DEXA Scans - I did two - who else has experience?

gentle_sir_hulk
gentle_sir_hulk Posts: 52 Member
in Health and Weight Loss
DEXA scans are meant to be the gold standard for body composition.

I found it interesting to read the results, but having done 2 tests after 15kg weight loss in between showed some fairly random results (like one of my arms accumulating 3 kg of fat whilst I lost 15kg across the body?)

Does someone have a history of succcessfully measuring the body composition with DEXA scans? Did you see some data noise?

Thanks for any feedback

Replies

  • mph323
    mph323 Posts: 3,565 Member
    Were you doing any weight training during the 15kg weight loss? I do find it odd that you gained a significant amount of fat just in one arm. I had 2 scans a year apart, both at goal weight. In between tests I was doing recomp, though not as aggressive as I would have preferred, due to injury and age.

    My tests were pretty consistent. I didn't see anything I would question, and I did see a slight reduction in body fat, though it was a disappointingly small decrease. On the other hand I was 67 and 68 when I did the tests so I was happy to see that I at least was maintaining my lean body mass.

    You might have a discussion with someone at the facility where you did the testing to see if they have any insights into the anomaly.
  • PAV8888
    PAV8888 Posts: 14,246 Member
    There is auto/manual selection of your shape. What gets selected influences the results. You could MAYBE ask for someone (same person) to go through both tests and review/redo them. Or at least review the recent
  • frankwbrown
    frankwbrown Posts: 13,032 Member
    edited September 2021
    Movement seems like the most plausible explanation, doesn't it?

    I've had three DEXA scans roughly three months apart, and am scheduled for a fourth the end of this month.
    Here are the overall results:
    1. 09/30/20: wt: 305.0, fat mass: 135.6, lean mass: 169.4, BFP: 44.5%
    2. 12/20/20: wt: 277.3, fat mass: 119.5, lean mass: 157.8, BFP: 43.1%
    3. 03/19/21: wt: 264.3, fat mass: 104.3, lean mass: 149.8, BFP: 39.5%
    My major concern is the amount of loss of lean mass. I am working now to reverse that trend, and I'm hoping this next scan shows some improvement.

    As far as the details of left vs right, upper/lower, etc., I don't see anything unusual. Although there was one thing: my first scan was done in a mobile unit and it wouldn't quite cover my body width, so it had to interpolate a bit. To avoid that problem, my subsequent scans were done at a brick and mortar facility.
  • corinasue1143
    corinasue1143 Posts: 7,464 Member
    edited September 2021
    Jthanmyfitnesspal wrote: »
    I agree that it sounds totally ridiculous that you would lose 15kg, yet gain 3kg of fat just in one arm. Was this a medical DEXA scan or one done by a sports clinic? I have no evidence, but I could imagine that the ones done for non-medical reasons might not have the fidelity of medical ones.

    I actually have a technical background related to DEXA, which gives me just enough knowledge to be dangerous: is it possible that you moved a little bit during the scan?

    I’ve only had one dexa, and I know 0 about them. Never heard of it until I had it. My legs were all messed up on the test. They looked like washboards. The test-taker said it was because I was so unsteady. My balance and muscles on one side were so bad I usually leaned on something when I stood still. They wouldn’t let me during the test, so I just stood there and shook.
  • sgt1372
    sgt1372 Posts: 3,997 Member
    i have quarterly DEXA and hydro results for over 5 yrs from 2015-2020 b4 the C19 pandemic shut everything down & b4 I stopped lifting seriously.

    Overall, the results were very consistent and were generally as expected. Of course, there were some variations that lacked explanation (like when I got a ZERO VAT reading, which was highly unlikely) but overall I found my DEXA results to ne extremely reliable.
  • springlering62
    springlering62 Posts: 8,452 Member
    edited September 2021
    I had a couple of Dexas. When reviewing the results, the operator explained that it’s very common for bodies to not be perfectly symmetrical, and that I had about a pound of so difference between sides.

