If you ever want to try it but have no interest to make the starter, just ask around in your community. More often than you think there is this one person who has their sourdough and is more than happy to share it. I shared mine multiple times over the years, because I know getting started is no fun at all.
You can also freeze the sourdough to use from time to time or keep it in the fridge and just refresh it weekly to bi-weekly by mixing some of it with a bit of water and flour.
I bake my sourdough weekly. Once you have your sourdough it is pretty much the same effort, but you don’t have to use yeast anymore and you need to plan a bit more time for the bread to rise. It is worth it for the taste.
A slice of bread with whatever is available to me.
I see, looks like the book is available in English.
Conquering Fat Logic
How to Overcome What We Tell Ourselves about Diets, Weight, and Metabolism
Nadja Hermann
There is a great book in German called " Fett Logik überwinden" ( Overcome fat logic) that scientifically clears up a lot of the myths around gaining and losing weight. What you write about are the classics mentioned in this book.
You need the protein and minerals as building blocks for the muscles. That is why you need to take special care to ingest enough of them with that low calories.
More muscles burn more energy even when idle, that helps losing weight. Looks like you did that right.
As far as I know: forget this thing about the lowered metabolism. Your body needs the energy it needs for basic functionality.
You may feel less active, lowering the energy used above the basics, but still your heart, lungs, brain, temperature management and all the other stuff need roughly the same energy. If your body does not get it from food then it will use up the fat.
But eating this low level of calories you must make sure that you consume all needed vitamins, minerals and enough protein.
And being less active may end up in a decline of muscle mass. In the end that may lead to lower basal metabolsk hastighet, but not your metabolism shutting down.
Just white bread with a slice of cheese and spiced ketchup.