Margin of error for DEXA is about 5%.
Congratulations , this is nearly perfect body recomp. I’ve started using tape measurements on various parts of my body to judge body recomp results. I can lift longer and heavier, but since I’m at a maintenance or deficit when it comes to calories, there hasn’t been any muscle growth.
1 Like
Rapan
#62
DEXA: The Verdict
Despite the fact that DEXA represents a 3-compartment model, its error rates are no better than hydrostatic weighing, and in some cases is worse. Like other techniques, DEXA does well when looking at group averages, but not so well when looking at individuals. Individual error rates tend to hover around 5%, although some studies have shown error rates as high as 10%. When looking at change over time in individuals, error rates have hovered around 5% in some research, although other research has indicated DEXA to perform much more poorly. For these reasons, I do not recommend DEXA for tracking change over time in individuals. If you do use DEXA for tracking change over time, I recommend very long time periods between measurements (a minimum of 3-6 months), as you will need a minimum of a 5% change in body fat to reliably detect a true change in body fat in most people.
2 Likes
Welcome to my club. Despite the fact that my muscles are as strong as ever, measured by the weights and reps I can do, they aren’t as large as they were five years ago.
Of course, at my age, I am just happy to keep the strengh.
3 Likes
Bingo. I’m not happy to join the club but here I am.
I’m confused about the accuracy of DEXA vs US Navy Body Fat Index, so I asked Gemini…
He/She Said:
If you’re fit, have an evenly muscular build, and your simple US Navy Body Fat Index measurement comes in around $17%, you’re probably asking: Why bother with the cost and radiation?
You’re absolutely right to be skeptical!
The Paradox of Precision
For someone in your position, who is already well within the healthy range and has a low waist circumference, the $17% estimate from the tape test is likely functionally accurate.
While DEXA is technically the “gold standard,” scientific articles confirm its high individual error rate (sometimes 5% or more) makes it unreliable for tracking small changes. If you only want to know if you’re staying on the “right health track”, that 5% error margin means:
- Your DEXA reading could easily be 14% or 20%.
- You need a huge change (at least 5% body fat change) before the DEXA can definitively confirm you made a true physiological change.
The Real Reason for the Scan
If your only goal is to track your overall body fat percentage for health reasons, the DEXA offers minimal advantage over the highly consistent and free tape test.
The only genuinely unique and valuable data DEXA provides (which justifies the tiny dose of radiation) is:
-
Bone Mineral Density (BMD): Critical data for healthy aging, especially once you hit your 60s, which no other body composition test gives you.
-
Visceral Fat Quantified: The exact amount of deep organ fat (though your low waist circumference of 82cm already suggests this risk is minimal).
Conclusion: If you’re staying fit and healthy, skip the cost and radiation unless you need specific bone or asymmetry data. Trust the combination of your tape measure and your good lab results!
1 Like
Mri is the gold standard, not dexa
2 Likes
Raquel
#67
Hello Joseph, great results! 15.3% body fat, denser bones, dramatically higher strength, and endurance coming back to peak levels.
The muscle mass “plateau” you’re seeing on DEXA is temporary and completely expected once you re-introduced serious cycling endurance work (directly suppressing mTOR, which rapa and/or FMD should already do too.)
Quantity phase, now to quality phase, specifically for hypertrophy for a short, intense block. Not sure how you stand about carbs, but maybe more carbs around leg days could unlock the leg growth again?
2 Likes
@Raquel Thanks. For now I’m contemplating my goals. Why do I want more muscle mass? I don’t have a reason. I think I should have a reason for my goals. Adding back the cycling has brightened my world. I’m much happier when I’m riding. Perhaps my goal should be to retain my muscle mass despite a lot of cycling? I like puzzles.
2 Likes
medaura
#69
I thought the DEXA’s margin of error was closer to 20%
