Editing User:Madprime/How do gendered algorithms relate to my "real" body composition?

My Withings scale estimates my body composition (percent fat, muscle, etc.) -- but I wonder whether the accuracy of this has drifted in past years. I identify as non-binary (trans FtX) and since fall 2020 I've been taking weekly testosterone. After a couple years targeting cis-male levels, the physiological effects include things like fat redistribution and increased muscle growth.

I'm far from fit: I've put on weight during the pandemic (BMI over 27), and don't routinely exercise. Regardless of which version -- male or female -- is "more correct", I know my "fat composition" is higher than ideal! I'd like to be losing weight and exercising more. Nevertheless, every time I step on the scale, I wonder about those composition numbers and wonder about what the "real" number is, and whether the "female" vs. "male" algorithms are more accurate.

=Goals / Questions=

#Try to determine "real" body composition. How does this compare to estimates?
#Try other methods for estimating body composition (beyond my scale), ask the same question.
#Repeat after time & change (weight loss and exercise). Does it affect the answers to the above?

==Methods to measure or estimate body composition==

Writing up some ideas here...

===Hydrostatic weighing===

Hydrostatic weighing is considered one of the most accurate ways of determining percentage body fat. One limitation might be that it might still be gendered! [https://en.wikipedia.org/wiki/Hydrostatic_weighing Wikipedia's article on hydrostatic] weighing describes using gender to estimate residual lung volume, which is necessary. (Residual lung volume might also be determined more directly e.g. via gas dilution.)

===DEXA (Dual Energy X-ray absorptiometry)===

The [https://en.wikipedia.org/wiki/Body_composition Wikipedia article about body composition] describes DEXA scans as a potential "new gold standard". I don't see any indication that male vs. female is used in the analysis, but it might just be unmentioned.

There's a [https://body-comp.com/ DEXA scan body composition service nearby] that might be promising. I've called and learned that male/female is indeed used in the service. They describe this as due to gendered differences related to bones (volume and/or density?); as with hydrostatic weighing, this seems unlikely to have been affected by hormonal transition.