Scientist Reacts to Greg Doucette's Controversial Take on DEXA Scans | 57 - Longevity Reacts #4
Coach, bodybuilder, and powerlifter Greg Doucette published a video on his Youtube channel discussing what he sees as the shortcomings of DEXA scans and why DEXA scans are not, in fact, the gold standard of body composition measurement. He bases his views on personal experience as well as his interpretation of a 2019 study that examined how closely DEXA and MRI measurements correlate.
In this episode, Matt reacts to Greg's video and presents his own opinion about the validity of DEXA scan measurements. Together with Nick, he discusses what DEXA scans do and don't measure, potential sources of inaccuracy in DEXA scans, honest interpretations of scientific literature, and more.
A DEXA (dual-energy X-ray absorptiometry) scan is an advanced imaging procedure for measuring bone density and composition. DEXA scans utilize two different energy levels of low-dose X-ray beams—one absorbed mostly by soft tissue, and the other absorbed mainly by bone—to differentiate between bone, fat, and lean tissue. In so doing, they provide noninvasive and detailed information about bone health, risk of osteoporosis or fractures, and body composition. While medical practitioners typically perform DEXA scans on the lower spine and hips, they can also perform DEXA scans on the whole body for the purposes of early detection and intervention.
Check out the links below for further information and/or reading about some of the things we discussed in this podcast episode. Note that we do not necessarily endorse or agree with the content of these readings, but present them as supplementary material that may deepen your understanding of the topic after you listen to our podcast. This list is in no way exhaustive, but it’s a good start!
This is the paper upon which Greg bases his argument that DEXA scans are not necessarily useful tools for body composition measurement (though he does also state his opinion that studies are wrong half the time). This study examines the correlation between magnetic resonance imaging (MRI) and DEXA scans measurements of lean mass, and argues that while the cross-sectional correlation between the measurements is strong, the correlation of percent change over time is modest and thus DEXA scans may not be able to detect lean mass changes over time to a degree of accuracy necessary for use in clinical trials.
What Is a DEXA Scan and How Can It Help You?
This is an introduction to DEXA scans that covers the history of DEXA scans, how DEXA scans work, what happens during a DEXA scan, and how DEXA scans compare to imaging techniques such as CT scans, magnetic resonance imaging (MRI) scans, and x-rays.
Unexpected DEXA Scan Results? Here are Some Potential Causes:
You may have gotten your DEXA scan results back and balked at what you saw. This list addresses some possible reasons for DEXA scan surprises.
This study found a high correlation between visceral fat content measured by DEXA scans and the actual excised visceral fat content of mice, suggesting that DEXA scans are accurate tools for noninvasive fat distribution measurement.
This list of FAQs covers many questions people have about DEXA scans, including how much radiation exposure we receive from DEXA scans, height and weight limits, the safety of DEXA scans for pregnant wome, and more.
