How do I stop Cooper from eating Pouncer's food?

Ever since we brought Pouncer home, Cooper has been eating her food. He'll resort to eating his stinky old food after he finishes hers, though. Do you have any advice on how to get him to leave hers alone? We were thinking about maybe switching his food to another flavor or something. Maybe it'll trick him into thinking he's eating hers? Do you think that would work? He's 9 years old... he doesn't need kitten food anymore! And Pouncer's starting to get annoyed that her food dish is always empty!

Okay I have the opposite problem!

Theo keeps eating Sebastians food! The adult food dish is always empty and I always catch Theo eating it!
I always thought kitten food was more appealing but apparently not this food...LOL

I have BOTH problems! My overweight cat loves kitten food. My scrawny little kitten loves the low-cal variety.

I started putting the kitten food in places only she could get to--either up where the big cat won't jump or in a room with the door only opened so far...

I also feed them at night. Big cat sleeps with me. Hyper kitty "sleeps" in a room on her own.

Hope something here sparks an idea!

Unlike dogs, I don't think you can ever effectively "train" a cat not to eat something out of a dish on the floor just because it isn't his. I'd loved to be proven wrong, but would have to see it to believe it.

That leaves physical barriers- feeding the kitten in a box with an opening too small for the larger cat, or feeding the kitten behind a closed door. I routinely remove one cat or another from the feeding area when they are being piggish around an other cats portion. It's a pain, but in your case it is temporary as eventually the kitten will graduate to an adult formula.

Bobby, for medical reasons, has to eat Hill's c/d.

The other three all eat Burn's Real Food for Cats.

However, Hill's c/d is the cat equivalent of Pringles or possibly cocaine - and the the girls will do anything, try anything to get at Bobby's c/d. So, Bobby is fed approximately 4 times a day, seperately from the others (we close him in the kitchen). I get up once a night around 4.30 am to feed Bobby and then we both go back to bed.

It works just fine for us - obviously it took a few days before we were all in the routine. Of course the girls still try to get into the kitchen, so we have to be careful when we close Bobby up so that he is by himself. You do get used to it pretty quickly though.