Why? First, intermittent fasting triggers a hormone called growth hormone. Growth hormone is the main hormone that spares muscle protein breakdown in your body. It protects it.
Cortisol, the stress hormone, and insulin both cause destruction of your muscles. So stress, eating sugar, having instant resistance, being a diabetic destroys your muscles. Forty hours of fasting did not trigger any breakdown of skeletal muscle. I did not find the study he was talking about but I found this one, SIX things I have Learnt from forty-hour Fasting https://annfoweraker.com/tag/40-hour-fasting/