the closest, but it's hard to say, as none are a dead-on match.
https://www.google.com/search?q=women's+body+fat+percentage+pictures&oq=women's+body+fat+percentage+&aqs=chrome.3.0j69i57j0l2.12219j0j4&sourceid=chrome-mobile&ie=UTF-8#imgrc=dD9MIYYxVTbqGM:2 -
DXA always gives a higher result for me than Hydro. I've been doing both quarterly for over a year.
Last test results (done w/in 1 month of each other) were 13.4% DXA and 10.9% Hydro.
DXA gives more data than Hydro but I don't think one is more accurate than the other as far as the BF% is concerned.
When people ask what my BF% is, I give them the Hydro % because it's lower but, for data monitoring purposes, I just average the 2.
LOL!
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Athena98501 wrote: »This is incredibly interesting, and I appreciate you posting it, as I'm sure others will. You have clearly worked hard, and look fantastic, btw.
Which of them did you personally think was closer? I found a page with some close examples, and I would say the 18% ladies look the closest, but it's hard to say, as none are a dead-on match.
Thank you so much! When it comes down to it, it’s all interesting to me but there is probably no real answer. The whole Bay Area CrossFit community uses the same Hydrostatic guy, so we all have that as the reference point. Maybe I’ll tell CrossFitters I’m 15% and 20% to the rest of the world if anyone cares.
I think the most useful thing for me is to keep up with one method to keep track of progress. I know a lot of people wonder about bodyfat% and different testing methods so I hope posting this can give some perspective. The online pictures never help me much because I have a huge ribcage, no boobs, and a square body so I never look like any of them, lol!
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I thought it was also interesting their Lightly-Active estimate (did they even ask you about your life and exercise routine or just assume?) was 1.2 x RMR.
Now, considering RMR is higher than BMR by a bit, that may not be that off.
Then again, they don't say what formula they use for RMR from LBM.
Great results.
Do the hydro guys even mention, or perhaps have a label, as to when their stuff was calibrated last?
Like this shows, they may do it in front of the first person they weigh.
https://youtu.be/fOhHQylVbFk
Moving equipment in a truck makes me wonder if they don't do it, 22% probably more accurate.1 -
Wow, we could be DEXA twins!
I've got really, really similar fat distribution and BF% was slightly less than yours from my results (which was like 2 years ago so I think the BF% is a bit lower now) though I'm quite a bit older and weighed a lot less when it was taken.
I've read that DEXA is more accurate.
You've obviously worked very hard, going by your recomp progress.
Congratulations!!1 -
Thank you for sharing. I know nothing about bodyfat measurements, but I do know you look fantastic, keep up the great work 4
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Should have gone for the trifecta and had a caliper test on the same day, you know, for science
You look fantastic, by the way. I'm similar to you in height/weight, but your abs are much nicer!1 -
Love the comparison! I did a comparison between Dexa and Bodpod last year, but didn't have access to hydrostatic. Those results were actually very close. That's a pretty big difference between hydro and dexa. I agree that just picking one and tracking the change is most useful. You can see your steady decline in BF from your hydro history. You look amazing btw.1
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Interesting the differences in the comparisons. I have never known what my bodyfat% is. It does make me wonder though.
Your progress is amazing. Great work!2 -
I really appreciate all the feedback and encouragement! The women on this forum have been such an inspiration to me! Looking forward to getting started on a structured program focused on my shoulders, back, butt and arms!4
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I've read that DEXA is more accurate.
Proponents of both DXA and Hydro claim each claim to be the "gold standard" for BF measurement and to be more accurate than the other but independent sources report both to have a error factor of about 5%.
See:
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-6-dexa/
and
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-2/
That said, they are still the most accurate means of measuring BF that are commercially available.
While the results given may not be absolutely precise empirically, they are accurate w/in a known and reasonable degree of error and if you use the same method over time should give you a reasonably accurate graph of the trend.2 -
I've read that DEXA is more accurate.
Proponents of both DXA and Hydro claim each claim to be the "gold standard" for BF measurement and to be more accurate than the other but independent sources report both to have a error factor of about 5%.
See:
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-6-dexa/
and
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-2/
That said, they are still the most accurate means of measuring BF that are commercially available.
While the results given may not be absolutely precise empirically, they are accurate w/in a known and reasonable degree of error and if you use the same method over time should give you a reasonably accurate graph of the trend.
Thanks for the insight. If hydro results are generally lower, that works well for me
What about accuracy of online calculators and measurements?
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It's a great comparison. Regardless of the number, you've done fantastic! I've read that dexa is usually higher than the tank, so your results are consistent with that.1
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I've read that DEXA is more accurate.
Proponents of both DXA and Hydro claim each claim to be the "gold standard" for BF measurement and to be more accurate than the other but independent sources report both to have a error factor of about 5%.
See:
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-6-dexa/
and
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-2/
That said, they are still the most accurate means of measuring BF that are commercially available.
While the results given may not be absolutely precise empirically, they are accurate w/in a known and reasonable degree of error and if you use the same method over time should give you a reasonably accurate graph of the trend.
