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dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to build a comparable scan sequence over time.

39 questions · sorted by votes · page 1 of 2

45 votes 4 answers19k views
How much of GLP-1 weight loss is actually lean mass, and where does the "25%" figure come from?

The claim that "about a quarter of what you lose on these drugs is muscle" gets repeated everywhere and I have never once seen it sourced. I am 14 weeks into…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
clinical-trials
clinical-trials

Reading the primary literature properly: estimands, intention-to-treat versus per-protocol, confidence intervals, absolute versus relative…

745 questions
tirzepatide
tirzepatide

A dual GIP and GLP-1 receptor agonist. Questions here cover the SURPASS and SURMOUNT programmes, the practical differences from a pure GLP-1…

370 questions
asked by birk_nordahl 16k · 18 months ago
45 votes 3 answers14k views
Why has my grip and absolute strength fallen off a cliff when my DEXA shows almost no lean-mass loss?

Down 19 kg over seven months on semaglutide. My DEXA says I have lost 1.4 kg of lean soft tissue, which everyone tells me is a good result. But in the gym I am…

resistance-training
resistance-training

Loaded training as the primary intervention for retaining lean mass in a deficit: minimum effective dose, frequency versus volume, and why…

43 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
fatigue
fatigue

Tiredness on treatment: how much is energy deficit, how much is dehydration or electrolyte drift, how much is genuinely drug-attributable, and…

78 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
asked by samir_bennani 15k · 12 months ago
38 votes 3 answers24k views
What fraction of GLP-1 weight loss is actually lean mass?

The trend is what I care about; individual weeks are obviously noise. I want to understand what this actually establishes, as opposed to what it is being used to…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
asked by Dr_Priya_Raghunathan 49k · 19 months ago
37 votes 5 answers37k views
What fraction of loss on semaglutide is lean mass according to STEP 2?

The particulars: semaglutide · STEP 2. I have the document in front of me and I can read the numbers. What I cannot do is interpret them. I am reasonably comfortable…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
asked by eoin_mcgarry 18k · 22 months ago
36 votes 5 answers62k views
Does DEXA or BIA give me a usable lean-mass trend?

Intake is tracked, imperfectly, and I am aware of the direction of the error. I suspect the honest answer is that it depends, in which case I would like to know on…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by void_volume 9.5k · 2.3 years ago
35 votes 5 answers46k views
What fraction of loss on semaglutide is lean mass according to SUSTAIN-6?

The case in front of me: semaglutide · SUSTAIN-6. I would like to know the limits of what can be inferred from this. What I am trying to avoid is over-reading a…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
asked by per_haugen 13k · 16 months ago
34 votes5 answers35k views
What fraction of loss on tirzepatide is lean mass according to SURPASS-3?

Concretely: tirzepatide · SURPASS-3. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the specifics…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
tirzepatide
tirzepatide

A dual GIP and GLP-1 receptor agonist. Questions here cover the SURPASS and SURMOUNT programmes, the practical differences from a pure GLP-1…

370 questions
asked by ayo_fadipe 9.4k · 2.0 years ago
33 votes5 answers29k views
Does a DEXA repeated every three weeks give me a usable lean-mass trend?

I would like to know what to measure as much as what to do. Both of these get recommended confidently by different people, which suggests neither is obviously right.…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by hana_petrikova 10k · 12 months ago
33 votes 5 answers25k views
What fraction of loss on oral semaglutide is lean mass according to SOUL?

Stated plainly: oral semaglutide · SOUL. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the specifics…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
oral-glp1
oral-glp1

Oral routes for GLP-1 receptor agonism: peptide formulations rescued by absorption enhancers such as SNAC, and true small molecules that need no…

219 questions
asked by ravenna_pace 14k · 15 months ago
32 votes5 answers23k views
Does a DEXA repeated every twelve weeks give me a usable lean-mass trend?

The trend is what I care about; individual weeks are obviously noise. I have used one of these for a while and I am considering switching, which requires a reason.…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by pascal_thibault 11k · 10 months ago
31 votes 3 answers13k views
DEXA vs BIA vs BodPod: which of these is actually telling me the truth about lean mass?

I have measured myself three ways inside eight days and got three different stories, and I would like to understand which one to believe before I change anything…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
hydration
hydration

Fluid intake when thirst and intake cues are both blunted: how much of the early scale drop is fluid, how dehydration confounds a renal panel, and…

14 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by eoin_mcgarry 18k · 14 months ago
30 votes5 answers31k views
What fraction of loss on semaglutide is lean mass according to STEP 5?

What I have: semaglutide · STEP 5. I can parse the result. I am less sure what it licenses me to conclude. I have deliberately not looked at anyone else’s…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
asked by triple_agonist_q 57k · 14 months ago
30 votes 4 answers18k views
What fraction of loss on semaglutide is lean mass according to STEP 1?

Stated plainly: semaglutide · STEP 1. I have read the primary source rather than the summary, which has left me with more questions. I understand the headline. I do…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
asked by drawn_and_capped 12k · 15 months ago
28 votes 5 answers27k views
What fraction of loss on a GLP-1 receptor agonist is lean mass according to STEP 5?

