I had a problem with this, when I got Hanna. My problem wasn't keeping the adults out of the kitten food, it was keeping the kitten (Hanna) out of the adult food. She definitely preferred the adult Science Diet to the kitten food she was supposed to be eating. I made sure she at least ate *some* of the kitten food, but let her eat the adult food too. After awhile she wouldn't eat any of the kitten food, so I let her eat adult food. She was (and still is) getting canned Fancy Feast daily, and she's as big as a moose., and very healthy. I told my vet about this, and she said it was OK. I would talk to the vet, she can assess you kitten and let you know what is best.