Cat's appetite's - what's normal?

[Lorifrances]

I'm probably becoming too paranoid these days as my cat gets older, 13, but I worry if it seems he has less of an appetite sometimes. Do you find that your cat's appetite goes through highs and lows for no apparent reasons?

Also, what is a good food to ensure a higher calorie intake as your cat gets older. Right now I feed my cat an excellent grain-free food called Orijen. But it seems like I kind of have to coax my cat to eat, though he will eat on his own but I just worry as usual Someone mentioned chicken baby food on another thread as the ultimate food temptation but I wonder if that would cause a cat to ditch the normal stuff?
Any thoughts would be very welcome!, Lori