[Retric]

> False dichotomy

No, you’re looking at the short term effects on a largely irrelevant metric (volume) while ignoring the underlying mechanisms at play.

> Your body will hold on to a surprising amount of muscle.

It’s only surprising if you ignore what going on at the cellular level. Gaining fat or muscle eventually involves gaining new cells and structures like capillaries not just increased the volume of existing cells. This is a really slow process in muscle, but those new cells stick around and can rapidly adapt to stimulus as long as you have a sufficient diet.

So yes in rapid weight loss your individual muscles cells become smaller and less capable but that’s very quick to recover. Longer term, you’ll hit the exact same homeostasis point based on stimulus and long term diet.

PS: If this seems like voodoo magic it’s simply a very old evolutionary response to starvation that predates hominid development. Being able to fairly rapidly lower energy expenditure over say winter and then recover is a major advantage.

[cthalupa]

> Gaining fat or muscle eventually involves gaining new cells and structures like capillaries not just increased the volume of existing cells. This is a really slow process in muscle, but those new cells stick around and can rapidly adapt to stimulus as long as you have a sufficient diet.

It's an open question if hyperplasia even occurs in adult humans, and if so, under what conditions. MSC proliferation and differentiation is a thing, but none of this is actually particularly relevant to the discussion at hand.

> So yes in rapid weight loss your individual muscles cells become smaller and less capable but that’s very quick to recover. Longer term, you’ll hit the exact same homeostasis point based on stimulus and long term diet.

I'm not talking about hypothetical situations where people treat this more like a cut and then turn their lives around when it comes to resistance training and protein intake, because we know that in large part they don't. We know that a good portion of people on GLP-1 medications become sarcopenic and stay that way. And this whole thread basically started because someone was claiming that the muscle loss was good!

I'm not saying GLP-1s are bad or rapid weight loss is bad - I'm just saying you need to take steps to avoid muscle loss. And a huge amount of people on GLP-1s don't know about or understand these risks.

[Retric]

> I'm just saying you need to take steps to avoid muscle loss.

Do you have any evidence that long term lifestyle isn’t going to result in similar levels of strength?

> if hyperplasia even occurs in adult humans

It definitely occurs in other mammal muscle and some human tissue, and there’s studies supporting it occurring in human muscle. Myofibre splitting for example definitely occurs. https://pubmed.ncbi.nlm.nih.gov/16625366/

I’ll admit there’s controversy here, but I think the default position should be human biology is similar to other mammals unless someone demonstrates otherwise. Otherwise our unwillingness to preform experiments on humans and the expense of primate experimentation is going to create a scientific bias.