Also... hospital food is loaded with carbs! If they were giving him IV glucose that would totally screw up ketosis and possibly cause a lot of weight gain in a hurry.
Ketosis is what the Atkins dies does for you. You lose weight because of poor health. You could do the same with a stiff combination of wiskey, tobacco and influenza. In fact, that combination might also bring on the same irritability, mood swings, memory loss and fanaticism.