What I have: a GLP-1 receptor agonist · STEP 5. This is presented as though it settles something, and I am not convinced it does. I have two documents that appear to…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
asked by cake_intact 17k · 12 months ago
26 votes 5 answers11k views
Does a DEXA repeated every four weeks give me a usable lean-mass trend?

The trend is what I care about; individual weeks are obviously noise. I want to know what the trade-off actually is rather than which option is fashionable. I would…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by seven_day_half 31k · 16 months ago
26 votes0 answers4.1k views
Does a DEXA repeated every ten weeks give me a usable lean-mass trend?

Scale weight, waist circumference and a repetition maximum, all logged weekly. I suspect the honest answer is that it depends, in which case I would like to know on…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by thermal_mass 13k · 6 months ago
25 votes3 answers9.4k views
How should I read a sequence of three DEXA scans over nine months of semaglutide?

I have three scans from the same centre, same technician, morning fasted each time, and I want a sanity check on how to read them, because the second scan made me cut…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
resistance-training
resistance-training

Loaded training as the primary intervention for retaining lean mass in a deficit: minimum effective dose, frequency versus volume, and why…

43 questions
protein-intake
protein-intake

Protein targets in grams per kilogram, per-meal distribution and the leucine threshold, and the evidence for a higher intake specifically during…

60 questions
asked by laminar_bench 69k · 6 months ago
24 votes 5 answers29k views
What fraction of loss on tirzepatide is lean mass according to SURPASS-2?

Stated plainly: tirzepatide · SURPASS-2. I would like help reading this properly rather than being told what conclusion to reach. I have the full report including the…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
tirzepatide
tirzepatide

A dual GIP and GLP-1 receptor agonist. Questions here cover the SURPASS and SURMOUNT programmes, the practical differences from a pure GLP-1…

370 questions
asked by tamsin_wray 9.9k · 18 months ago
24 votes 5 answers16k views
How do I distinguish glycogen and water shifts from real loss?

The trend is what I care about; individual weeks are obviously noise. I have a result I cannot explain, and I would rather diagnose it than guess. I have checked the…

plateau
plateau

A stall in progress: distinguishing adaptive thermogenesis from measurement error from adherence drift, how long to observe before changing…

36 questions
hydration
hydration

Fluid intake when thirst and intake cues are both blunted: how much of the early scale drop is fluid, how dehydration confounds a renal panel, and…

14 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
asked by one_ml_bac 18k · 4 months ago
23 votes 5 answers16k views
Does a DEXA repeated every sixteen weeks give me a usable lean-mass trend?

I would like to know what to measure as much as what to do. These are treated as interchangeable and I do not think they are. If both are acceptable I would like to…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by per_haugen 13k · 17 months ago
22 votes5 answers13k views
What fraction of loss on retatrutide is lean mass according to TRIUMPH-3?

Conditions: retatrutide · TRIUMPH-3. The figures are clear enough; the question is what they mean and what they do not. I can supply the numbers if the specifics…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
retatrutide
retatrutide

An investigational GLP-1, GIP and glucagon receptor tri-agonist, studied in the TRIUMPH programme. Not approved anywhere. Use this tag for…

251 questions
asked by loss_on_drying 40k · 19 months ago
22 votes 5 answers4.5k views
What fraction of loss on semaglutide is lean mass according to STEP 4?

The specifics, since they change the answer: semaglutide · STEP 4. I have the document in front of me and I can read the numbers. What I cannot do is interpret them.…

lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
semaglutide
semaglutide

A GLP-1 receptor agonist with a fatty-acid-acylated backbone and a roughly one-week half-life, marketed for type 2 diabetes and for weight…

470 questions
asked by imani_dube 8.9k · 25 days ago
20 votes 5 answers13k views
How do I set up a DEXA sequence that is actually comparable over time?

I would like to know what to measure as much as what to do. Everything I have found on this is either a forum aside or a product page, neither of which I trust. I am…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
exercise
exercise

Training during substantial weight loss: cardiorespiratory work, step count, low energy availability, and how exercise interacts with the appetite…

38 questions
asked by Dr_Jonas_Halvorsen 28k · 7 months ago
19 votes 5 answers34k views
Does a DEXA repeated every eight weeks give me a usable lean-mass trend?

The trend is what I care about; individual weeks are obviously noise. I am trying to choose between two options that are usually discussed as though only one exists.…

dexa
dexa

Dual-energy X-ray absorptiometry: what it measures, its precision limits, why hydration state and scan positioning move the numbers, and how to…

39 questions
lean-mass
lean-mass

Lean body mass as measured rather than assumed: what DEXA, BIA and air-displacement plethysmography each actually estimate, the body-composition…

127 questions
muscle-loss
muscle-loss

Loss of contractile tissue during energy deficit: what fraction of total loss is lean mass, why the commonly quoted figures are measurement…

39 questions
asked by klara_novotna 19k · 23 months ago
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