Hydrostatic Body Fat Testing

veganbettie

I recently had my body fat tested via water displacement or the hydrostatic body fat testing and I'm just curious if anyone has done that and had the results be inaccurate. I realize they dunk you 3 times and then average it out but I'm just super surprised by my results.

back in 2017 I was at 29% and I just recently tested, granted after losing about 45 pounds and now I'm down to 16%. I really don't lift weights, I just run and count calories, I hardly even really focus on my protein or macros. I'm a 34 year old female.

I'm just concerned that the results are inaccurate, I really don't have a ton of fat on my body, I do look thin, but i'm just baffled. I'm not really sure if I should just retest in a few months, or if I should trust it or if it even really matters....

Anyway, anyone else get dunked and not have accurate results? Or do I just chill out and accept that my body is responding well?

heybales

I'll just comment that as a woman, your body would be fighting a BF% that low if true, and you would normally have some side effects that would be apparent.

You have visible abs?

https://images.app.goo.gl/fYfctgkxNYxarzVf9

veganbettie

Right? I still have my period, not losing hair, but I am cold constantly. Anything below 75 degrees I need a sweater. It's been a while since I've done blood work though so that could be iron.

I do not have visible abs (when flexing I'm starting to see definition), I look more like the 20% range. My upper body is very lean, I generally hold my weight in my lower half.

I know there is margin of error with any body fat testing, but really that much?!

sijomial

I've always had my doubts about hydrostatic testing as my one super power in a swimming pool is to sit perfectly comfortably on the bottom of the pool - even when quite chubby.

Maybe I have unusually dense bones? Dunno!!

16% for a female is pretty lean, I think you would know.

veganbettie

I love how I trusted it when it said I was 29% but I can't trust it at 16%.

Google says the margin of error is between 1.8 to 2.8 %, so i'm guessing i'm closer to 20%. I'll get re-dunked in a few months and see what it says.

I really expected it to be more like 22%, I feel like skin and bones, but skinny fat, but who knows, maybe i have more muscle hiding than I thought, my legs and arms are decently defined.

Thanks guys.

Theo166

I read it's accurate when done properly, but I suspect there is a huge risk of error depending on how much air you have left in your lungs. As @sijomial noted, it makes the difference between floating on top of the water or sinking to the bottom of the pool.

ninerbuff

16% is lean for a female. Any pics?

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veganbettie

hopefully that works.

If the error can be up to 3% I would assume I'm at least in the 20% range. How annoying.

sijomial

Personally I find the text commentary on Builtlean more useful than the female pictures as there's a lot of variance in how people carry their muscle and fat.....

"Body Fat Percentage Women 15-17%
This is still considered a very low body fat for women, which is similar to the 6-7% body fat for range men. Many bikini and fitness models will reach this body fat level and some may not be able to menstruate. Muscle definition in the abs, legs, arms, and shoulders is apparent, there is some vascularity and some separation between muscles. Hips, buttocks, and thighs generally have a little less shape because of the low body fat."

I'm also not terribly convinced if someone is aspiring to a certain look and getting reasonably lean that body fat testing with uncertain accuracy is any more helpful than the mirror (backed up with progress photos). You look to be at that point where small reductions in fat and/or increases in muscle bring very clear changes. e.g. muscle definition starts to show more clearly.

veganbettie

sijomial wrote: »

Personally I find the text commentary on Builtlean more useful than the female pictures as there's a lot of variance in how people carry their muscle and fat.....

"Body Fat Percentage Women 15-17%
This is still considered a very low body fat for women, which is similar to the 6-7% body fat for range men. Many bikini and fitness models will reach this body fat level and some may not be able to menstruate. Muscle definition in the abs, legs, arms, and shoulders is apparent, there is some vascularity and some separation between muscles. Hips, buttocks, and thighs generally have a little less shape because of the low body fat."

I'm also not terribly convinced if someone is aspiring to a certain look and getting reasonably lean that body fat testing with uncertain accuracy is any more helpful than the mirror (backed up with progress photos). You look to be at that point where small reductions in fat and/or increases in muscle bring very clear changes. e.g. muscle definition starts to show more clearly.

