- Oct 30, 2017
I've never had one, never will. Seems like a bunch of cash to give me a number that doesn't really mean anything / that I can't really do anything with (and apparently a not massively reliable number either).A while back we talked about dexa scan accuracy. I wanted to post the study back then but did not have the time to find it. I think a lot of youtubers, even ones I follow and respect, put the dexa scan on a pedestal. From what I understand, it is more accurate on fatter individuals and less on lean. But then it is used to track changes and this study shows that is clearly not the case. Often described as the gold standard , that is patently false as the MRI has been shown to be 99% accurate when compared to post mortem. The MRI is not something accessible to most people though, so dexa scan has some place still and I think the value there is somewhat weak since it is still expensive (apparently not everywhere, do not bite my head off please) for what you get.
Full study here:
As you can see, the results are pretty bad for DEXA scans accuracy compared to MRI (again, shown 99% accurate compared to the only way we know how to actually measure which is in a cadaver). The top dot, for example, shows the DEXA result as 10% increase in muscle mass but in reality they were only 3% according to the MRI. The highest change in muscle mass shown at the farthest right dot was about 14% increase and yet the Dexa scan showed only like a% 6 or 7% increase. And there was an instance where Dexa showed a loss in muscle mass but MRI reveals they actually gained about 12-13% muscle mass. That is incredulous. This is not showing the within 1-2% error claim I have seen over reddit and youtube.
So I am curious how previous studies based on DXA may be re-examined or returned to.
I think it is relevant to note that DXA scans overestimated about as often as it underestimated, making it difficult to determine which occurs on an individual basis without the MRI to back it up.
Call me a hater of dexa scans, whatever. I do not hate dexa scans. I do think they are overhyped. And I think it is kinda important to know the limitations, like knowing the limitations of BMI is important when using BMI as a tool, same with CICO, calipers, impedance, etc..
Edit - Shame that was the last post on the page. I've edited a quote in.
Oh... I've just realised that I might need to have one for bone density, but that's obviously a different story (and I'm not paying for it!).