DEXA scans and metabolic rate

One of the many opportunities afforded to me during this program is the ability to take part in a number of research programs.  All of them are opt-in, meaning that I got to pick and choose which to participate in and which to pass on.  A cool feature, not common in many research studies, is that they share the results of many of the tests with you.

After going over the list with the research coordinator, I decided to sign up for the dual-energy X-ray absorptiometry (DEXA) scan, the resting metabolic rate test, and the mixed-meal glucose tolerance test.  Each test will be repeated three times – once before I begin the program, once when I reintroduce food for phase 2, and once at the beginning of phase 3.

I later decided to withdraw from the mixed-meal test after receiving more information about the prep for it.  Since the tests are parts of different research studies, everything has to be as standardized as possible.  The diet options were not to my liking (there was literally one food I would eat on the list), and I had to follow it for three days.  That left the DEXA scan and the resting metabolic rate tests.

About two weeks ago I completed the first resting metabolic rate test.  The instructions for this were pretty simple.  I had a 12 hour fast beforehand, and couldn’t eat or drink anything with caffeine the day before.  The actual test was as easy as could be.  I literally had to lay there and do nothing.  For an hour.  While moving as little as possible.  No music, no books, no radio, just “resting”.  After the first half an hour they put a clear bubble over my head that measured the amount of calories I was exhaling.  It was very simple but SO. SO. BORING!!!!!  The end result was one number – 2140.  That’s the number of calories my body burns while at rest, to keep everything running exactly the way it is.  Exercise increases that number, and in order to lose weight I need to eat fewer calories than that each day.  As my weight goes down, that number will go down as well.

Last week I got the DEXA scan done.  This is a really cool kind of x-ray that measures bone density and body composition.  The arm (on the image above) moves slowly down the body, taking pictures of every part of you in about 10-20 minutes.  For now, the bone density results are more in addition to what else I can get from it.  However, the very kind nurse who was administering the x-ray told me they could use these scans as a baseline later in life when I’m being checked for osteoporosis. The body composition scan is more what the researchers are interested in for the Weight Management Program, and I have to say I was a little surprised with the results.

My overall body fat percentage is 54%, which is less than I was expecting to be perfectly honest.  The computer then further divided that into torso (53%), arms (49%), and legs (37%).  The 50th percentile of body composition for women is about 30% overall.  I definitely have some ways to go, but that’s nothing unexpected!  As with the resting metabolic rate, these percentages should go down as I lose weight.  I’m very excited to see how the next scan turns out!!


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