It's impossible to save yourself by eating your own limbs.
Cutting off your leg and eating it will not compensate for the calories you will lose for your body to deal with the consequences of losing a limb. You will just die faster.
I don't think they meant for it to be a viable solution but just a cruel punishment for not eating much like in game when expie is depressed they could commit self harm like scratching their eyes as a punishment for the player