    She explained it as being like the ladies who have one breast bigger than the other, that it’s perfectly normal, and quite common.

    One of my feet is also almost a size larger than the other. 🤷🏻‍♀️
  • gentle_sir_hulk
    gentle_sir_hulk Posts: 52 Member
    Thank you all for your comments

    I have been weight training regularly in parallel to my diet/lifestyle change and I would have liked to see muscle mass increase. it seems there is variability in results for many reason, and looking at the pictures of the scan I noticed that part of my arm was not visible, and that the scan estimated my weight 20lb lower ,.. so perhaps my positioning on the machine had a lot to do with it.

    Really appreciate the comments - thank you! I will come back with an update on my next test!

    Oh one more question - any of you did a test to also check for visceral fat? I dont get a DEXA scan for that in New York, I have to go somewhere far in New Jersey and have not yet ventured that far ...
  • Jthanmyfitnesspal
    Jthanmyfitnesspal Posts: 3,522 Member
    corinasue1143 wrote: »
    I’ve only had one dexa, and I know 0 about them. Never heard of it until I had it. My legs were all messed up on the test. They looked like washboards. The test-taker said it was because I was so unsteady. My balance and muscles on one side were so bad I usually leaned on something when I stood still. They wouldn’t let me during the test, so I just stood there and shook.

    I thought all the DEXA machines worked lying down!
  • Cheesy567
    Cheesy567 Posts: 1,186 Member
    Did both DEXA scans include all of both of your arms? There are size limits to the machines, and if a person doesn’t fit within the scan area they’ll leave a part of an arm out. Perhaps part of your arm was out of the scan the first time, but all of you fit in the scan the second time? That’d account for the increase in the BF% in that arm only?
  • nooshi713
    nooshi713 Posts: 4,877 Member
    When I was my healthiest, working out and lifting weights regularly, toned, size 4…..a Dexa scan said I was obese. They are supposedly reliable but I don’t think so.
  • sgt1372
    sgt1372 Posts: 3,997 Member
    rabatin1 wrote: »
    Oh one more question - any of you did a test to also check for visceral fat? I dont get a DEXA scan for that in New York, I have to go somewhere far in New Jersey and have not yet ventured that far ...

    All of my DEXA scans included a VAT measurement. There was no separate test required

  • heybales
    heybales Posts: 18,842 Member
    frankwbrown wrote: »
    Movement seems like the most plausible explanation, doesn't it?

    I've had three DEXA scans roughly three months apart, and am scheduled for a fourth the end of this month.
    Here are the overall results:
    1. 09/30/20: wt: 305.0, fat mass: 135.6, lean mass: 169.4, BFP: 44.5%
    2. 12/20/20: wt: 277.3, fat mass: 119.5, lean mass: 157.8, BFP: 43.1%
    3. 03/19/21: wt: 264.3, fat mass: 104.3, lean mass: 149.8, BFP: 39.5%
    My major concern is the amount of loss of lean mass. I am working now to reverse that trend, and I'm hoping this next scan shows some improvement.

    As far as the details of left vs right, upper/lower, etc., I don't see anything unusual. Although there was one thing: my first scan was done in a mobile unit and it wouldn't quite cover my body width, so it had to interpolate a bit. To avoid that problem, my subsequent scans were done at a brick and mortar facility.

    I think you know from other threads - since LBM (Lean Body Mass) means everything NOT FM (Fat Mass), water counts as LBM.
    Less blood volume to support less body, less interstitial water volume for less body.
    In a diet less carbs stored in muscle so less attached water weight.

    Now, that ain't accounting for that 50% drop in LBM reading - that's still massive, considering it's usually thrown out that unaware dieters will usually lose upwards of 30% LBM.

    I think this is good example of knowing the tests and potential for errors, and how that can throw out some troublesome looking figures.
    May be true, may not be.

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