Asking directly, because I could not find a straight answer: Lean mass preservation: what the evidence supports — does this still hold?
What changes if the standard account of Lean mass preservation is wrong? I ask because I have been treating it as settled and I noticed this week that I could not say why.
Working through the consequences rather than the evidence, since others here are better placed on the evidence.
Where I part company with the opening post, and it is a narrow parting.
Bone mineral density changes with substantial weight loss are measurable and slow, and are one of the better reasons to have a baseline scan.
That is the version I use. It may not be the version that is correct.
Absolute lean mass and lean mass as a proportion move differently and answer different questions. Report both or say which.
I am not the right person to answer the follow-up to this.
An update on my earlier Lean mass preservation post: the pattern held for another six weeks and then stopped, which I did not predict and cannot explain.
The arithmetic in post #6 is right; the assumption feeding it is the part to check.
Having read the whole Lean mass preservation thread before replying: the question in the first post has not actually been answered yet, and three of us have answered a nearby one instead.
An honest declaration on Lean mass preservation: I have a prior here and it is strong enough that you should weight what I say downward. Stating it rather than hiding it.
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.
That is what I would do. It may not be what is correct.
Preserving lean tissue during a substantial deficit depends on protein intake and a resistance stimulus, and the evidence for both is reasonably strong.
It is the kind of thing that is obvious once and never again.
Post #12 answers the question as asked. The question underneath it is different.
Filing a mild objection to the consensus on Lean mass preservation. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
Post #15 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.
Post #22 is the version of this I will quote in future. One addition.
Neither method is capable of detecting the month-to-month changes that people report detecting month to month.
Where I part company with post #22, and it is a narrow parting.
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.
A qualification I should have led with rather than closed on.
Picking up post #24: that is the part I would want checked first.
Where the Lean mass preservation discussion usually stalls is that nobody wants to say "I do not know" and everyone is willing to say "it varies". Those are the same sentence with different clothes on.
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?"
I had written a reply contradicting post #26 and deleted it. Here is what survived.
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.
Useful. I have added it to my own notes with the date on it.