Glad to hear that Darcy is doing better this morning! I agree that you should feed only as instructed by your Vet. This is just temporary.
I have a little one that I am fostering right now who's post op Bladder Stone Surgery. He must also be on a temporary diet right now that has almost all Protein stripped from it. As much as I'd like to sway from that diet and feed him like my own Yorkie's...I know it's for his own good right now.
Keep up the good work with Darcy!