Thanks for the insight. If hydro results are generally lower, that works well for me
What about accuracy of online calculators and measurements?
Online calculators based on measurements have never been accurate for me - - always too high as compared w/DXA and Hydro.0 -
Damn. You look incredible. Front & back.2
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I know quite a few people hate them but I have a Skulpt (actually 2, one of each version) and while I have a bit of a love/hate relationship with it because some days it seems reluctant to give me a reading, or worse yet gives me numbers I really don't like! (Giant jumps in fat or decreases in MQ that can't possibly have happened overnight)
That said, most of the time it seems to be fairly accurate. I get a Dexa every 6 months and Skulpt claims +/- 2 from Dexa as their target... it's been + 1.x the last three scans.1 -
I've read that DEXA is more accurate.
Proponents of both DXA and Hydro claim each claim to be the "gold standard" for BF measurement and to be more accurate than the other but independent sources report both to have a error factor of about 5%.
See:
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-6-dexa/
and
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-2/
That said, they are still the most accurate means of measuring BF that are commercially available.
While the results given may not be absolutely precise empirically, they are accurate w/in a known and reasonable degree of error and if you use the same method over time should give you a reasonably accurate graph of the trend.
Thanks for the insight. If hydro results are generally lower, that works well for me
What about accuracy of online calculators and measurements?
Online calculators based on measurements have never been accurate for me - - always too high as compared w/DXA and Hydro.
Interesting. I always thought they showed lower results and were not accurate that way. I haven't had any dexas lately so I can't compare. Maybe it's an individual thing.
Thanks again for your response.
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Maybe it's an individual thing.I've read that DEXA is more accurate.
Proponents of both DXA and Hydro claim each claim to be the "gold standard" for BF measurement and to be more accurate than the other but independent sources report both to have a error factor of about 5%.
See:
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-6-dexa/
and
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-2/
That said, they are still the most accurate means of measuring BF that are commercially available.
While the results given may not be absolutely precise empirically, they are accurate w/in a known and reasonable degree of error and if you use the same method over time should give you a reasonably accurate graph of the trend.
Thanks for the insight. If hydro results are generally lower, that works well for me
What about accuracy of online calculators and measurements?
Online calculators based on measurements have never been accurate for me - - always too high as compared w/DXA and Hydro.
Almost certainly.
I am very muscular and stocky for my wt and height and I believe that BF calculators, based on body measurements, attribute more BF to me of this.
They normally give me results at the 18-20% level which as much as 50-100% more than as measured by DXA (13.4%) and Hydro (10.9%).1 -
I've read that DEXA is more accurate.
Proponents of both DXA and Hydro claim each claim to be the "gold standard" for BF measurement and to be more accurate than the other but independent sources report both to have a error factor of about 5%.
See:
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-6-dexa/
and
https://weightology.net/the-pitfalls-of-body-fat-measurement-part-2/
That said, they are still the most accurate means of measuring BF that are commercially available.
While the results given may not be absolutely precise empirically, they are accurate w/in a known and reasonable degree of error and if you use the same method over time should give you a reasonably accurate graph of the trend.
Thanks for the insight. If hydro results are generally lower, that works well for me
What about accuracy of online calculators and measurements?
Online calculators based on measurements have never been accurate for me - - always too high as compared w/DXA and Hydro.
Interesting. I always thought they showed lower results and were not accurate that way. I haven't had any dexas lately so I can't compare. Maybe it's an individual thing.
Thanks again for your response.
Very individual, and I'd suggest if some thought given to it - a known effect.
Using something like this that uses several measuring spots, and 2 different formulas.
www.gymgoal.com/dtool_fat.html
Of course the correlation between the measurements and BF% is still based on some averages, but you can see looking at that list if you have body parts that are outside the norm.
We've probably all seen people (or are one) that have bigger calves or forearms than rest of arm/leg would appear average to, or wrists that are very thin compared to bigger arms.
Or for women those variable hip to waist measurements.
Those type of non-averages will throw off the formula results by some amount.
But as it's been mentioned - measurements can be very consistent even if not dead on for accuracy (which is needed for ..... ).
The one thing I've seen complaints about on measurements is how to keep consistent ones.
Well, belly button is easy, and the smallest part of the waist is easy, and the widest part of the others is easy.
Where that widest spot is exactly will certainly move likely as fat is lost, but widest is widest no matter where it is.
So pretty easy.
The harder part is probably confirming the tape is going horizontal around a line (except neck has tilt to tape) for like waist or hips or abdomen.1 -
I have periodically gotten hydrostatic tests - my last one was @ 32% 5 weeks ago.
I decided to get a DEXA scan after 5 weeks of working hard, massively increasing protein and trying to really get my hormone issues under control by way of a sports nutritionist. I figured I would use that as my benchmark moving forward (and stop having to get wet). I was nervous b/c I heard that DEXA always tests a few percentage points higher.
I guess I'm "happy" to say that my DEXA also came out at 32%, because I think that means my hydro (if I was to do it again today) would have shown a lower number after the last 5 weeks.
It was also interesting to get bone density and visceral fat numbers. Maybe in a couple months I'll get one of each too, to compare - it is interesting stuff!0
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