DEXA scan for body fat % and lean muscle mass

Earlier this week I went for a DEXA scan to measure my body fat %. More for interest than anything else. I had researched different body fat measurement systems hydrostatic measurement, calipers and BioElectrical Impedence and the DEXA (Dual Xray) method is considered “the gold standard” with the least amount of error.

This scan is able to use X-ray at two different energy levels to divide the body into three components bone, lean mass and fat.  There is a very complete explanation of how it does that here.

I found several facilities locally that have a DEXA machine, and choose the Office of Nutrition Services at Eastern Michigan University. It was super easy to schedule via email and I believe they even have a facebook page where they will answer specific questions.

So we arrived for our appointments and everything was very straightforward. They had advised not to wear any metal even jewelry, zippers and underwired bras and I had read not to eat within two hours of the scan although they didn’t advise this. Obviously you shouldn’t have the scan if you are pregnant since it uses x-ray and they say you shouldn’t have had any x-rays etc. within the previous five days.

DEXA machine

DEXA scan machine

The actual scan was very quick, you lie on a table and the scanning head passes over you, it is a very open set up. The results are ready right away and the dietician did a great job of taking me through everything.

DEXA scan image

Scan image

So the scan showed that of my total 129.1 lbs, 96lbs are lean muscle, 5.65lbs are bone (doesn’t seem much does it?!) and the remaining 27.31 lbs are fat. That corresponds to a 22.1% body fat, apparently putting me at the 16th centile for my age. The report breaks down the composition for each body region, each leg and arm, trunk and hips.

They also give you  an assessment of bone density – the original purpose of this machine – and I had a T score of 0.8 and Age Matched Z score of 1.1. The T score compares you to a Young-Adult and anything above -1 is considered good. I passed with flying colors!

So, what does it all mean???

There is varying information and recommendations on body fat levels. The Fitness Institute of Texas (part of University of Texas at Austin) recommends a body fat % between 21 and 32% for women, considering anything below 21% Very lean/Underweight. The Built Lean website offers various different studies and charts.

Body fat percentages women Jackson Pollock

Body fat percentages for women based on Jackson Pollock study

So based on this I fall at the leaner end of “ideal”.

I thought these images were quite interesting from the same site. It obviously depends upon your fat distribution, but I would say that the 20-225 image is a pretty good match to me, maybe a good day to day visual measure or if you don’t have access to a DEXA machine.

Visual guide body fat

A visual guide to body fat percentage

Have you ever had a DEXA scan or had your body fat % measured another way? Would you be interested to know?




7 thoughts on “DEXA scan for body fat % and lean muscle mass

  1. Very cool!! I’m going in this afternoon for my very first DEXA…
    I kinda wish I had done one a year or two ago, when I first started losing weight – but, considering I’m now working on toning/leaning/building muscle, I figure this is as good a place as any to “baseline”. 🙂

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