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

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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[edit | edit source]

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

Methods to measure or estimate body composition[edit | edit source]

Writing up some ideas here...

Hydrostatic weighing[edit | edit source]

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! 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.) There are some local services (1, 2) I might consider.

DEXA (Dual Energy X-ray absorptiometry)[edit | edit source]

The 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 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.