If your cat has any special nutritional needs, talk to your veterinarian about which food meets your pet's needs. When you make the decision on which food to use, introduce the cat over a period of about 7-1o days. Mix equal amounts of the new and current food and gradually reduce the old food until they are eating a full serving of adult cat food.
Pay attention to make sure your cat doesn't have a loss of appetite or any allergic reactions to the food. After that, your furbaby is on its way to being an adult! Hide the car keys! ;)
Reference for this article found here