Body fat percentage via DEXA scan

[Spartan_Dawg]

I had a DEXA scan yesterday.  I was floored by the results.

First, background: I used to be a competitive swimmer, have always been in good shape.  I'm 6'1'' and 175 pounds, and have been at that weight for about 3 years.  I do between 30 and 45 minutes of high intensity cardio 3-4 times a week, and lift weights 3 times a week.  I track everything I eat and drink, and with very few exceptions am always at a calorie deficit.  I can see clearly the top "four-pack" of my abs.  I have the v-cut.  I certainly have some fat around my lower abdomen, but most people would (and do) describe me as thin.  I do have very good muscle definition in my arms, legs, and chest.

So this DEXA scan, which is supposed to be the most accurate measure of body fat: it came back at 26 percent.  Twenty-six!!  In men my age, over 25% is often considered obese.  Even the guy running the lab (I had this done at a sports physiology department at a local university) said, "when you walked in, no way I would guess 26 percent.  I thought 18, maybe 20 at the outside."  I asked him if the machine was incorrectly calibrated, but he said no, it came back with a high confidence.

I'm not going to read too much into this - the eye test is probably more important anyway.  I'm going to continue to live a healthy lifestyle, and chalk it up to a bad scan, or maybe I was dehydrated or something.  But has anyone else out there seen such an anomalous result from a DEXA?  Have all my organs turned to fat?  Any ideas what's going on here?

[SunsetRunner]

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@Spartan_Dawg wrote:

I had a DEXA scan yesterday.  I was floored by the results.

First, background: I used to be a competitive swimmer, have always been in good shape.  I'm 6'1'' and 175 pounds, and have been at that weight for about 3 years.  I do between 30 and 45 minutes of high intensity cardio 3-4 times a week, and lift weights 3 times a week.  I track everything I eat and drink, and with very few exceptions am always at a calorie deficit.  I can see clearly the top "four-pack" of my abs.  I have the v-cut.  I certainly have some fat around my lower abdomen, but most people would (and do) describe me as thin.  I do have very good muscle definition in my arms, legs, and chest.

So this DEXA scan, which is supposed to be the most accurate measure of body fat: it came back at 26 percent.  Twenty-six!!  In men my age, over 25% is often considered obese.  Even the guy running the lab (I had this done at a sports physiology department at a local university) said, "when you walked in, no way I would guess 26 percent.  I thought 18, maybe 20 at the outside."  I asked him if the machine was incorrectly calibrated, but he said no, it came back with a high confidence.

I'm not going to read too much into this - the eye test is probably more important anyway.  I'm going to continue to live a healthy lifestyle, and chalk it up to a bad scan, or maybe I was dehydrated or something.  But has anyone else out there seen such an anomalous result from a DEXA?  Have all my organs turned to fat?  Any ideas what's going on here?

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So, swimmers tend to carry more body fat, because your body tends to add fat for buoyancy.

Runners tend to be lower in body fat, because the body tends to shed fat for better efficiency.

An "athletic weight" for males, can be calculated as (4 x height) - 128. So for your given height,

this would be 164 lb. (at between 5% to 10% bf). So you should test at about 12% to 18%.

[reuel]

perhaps you should have another scan?

i dont know about the 4 pack abs thing, because i know a guy who is probably overweight and still has a well defined 6 pack abs when he sucks his gut in. some people have good muscle definition even at a higher BF percentage.

[Heybales]

It's not supposed to be as vital for a DEXA scan as other methods - but did you present a properly hydrated body for the test?

Did they give you the protocol as far as eating and exercise and water prior to the test?

And most of the scans do multi-slice analysis, not truly the whole body.

So it is possible that if you hold the fat you got in the right place - you can fool the analysis and algorithms used to calculate BF%.

I'd suggest it should be consistent though. So 6 months down the road, another one should be accurate for amount lost, and more importantly, amount of LBM retained.

And while they say the machine is calibrated - is this a business that brings their machine in a truck to gyms for folks unannounced to have the test done?

Those have bad reputation of NOT being calibrated. Why spend money getting great calibration for accuracy, when you are measuring people that have not followed the protocol prior to test to be accurate that way?

Several here for several methods do an end of month gym run for cheaper than normal tests - then calibrate unit back in the office for more expensive tests.

[Spartan_Dawg]

So, they didn't give me any guidelines other than to not wear metal. They said to wear a tshirt and shorts, which I did. I may have been dehydrated - the test was at 9:30 am about 45 minutes from where I live and nobody told me to make sure I was properly hydrated.

It is a stationary unit at a university, so I doubt the calibration was set in a way to generate crappy results.

[Heybales]

That is good one then, they likely use it for research study participants, so needs to be calibrated all the time.

They are probably used to dealing with study folks that have not dieted, may do little to no exercise prior to starting the study and doing the test. So hydrate matters little for them.

But athletes could be a different story. Like if you had a huge swim workout night before and worked off a lot of carbs that your last meal never topped back off, you'd have changed the measurements.

That kind of thing.