Body composition testing

[Nemesis48]

I want to start getting body composition testing, there is a HUGE amount of misinformation, marketing bullshit and misdirection if you google.

I am curious if anyone has experience with multiple forms of testing, and to which they find is the most accurate.

My college nutrition/training class said that hydrostatic weighing was the gold standard - but how does it compare to bodpod/dexa?

Also if anyone knows where/if hydrostatic weighing is done in the central florida area, and/or costs - that would be appreciated. Looks like slim pickins.

 

[apizur**]

There's a gym in the hospital in Kissimmee, Celebration Health... it's like right by Olde Town.

Email Bill Kelley from there. I had an at-length conversation about this with him and he seems to know his shit.
http://www.celebrationfitness.com/personaltraining/yourtrainers

 

[Seriously-Dead]

Hydrostatic weighing is the gold standard, but it can be off by as much as 5-10% because it is just based off of formulas (things like bone density and glycogen content could affect it). DEXA comes in a close second to hydrostatic, but is susceptible to changes in hydration, so it's intra-individual variation is fairly off - you do get the added benefit of having a peak at your bone density, but there is considerable error even in that, as well as incomplete imaging (DEXA cannot capture a lot of parameters of bone strength that something like a pQCT would pick up). BodPod is okay, but it's intra-individual variation is terrible. It's okay for big groups of people where you take an average and know your SD, but for an individual the margin of error is way too large. Skinfolds are great for tracking change over time as long as the person taking the measurement is consistent in their technique, but the error rate of a one-off measurement is terrible. For someone like you who has loose skin from massive weight loss skinfolds will likely be very inaccurate, even in the hands of a seasoned measurer. BIA is just terrible, and definitely should be avoided at all cost.

The only true measure is post-mortem analysis. All others are just secondary measurements, so there will be error with any method on a living person. It's important to keep in mind that these techniques were developed for assessing body composition within groups, where a large enough sample size can overcome built in error. For a single person in a single measurement, there is considerable error with any method - but hydrostatic weighing's ballpark will get you the closest measure.

If you want to read more about it, Weightology did a good six-part write-up on this topic, and most of it agrees with what I've experienced in lab work:
http://weightology.net/weightologyweekly/?page_id=146

 

[Nemesis48]

Hydrostatic weighing is the gold standard, but it can be off by as much as 5-10% because it is just based off of formulas (things like bone density and glycogen content could affect it). DEXA comes in a close second to hydrostatic, but is susceptible to changes in hydration, so it's intra-individual variation is fairly off - you do get the added benefit of having a peak at your bone density, but there is considerable error even in that, as well as incomplete imaging (DEXA cannot capture a lot of parameters of bone strength that something like a pQCT would pick up). BodPod is okay, but it's intra-individual variation is terrible. It's okay for big groups of people where you take an average and know your SD, but for an individual the margin of error is way too large. Skinfolds are great for tracking change over time as long as the person taking the measurement is consistent in their technique, but the error rate of a one-off measurement is terrible. For someone like you who has loose skin from massive weight loss skinfolds will likely be very inaccurate, even in the hands of a seasoned measurer. BIA is just terrible, and definitely should be avoided at all cost.

The only true measure is post-mortem analysis. All others are just secondary measurements, so there will be error with any method on a living person. It's important to keep in mind that these techniques were developed for assessing body composition within groups, where a large enough sample size can overcome built in error. For a single person in a single measurement, there is considerable error with any method - but hydrostatic weighing's ballpark will get you the closest measure.

If you want to read more about it, Weightology did a good six-part write-up on this topic, and most of it agrees with what I've experienced in lab work:
http://weightology.net/weightologyweekly/?page_id=146

Thank you for the informative and exhaustive post.

Hydro it is - if I can find a place in Central Florida.

 

[Denoginizer]

Hydrostatic weighing is the gold standard, but it can be off by as much as 5-10% because it is just based off of formulas (things like bone density and glycogen content could affect it). DEXA comes in a close second to hydrostatic, but is susceptible to changes in hydration, so it's intra-individual variation is fairly off - you do get the added benefit of having a peak at your bone density, but there is considerable error even in that, as well as incomplete imaging (DEXA cannot capture a lot of parameters of bone strength that something like a pQCT would pick up). BodPod is okay, but it's intra-individual variation is terrible. It's okay for big groups of people where you take an average and know your SD, but for an individual the margin of error is way too large. Skinfolds are great for tracking change over time as long as the person taking the measurement is consistent in their technique, but the error rate of a one-off measurement is terrible. For someone like you who has loose skin from massive weight loss skinfolds will likely be very inaccurate, even in the hands of a seasoned measurer. BIA is just terrible, and definitely should be avoided at all cost.

The only true measure is post-mortem analysis. All others are just secondary measurements, so there will be error with any method on a living person. It's important to keep in mind that these techniques were developed for assessing body composition within groups, where a large enough sample size can overcome built in error. For a single person in a single measurement, there is considerable error with any method - but hydrostatic weighing's ballpark will get you the closest measure.

If you want to read more about it, Weightology did a good six-part write-up on this topic, and most of it agrees with what I've experienced in lab work:
http://weightology.net/weightologyweekly/?page_id=146

Awesome post, should be added to FAQs.

TS, why do you care enough to spend money on this? Is it in order to make weight for some competition or just to track progress? Why not just take pictures of yourself and compare over time?

 

[apizur**]

Irony is:

The only true measurement of health,

is death.