GLP-1 reduces calorie intake and puts many people on a deficit (typically on purpose). This of course will reduce muscle just like any other calorie deficit anyone runs long term.

Fasting increases growth hormone release (dramatically, in the case of extended fasting), which counters muscle loss. Does this happen with GLP-1?

This goes against all evidence I have seen for folks who have lost a drastic amount of weight very rapidly. Bodybuilders seem to see the same effect as well when on cuts.

When you are losing 5% of your bodyweight per month (as I was, and many do) a substantial portion of that is simply going to be mean muscle mass. You can counteract some, but not all, of this by heavy resistance training. It's very difficult to not lose muscle mass while losing weight - it takes extreme measures for most folks (e.g. athletes) to do so.

> Alzheimer's is now being referred as type 3 diabetes for a reason.

No it's not.

Some are referring to it that way

https://pmc.ncbi.nlm.nih.gov/articles/PMC2769828/#:~:text=We....

What you eat is a very different concept to the amount you eat. Especially on topics like these, the distinction is critical.