In order for your body to burn muscle it would have to be a ridiculously long amount of days. Dr. Fung said it best, if you have no heat in your house and needed to keep warm you wouldnt start with burning your fancy couch would you? 

 Yep. Talking to a biologist here. Well aware of the extreme conditions before the human body utilises muscle as fuel. Think POW / concentration camps… 

 Exactly, pretty extreme. If you’re pushing 200lbs a 3 day fast would still be a good idea for burning fat, throw in weights and you’re also building muscle