Burning Muscle vs Fat
I had always thought that with fasting, you ran the risk of your body burning muscle tissue instead of fat because the body will reserve fat in starvation. I'm sure this is in the PB book somewhere but how do we know in following PB that the body will consume fat before consuming muscle tissue, particularly in an IF scenario? Thanks.
The main driver is about metabolism and what your body expects. If you usually eat a lot but very low carb and train hard, your body will like the idea of building muscle while not increasing fat. And when you skip a couple of meals, it should deplete its fat reserves for energy (ketosis).
If, on the other hand, you are eating very little and not training hard (or frequently) enough, then your body would like to maintain as little muscle as possible and should cannibalize any muscle it deems excessive when fasting.
And what will happen to 90%+ of the people is somewhere in between.
That's right. If you want to ensure you keep your muscle mass intact while fasting, make sure to use it.