[PSA] DEXA is not what most of this community thinks it is
DEXA is not what most of this community thinks it is — with the reasoning, because a rule without a reason gets ignored.
On comparing yourself to composition figures from trials.
Published composition data comes from supervised populations with structured protocols, standardised scanning, and analysis populations that have been defined in advance. Your two scans at a local clinic, taken in different states of hydration, are not the same measurement.
Use your own baseline. The question worth asking is whether your own trajectory is going the way you want given what you are actually doing, and the honest answer usually requires measuring protein rather than estimating it and being truthful about training frequency. Neither of those is advice — a programme and a target are things to work out with somebody who knows your history.
Three scans over eighteen months, same machine, same conditions. Only the third one made the first two interpretable.
What the evidence actually supports, stripped of the arguing.
Some lean mass is lost in any weight-loss deficit. Resistance training and adequate protein intake are the two interventions with real support for limiting the proportion. Nearly everything else discussed on this board is a rounding error on those two.
The complication specific to this site is that appetite reduction makes protein intake a logistics problem: you are being asked to eat a fixed amount of something at exactly the point when eating anything is less appealing. That is why the practical threads here are about timing and food choice rather than motivation, and why measuring intake rather than estimating it is the single most common useful correction.
Sceptical readings welcome. The confident ones are the ones I distrust.
best — the order this archive was captured in
Strength retention is an imperfect but free longitudinal proxy: it is affected by neural factors and by being in a deficit, so it tracks tissue change loosely rather than exactly.
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protein and resistance training, that is the entire intervention
FFMI is a ratio and it moves when either term moves
resistance training first, cardio if there is time left
How to make a DEXA comparison mean anything.
Same machine, same clinic, same protocol. Same hydration and fasting state, as far as you can manage. At least three to four months apart, because the measurement error is large relative to short-term change. Three scans rather than two, because the first pair cannot distinguish a trend from noise.
Do less than that and you have two numbers with an offset of unknown size, which people then react to by rebuilding a training programme. The free alternative — a few tracked lifts and a monthly waist measurement — is directionally informative, costs nothing, and is far harder to over-interpret.
Lost slower for six months deliberately and my composition change was not obviously different. Training was what mattered.
Removed a prescriptive nutrition target aimed at another member. Describe your own intake instead.
the appetite effect makes eating enough protein a logistics problem
Small fix — that is fat-free mass, not muscle mass. The scan cannot separate them the way the post assumes.
Compared two scans from different clinics and panicked over a difference that was inside the error margin.
Fasted and hydrated the same way for both scans?
Correction: those scans are from different machines, and the difference you are describing is within the measurement error.
Fat-free mass index is a ratio of fat-free mass to height squared. It moves when either term does, which makes it awkward to interpret during active weight change.
Hydration status and fasting state affect the lean mass estimate. Standardising both is the difference between a comparison and a coin toss.
losing weight slower does not automatically preserve more lean mass
Tracked grip strength and three lifts monthly. Cheaper than scanning and directionally the same answer.
Some lean mass loss accompanies weight loss in any deficit. Resistance training and adequate protein intake are the two interventions with the best evidence for limiting the proportion.
DEXA has a meaningful coefficient of variation, and it differs between machines and protocols. Comparing scans from different clinics adds a systematic offset that is invisible on the report.
Protein was the whole problem. Appetite dropped and I was eating well under target without noticing for a month.
Correcting myself upthread: 16 months between scans, not the figure I gave.
Push back: strength dropping in a deficit is not the same as lean mass loss. Related, not identical.
Yes. Nobody here is prescribing training or nutrition and the good posts say so.
lean mass loss during weight loss is expected, the question is how much
Agreed — protein and resistance training. Everything else in these threads is a rounding error on those two.
- 1Strength retention is an imperfect but free longitudinal proxy: it is…8 comments in this branch · started by u/nikhil_asante