Dexa Scan Body Composition Test Results

Today, I visited Dexafit and had 3 things done.  First, I had a dexa scan (DXA scan) done to determine my body composition, including body fat percentage.  Then, I had my resting metabolism tested.  Finally, I had a Fit3D scan which made lots of measurements of my body.  The whole thing was incredibly interesting and informative and I think getting updated results over time will be very motivating.  Since this is all long I will do a separate post for each procedure.

Here is the post for my resting metabolic rate testing.

And, here is the post for my Fit3D scan.

The Dexa Scan

I will start with the dexa scan.  I described the dexa scan in my prior post talking about the upcoming testing.  The scan was pretty much what I expected from the scans I had previously had for bone density purposes.  You lay on a table very still.  I took off and my shoes and my ankles were actually strapped together and I was told to put my hands underneath my posterior.

Then, the scanner slowly moved down my body from head all the way:

Body Composition Results

I have to say I was totally surprised by my body fat percentage result.  I had totally steeled myself for getting a higher percentage than I did on my Bod Pod testing (twice) in 2015. Dexafit itself gives some reasons why its body fat percentages can be different those from a Bod Pod or other methods of testing.  I did a lot of research before have a dexa scan and found numerous people and articles talking about testing at least 5 percentage points higher for fat with the dexa scan than with other methods.  And, yet…as it turns out, I did not.

In September, 2015 my Bod Pod testing found that I had 45.3% body fat.  My test in December, 2015, found that my body fat percentage was 46.6%.  The tester (same person each time) said that the second result was within the margin of error and so it didn’t necessarily mean that there had been an actual change. During that time, I had lost a little weight but had been strength training consistently with a trainer.

As I discussed in my last post, given all of the factors of different testing methods and my surgery and weight gain and loss since then, I expected to be at least 5 percentage points higher.  I felt that most of that would be due to difference in testing methods with my actual fat percentage truly being about 1% or so higher.  But, no.

On the dexa scan, I tested at 45.4% which was virtually the same as my September, 2015 Bod Pod testing.  I must admit that I was very surprised by this. Interestingly, this was not the thing that most surprised me.  I will discuss that in my next post.

So, if Dexa scans usually result in a much higher body fat percentage than Bod Pod tests, why is this one virtually the same as my Bod Pod result?  I think that there are 3 possible answers.  And, I suspect the truth is some combination of the three:

Possibility 1 – My body composition was improved in the last 2 years.  In this scenario, I have more muscle now and less fat than I had then, so the dexa scan represents a true improvement in body composition.  In other words, had I had the dexa scan 2 years ago, I might have tested about 50% body fat on it, but I’ve improved since then.  And, if I did a Bod Pod right now I would probably test closer to 40% than 45%.

This explanation would be really good and I would love it.  But, I’m not really buying it.  At my first Bod Pod test, I weighed 147.8 pounds.  Fat mass was 66.96 pounds and fat free mass was 80.846 pounds.  Fat free mass was everything other than fat: Muscle, bone, organs, and water.  On my dexa scan, it says my fat mass is 68.1 pounds, lean tissue is 78 pounds and bone mineral content was 4 pounds.  Now, to be comparable to the Bod Pod, you have to add the bones to the lean tissue to get 82 pounds for fat free mass.  Well, that is a little over a pound more than with the Bod Pod.  So, I guess I could have built a pound of muscle.

But, wait!  My fat mass is also over a pound more than in 2015.  Oh, one other thing.  Dexafit had my weight on this at 150.1 pounds.  My weight this morning at home with no clothes was very similar to when I did the Bod Pod.  But for the dexa scan I was wearing regular clothes and I had a bottle of water on the way to the test.  Those things added a couple of pounds.

Another reason I don’t think I have had a true large change in body composition is that my BIA home scale doesn’t reflect that my body fat has decreased.  In fact, it has gone up about 1% in the last year or so as I stopped doing strength training due to my surgery.

It is possible that given my surgery that my body fat improved by a percent or so.  But, honestly, I don’t think I have had any major change in body composition.

Possibility 2 – The Bod Pod gives most people a body fat percentage lower than dexa scan does.  It would have done that for me as well, but its bone density assumptions were inaccurate for me.  The Bod Pod uses a two compartment model where it determines fat free mass and fat mass.  It does not directly measure your bone density.  Instead, it uses standard formulas to estimate bone density.  This can result in inaccuracies and is discussed in the Dexafit article I linked to above.  Bodybuilders, for example, often have more dense bones than the average person.  For that reason, other methods of testing often underestimate their body fat percentage.  On the other hand, for older people, particularly those with osteoporosis, the standard formulas over overestimates their bone density.  The result is that those methods can find that they have higher body fat than they really do.

A dexa scan doesn’t rely on formulas to determine bone density.  Instead, it directly measures bone mineral content.  This can result in some people (like bodybuilders) having a result for higher body fat percentage on a dexa scan than would be shown on other tests.  But, for someone like me (older with osteopenia that is close to osteoporosis), this can result in a dexa scan showing a lower result than on other tests.

I suspect that is part of what happened here.  A dexa scan measures all of the body including internally while other tests do not.  Looking at that alone, I probably would have had a higher result on the dexa scan than on the Bod Pod, just like most other people.  But, I have a lower bone density given my age.  Perhaps that lower bone density was enough to outweigh the higher percentage I would have gotten compared to the Bod Pod.  In other words, the Bod Pod back in 2015 would have given me, say, a 40% body fat percentage if I had actually had the bone density it assumed, but I actually had less bone density so it estimated my body fat percentage as 45% instead.  The dexa scan got my bone density right so it measures me close to what the Bod Pod said.  It didn’t do that because the two tests are consistent. Rather, the Bod Pod was inaccurate for me in 2 ways.  First, the way that normally causes a Bod Pod to measure body fat lower than a dexa scan and, second, by overestimating my actual bone density.

