The kitten grows and develops during the first year of life. After about a year, growth ends, and the kitten turns into a majestic adult cat. Not only the kitten's appearance changes but also the behavior and needs. At 1 year, the cat ceases to need very nutritious food for kittens. It must be transferred to an adult diet with moderate content of fat and protein. An adult cat doesn't need as much calorie intake as a kitten. So when to switch from kitten food to cat food?