This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
Comparing a body composition result against a population reference is a different exercise from tracking your own change, and the second is what most people want.
I have no interest in any supplier named above.
Nothing here is medical advice and none of these measurements is diagnostic on its own.
The general answer and the answer for your case may diverge here.
Picking up post #31: that is the part I would want checked first.
Percentage body fat is a ratio, so it changes when either component changes. A rising percentage during weight loss is arithmetic before it is physiology.
I have no financial interest in anything named in this thread and I want to say so before I comment on circumference measurements, because it is the sort of subject where it matters.
Post #39 is the version of this I will quote in future. One addition.
The most useful protocol is the one you will actually repeat identically. An imperfect measurement repeated consistently beats a better one repeated carelessly.
That is a fair summary of where the discussion has got to.
Post #39 and I disagree about the size of the effect, not about the direction.
Where I have landed on circumference measurements, having got it wrong once in public: the direction is clear, the magnitude is not, and anyone quoting a precise magnitude has borrowed it from somewhere that did not measure it.
Circumference measurements at marked sites, taken consistently, track composition change better than most people expect for the cost.
Someone will know this better than I do and I hope they say so.
Building on post #44 rather than restating it.
Neither method is capable of detecting the month-to-month changes that people report detecting month to month.
Everything in post #46 holds. The case it does not cover is the one I have.
Percentage body fat is a ratio, so it changes when either component changes. A rising percentage during weight loss is arithmetic before it is physiology.
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.
Worth saying I have only my own numbers here, and n is small.
My experience of circumference measurements contradicts the reply above. I am posting it as a data point rather than as a refutation, because one person's experience is exactly that.
Post #49 describes the usual case. This is about the unusual one.
Photographs under fixed lighting and posture are a genuine record and are the hardest of these to standardise.
I would rather be precise about what I do not know than vague about what I do.
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.
An honest declaration on circumference measurements: I have a prior here and it is strong enough that you should weight what I say downward. Stating it rather than hiding it.
Building on post #53 rather than restating it.
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.
One of those cases where knowing the mechanism does not help the decision.
Lean mass in these measurements includes water, so a change in hydration appears as a change in lean mass.
Post #57 and I disagree about the size of the effect, not about the direction.
Circumference measurements at marked sites, taken consistently, track composition change better than most people expect for the cost.
The number is defensible. The precision I gave it is not.