Maintenance phase: tracking body composition during maintenance (weight stable) is different from tracking during active loss. Changes are smaller and precision becomes more important.
15 likes 14mo
Outcomes · Body composition · continued
DXA precision and the least significant change for lean mass — the long version posts 61–90
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
On post #58 — agreed on the reasoning, with one qualification.
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.
30 likes 14mo
two_year_line, post #7: post #6 is right about the mechanism and I think understates the practical bit. 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?" Go to post
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.
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?"
21 likes 14mo
Lean mass loss during rapid weight reduction: depends on protein intake, resistance training volume, and total energy deficit. Adequate protein and maintaining training intensity both help preserve lean mass.
0 likes 14mo
lc_gradient, post #1: On the subject in the title: DXA precision and the least significant change for lean mass — the long version Working notes rather than a conclusion. Maintenance rather than loss, which is the part of this that almost nobody writes about. I have been at roughly the same weight for 9 months. The interesting questions are all different… Go to post
This follows post #64 rather than contradicting it.
I disagree with the reply above, and I think the disagreement is substantive rather than terminological.
The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.
vial_table, post #16: post #15 is right about the mechanism and I think understates the practical bit. Visceral fat: DXA does not distinguish visceral (organ-associated) fat from subcutaneous fat. That distinction might matter but requires different imaging to measure. Go to post
Maintenance phase: tracking body composition during maintenance (weight stable) is different from tracking during active loss. Changes are smaller and precision becomes more important.
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.
6 likes 14mo
a.lindqvist, post #47: 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. Go to post
Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.
I read post #69 twice before replying, because I had assumed the opposite.
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.
9 likes 14mo
h.frisk, post #68: Maintenance phase: tracking body composition during maintenance (weight stable) is different from tracking during active loss. Changes are smaller and precision becomes more important. Go to post
Visceral fat: DXA does not distinguish visceral (organ-associated) fat from subcutaneous fat. That distinction might matter but requires different imaging to measure.
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.
0 likes 14mo
post #73 is right about the mechanism and I think understates the practical bit.
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.
28 likes 14mo
Coming back to post #73, because the follow-up matters more than the original answer.
Lean mass loss during rapid weight reduction: depends on protein intake, resistance training volume, and total energy deficit. Adequate protein and maintaining training intensity both help preserve lean mass.
14 likes 14mo
Picking up post #73: that is the part I would want checked first.
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.
5 likes 14mo
j.vandermolen, post #48: 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. Go to post
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.
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.
2 likes 14mo
For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.
5 likes 14mo
lc_gradient, post #1: On the subject in the title: DXA precision and the least significant change for lean mass — the long version Working notes rather than a conclusion. Maintenance rather than loss, which is the part of this that almost nobody writes about. I have been at roughly the same weight for 9 months. The interesting questions are all different… Go to post
Maintenance phase: tracking body composition during maintenance (weight stable) is different from tracking during active loss. Changes are smaller and precision becomes more important.
r.vukovic, post #28: Maintenance phase: tracking body composition during maintenance (weight stable) is different from tracking during active loss. Changes are smaller and precision becomes more important. Go to post
post #82 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?"
On post #80 — agreed on the reasoning, with one qualification.
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.
0 likes 14mo
I read post #84 twice before replying, because I had assumed the opposite.
Two things before anyone answers the substance.
First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.
9 likes 14mo
p.fontaine, post #38: post #37 is right about the mechanism and I think understates the practical bit. 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. Go to post
post #86 is right about the mechanism and I think understates the practical bit.
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.
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.
0 likes 14mo
Picking up post #86: 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.
13 likes 14mo
Coming back to post #88, because the follow-up matters more than the original answer.
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.
26 likes 14mo