Cut bulk with Dexa

Laces918
Laces918 Posts: 36 Member
edited November 27 in Goal: Gaining Weight and Body Building
I’m towards the end of a cut right now then moving in to a bulk. I will be getting Dexa scans along the way if anyone is interested if I get a few people as friends on here I will blog everything

Replies

  • sgt1372
    sgt1372 Posts: 3,997 Member
    edited June 2018
    FWiw, I have,had DXA scans and hydrostatic tests done every quarter for the past 2 yrs.

    People say that DXA is now the "gold standard" for measuring BF but I beg to differ. The results that get w/DXA are,always 3-5% higher than hydro and do not always correlate directly w/hydr (eg, DXA goes up when hydro goes down).

    For example, based on my results 2 weeks ago, my BF dropped from 8.3 to 7.7% per hydro but went up from 12.5 to 13.8 per DXA. I might not be at sub-8% but to look at me there's no way you'd guess that I'm over 13%.

    It was also confusing that DXA said that my VAT dropped to nil while also saying that my BF went up 1%. If I gained 1% BF, I don't how some of that wouldn't have also been reflected in VAT.

    So, at least in my case, I seriously question the accuracy and reliabilty of DXA and think that hydro is much better in this regard. In fact, based on this experiencei do not think I'll ever get a DXA scan again.
  • Laces918
    Laces918 Posts: 36 Member
    my issue with hydro is i feel like they are always low.. i have seen multiple 2 and 3 % readings that are obviously wrong. i have put a lot of time and effort in the past 5-7 years into different peoples body fat %'s. about 90% of people think they are lower than they really are.. lol my opinion when you think body fat % you mainly only think abs. someone could hold a lot of fat in their legs and not on their abs and you would never really know it but it obviously will result in a higher body fat % since it is on their body. I know a lot of people prefer the hydro I believe it is because it gives a more desirable #. my hydro showed 7.3 DEXA showed 11.1 obviously kindof like I said earlier i think im lower than 11.1., but know im not 7. It also showed I hold more fat in my legs than my core, which i can obviously pinch and figure out that is true. but at the end of the day nothing really seems like an exact science when you watch multiple body fat machines on multiple different bodies and see the wide range of readings.
  • sgt1372
    sgt1372 Posts: 3,997 Member
    edited June 2018
    Every method of BF measurement has its weaknesses but, based on my experience, hydro seems to have fewer than DXA.

    DXA was originally designed as a way of measuring bone density not BF and while DXA is very good at measuring the density of hard bone tissue w/xrays, I'm not so sure the xray densitometry it is as effective in measuring the density and weight of soft tissue (LBM & BF) based on the results that I have received over the past 2 yrs; at least 3 of which were seriously suspect.

    It's not that the DXA results are always higher than the hydro results that concerns me. It's that the DXA results are inconsistent and contradictory which calls into question their accuracy and reliability, which is not surprising since the BF estimate is not based on an actual physical measurement but based on a computer algorthim that makes a best guess of which of the soft tissue is BF vs LBM.

    Hydro is not so complicated. Fat floats and the weight of your BF is simply the difference between your weight both in and out of water. The main error factor is the air in your lungs, which also floats. If you have too much air in your lungs, your weight under water will be lower than it should be and your BF estimate will be in error on the high side.

    Of course, there will always be some air in your lungs when weighed under water but I am very good at expelling most of the air out of my lungs during a hydro test and now trust those results far more than I do the DXAs.
  • PaulChasinDreams
    PaulChasinDreams Posts: 439 Member
    Dexa results can vary greatly based on your body hydration level and/or if you have eaten recently and/or where you are with your food in your digestive system. I have a friend that wanted to do some tests with Dexa and see how much he could get different readings on them because like others point out the results had been varying so much and inconsistent. He has a discounted rate with a membership program. He got so many different fat and lean % numbers by changing his hydration, amount of food he ate the day before and day of the dexa etc and even had varied results in the same 24hr period with three different scans.
    For these reasons I am also looking towards the hydro testing to compare to.
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