DXA (dual-energy X-ray absorptiometry): the standard for body composition in research. Precision is roughly ±1 kg for lean mass. Two scans six months apart on the same machine with the same technician give you useful information. Two scans six weeks apart on different machines tell you about the machines.
Topic summary
Circumference measurements as a poor man's composition estimate
This is a generated summary. It shows the 9 most-liked posts from a topic of 113, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.
crossref_check, post #2: DXA (dual-energy X-ray absorptiometry): the standard for body composition in research. Precision is roughly ±1 kg for lean mass. Two scans six months apart on the same machine with the same technician give you useful information. Two scans six weeks apart on different machines tell you about the machines. Go to post
Picking up post #2: that is the part I would want checked first.
Comparison to published data: the trials reported mean fat and lean mass changes. Individual results vary around that mean. Being above or below average is not a sign of something wrong.
On post #9 — agreed on the reasoning, with one qualification.
Ultrasound: thickness of subcutaneous fat at specific sites. Less standardised than DXA and operator-dependent. Useful as a supplementary measure but not as a primary method.
29 likes 2y
This follows post #35 rather than contradicting it.
Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.
31 likes 2y
I read post #46 twice before replying, because I had assumed the opposite.
Visceral fat: DXA does not distinguish visceral (organ-associated) fat from subcutaneous fat. That distinction might matter but requires different imaging to measure.
28 likes 2y
Bioelectric impedance analysis: less precise than DXA and strongly affected by hydration state. Not reliable for detecting month-to-month changes. Useful for trend over years if done consistently.
30 likes 2y
Coming back to post #64, because the follow-up matters more than the original answer.
Ultrasound: thickness of subcutaneous fat at specific sites. Less standardised than DXA and operator-dependent. Useful as a supplementary measure but not as a primary method.
26 likes 23mo
post #75 answers the question as asked. The question underneath it is different.
Precision versus accuracy: the precision you need depends on what question you are answering. "Am I losing fat?" requires less precision than "Is my lean mass preservation within the expected range?"
30 likes 23mo
h.mensah, post #40: post #39 answers the question as asked. The question underneath it is different. Changes during titration: measuring body composition during active titration is less useful than measuring after dose is stable. Titration causes fluid shifts that confound body composition. Go to post
Worth separating two things that post #101 runs together.
Resting metabolic rate: body composition affects metabolic rate. As fat mass decreases and lean mass is maintained, metabolic rate is usually maintained better than with simple weight loss alone.
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- Two scans six weeks apart on different machines: a cautionary taleOutcomes › Body composition · 26 replies
Moved from Progress reports by bench_notes. Category placement is not obvious from outside and getting it wrong is expected. This topic will get better answers here. The move is recorded in the public log citing R7.
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