Thank you! Really I was just curious and I'm almost at the point where I'm going to stop eating at a deficit and start really try to put on muscle. I just started to go down a rabbit hole of wait that doesn't seem accurate. Regardless I'm happy where I'm at at the moment and ready to keep pushing forward. I also was curious as I have only been doing cardio to see where I was at. Just want to be healthy and fit at this point.

Thanks!

sgt1372

I've had many hydro and DEXA tests done at the same time over a 5 yr period, as often as quarterly, in the past.

I did both hydro and DEXA initially because I wanted to compare the results for comparative validity.

What I found was that the hydro and DEXA results varied similarly (up/down) but that the hydro results were always lower than DEXA by about 2-3%.

The main error factor in hydro is how much air you can expell air from your lungs. Air causes you to float (as does fat). So, if you do not expell as much air from you lungs as possible, your BF% will be higher.

The operator of my hydro tank said that some ppl obviously can do this better than others. In my experience, you have overcome a feeling of "drowning" or "suffocation" to get as much air out of your lungs, which is easier said than done

You can try to train yourself to do it by spending some time w/your face under water in a pool or bathtub while trying to blow the air out of your lungs.

But, f you can't expell enuf air from your lungs no matter how hard you try, I suggest just getting a DEXA test instead which is far easier to get do (all you do is lay under the moving arm of the scanner).

DEXA also provides much more data than hydro, like bone density, bone vs muscle mass wt, BF distribution by body areas and VAT. Hydro will just give you a total BF%.

Frankly, the only reason I kept doing hydro, even though it provided less data than DEXA, was because It gave me consistently lower results than DEXA.

LOL!

veganbettie

sgt1372 wrote: »

I've had many hydro and DEXA tests done at the same time over a 5 yr period, as often as quarterly, in the past.

I did both hydro and DEXA initially because I wanted to compare the results for comparative validity.

What I found was that the hydro and DEXA results varied similarly (up/down) but that the hydro results were always lower than DEXA by about 2-3%.

The main error factor in hydro is how much air you can expell air from your lungs. Air causes you to float (as does fat). So, if you do not expell as much air from you lungs as possible, your BF% will be higher.

The operator of my hydro tank said that some ppl obviously can do this better than others. In my experience, you have overcome a feeling of "drowning" or "suffocation" to get as much air out of your lungs, which is easier said than done

You can try to train yourself to do it by spending some time w/your face under water in a pool or bathtub while trying to blow the air out of your lungs.

But, f you can't expell enuf air from your lungs no matter how hard you try, I suggest just getting a DEXA test instead which is far easier to get do (all you do is lay under the moving arm of the scanner).

DEXA also provides much more data than hydro, like bone density, bone vs muscle mass wt, BF distribution by body areas and VAT. Hydro will just give you a total BF%.

Frankly, the only reason I kept doing hydro, even though it provided less data than DEXA, was because It gave me consistently lower results than DEXA.

LOL!

Hahaha that's excellent. I mean I'll take 16% lol. I've always been somewhat dense (queue jokes), but that's freaking low. I don't believe I have a dexa scan near me, I was looking, but really this is all curiosity sake obviously, so I suppose it doesn't matter. My body fat clearly went down so I'm happy with that.

Being dunked is a trip, it really does feel like you're drowning and the operator made it really clear that any air in my lungs would count against me, so I got out as much as I could, which clearly, I did well. Lol

FitnessCurmudgeon

.

ninerbuff

veganbettie wrote: »

hopefully that works.

If the error can be up to 3% I would assume I'm at least in the 20% range. How annoying.

I would say by looking at the pic, you're about 20%. Still great. Many women would kill for your bod.


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veganbettie

ninerbuff wrote: »

veganbettie wrote: »

hopefully that works.

If the error can be up to 3% I would assume I'm at least in the 20% range. How annoying.

I would say by looking at the pic, you're about 20%. Still great. Many women would kill for your bod.


A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 30 years and have studied kinesiology and nutrition

Thank you! I'm pretty happy especially where I've come from. 😌