3-The dexa scan is simply inaccurate for me today.  If I went back and tested tomorrow, maybe I would test at or near 50% body fat.  This has some appeal to it as an argument as well.  The dexa scan is considered the gold standard for measuring body composition as applied to groups of people.  For the individual, however, it does have a margin of error and isn’t exact.  So, maybe it simply underestimated my body fat percentage.

So what do I think?  My guess is that there is some truth to all of these explanations.  While I haven’t done strength training in awhile I did continue to do it after having my Bod Pod test.  Maybe I did build at least some muscle that has been retained.  Maybe my surgery did slightly improve my body composition as well.  I suspect that the bone density assumptions are a big part of why my Bod Pod result wasn’t around 40% in 2015.   For me, I definitely fit in the population where getting actual measurements of my bone mineral content will probably lead to a more accurate result.  And, there may be some variability in the dexa scan.  I think the important thing there is to test over time and see what kind of change occurs over time and to wait until I think there has been a big enough change to be outside the margin of error.

Visceral Fat and Android/Gynoid Ratio

One of the other things you can get from a dexa scan is information about your visceral fat mass and your android/gynoid ratio. This was something I was really interested in.  The Android region of your body is the part around the abdomen.  Someone with fat in that area is often called apple shaped.  The Gynoid region is the part around the hips and thigh.  The person with fat there is often called pear shaped.

I have always known I was at least mildly apple shaped.  Even when I weighed 119 pounds, my waist was almost 28 inches.  I never had a narrow waist and never had a flat tummy even when quite low in weight.  After having a child and gaining a lot of weight, I was much more apple shaped:

I super hate how I looked in that picture but it shows how I looked at near my high weight and post-pregnancy.  A decided apple.

I was always concerned about this because it is the apple shape that is associated with certain negative health problems.  Part of that is because apple shaped people sometimes can have a lot of visceral fat.  Visceral fat is the fat around your organs inside the body.  Visceral fat is associated with metabolic disorders and is far more dangerous than subcutaneous fat.  When I had my tummy tuck and upper abdominal liposuction, most of my abdominal fat was removed.  But, this wouldn’t do anything about visceral fat.  I did ask my surgeon if he thought I had a lot of visceral fat.  He did not.  He said he thought I was average to a bit below average.  I liked hearing that, but really wanted find this out on the dexa scan.

The dexa scan gave me 2 pieces of information that I found helpful.  First, it said that my visceral fat was 2 pounds.  While I would like this to be lower, I have done enough reading to know that this isn’t bad.  Also, my android fat mass was 5.1 pounds.  The tester said it was good that I had so little visceral fat compared to my android fat mass.  For what its worth, I think most of that is in my back.  Most of the subcutaneous fat on my abdomen is gone, but I do have it on my back.

I also found this study which was comparing the accuracy of using DXA to MRI for measuring visceral fat.  One of the charts gives the mean visceral fat mass for the participants.  For white women as a group, the mean by dexa scan was 1.77 kilograms.  2 pounds of visceral fat is about .9 kilograms.  So, I was well below that.  For white women with a waist under 88 cm, the mean was 1.02 kg and for high waist above 88 cm, it was 2.42 kg.  I mention both waist measurements because I am under 88 cm under some waist measurement locations and am just above it on others.  In any event .9 kg is fairly average for the low waist group and is low for the high waist group.  Basically, it seems like my surgeon was right.  I am average or slightly below.  I was super happy about this.

The other thing they gave me was an Android/Gynoid ratio.  My Android body fat percentage was 47.1% and my Gynoid percentage was 46.7%.  That made my ratio 1.0 which is good.  Basically, after surgery, I am a slight apple but not all that much.  I do want to lose the visceral fat that I do have (losing fat through diet and exercise is basically the way to do that), but things are not too bad.

Here is an image where you can see the fat distribution in my body:

This was really interesting to me. The yellow is the high fat area.  For example, you can definitely see that the saddlebags on my thigh are some of my higher fat areas.  If you look at my torso, there is not a huge amount of yellow on the front.  I think that is because most of my subcutaneous fat in that area is on my back and doesn’t really show in this image.  Still, looking at the above, I can definitely see that I still have fat to lose.

Am I Balanced?

One thing that the scan also does is give my body fat percentages for the different parts of my body as shown in the Body Composition analysis above.  The scan also gives you the result for each side.  So my body fat percentage is less in my right arm than the left.  This is because my lean mass is a bit higher in the right arm which is typical since I am right handed.  For my legs, there is very little difference between the two sides.  Basically, they look to see if there is any imbalance between the two.  If one side had a lot more lean mass than the other then that might be a problem and might increase chance of injury.  In my case, though, I didn’t have any real imbalance.

What Now?

Overall, I was pretty happy with the results.  I mean I know that my body fat percentage is terrible.  But, I think this is more accurate overall than what I had before and I was very happy with the visceral fat result.  The recommendation was to retest in about 3 months.  I will see where I am then and will test if I’ve seen some changes in my body that warrant retesting.  That is, if I have lost some weight and have continued with strength training then it would make sense to retest.  If I haven’t lost any weight and don’t strength train then it wouldn’t be worthwhile.  And, I want to have a big enough change in results that I can feel any new numbers represent true change and not just a difference within the margin of error.

I paid $313 to be able to take 4 of the main Dexafit tests (Dexa scan, RMR test, and VO2 max) over the course of a year, plus a monthly Fit3D scan.  I can also take extra tests for $75 each.  I expect I will use my 2 remaining tests on dexa scans.

Once I get finished posting my results on the other two tests I will do a post about what I plan to do over the next few months.

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