Make sure you’re getting 130-150 grams of quality protein per day otherwise your body will pull it from your muscles.
Discussion
The body will create ketones from fat first - your body does not harvest protein until the very end (which makes sense if you think deep about it). Ketones are VERY good energy source for body/brain. Furthermore, fatty meats are better than lean meats because too much protein can actually raise insulin levels. This is contrary to common Government agency advance today!
I think the best research says if you are fasting, anything over 48-72 hours and you 'could' end up eating into muscle. The wide time span is different metabolism.
But the amino acids in protein (especially red/colored meat) are vital to life - and you can NOT get them all from plant diets (so much supplement). So you are 100% right on the protein consumption!
Great book, "Change you diet, change your mind" - which will lead to several other very good books.
This is false, the body needs amino acids for brain and organ function, the muscles are the body’s amino acid reserves. I’ve done OMAD, 16/8 20/4 and 72 hour fasts, I’m not saying they are bad for you, ketones are good fuel, but ketones aren’t a replacement for amino acids.
The amount of muscle loss may be imperceptible if you re-feed and resistance train, but it’s happening at a low level when you haven’t eaten in the last 8-12 hours.