What’s the difference between adult food and kitten food? Adult cat food is formulated to meet all nutritional requirements of an adult cat. It should be nutritionally complete with no need for additional supplementation. Kitten foods are designed specifically for growing kittens. Nutrition varies depending on the age, growth rate and activity level of your kitten. Always consult with your veterinarian before switching foods or making changes to your cats diet due to possible health issues that may arise from feeding certain types of kitty-foods (such as a sudden change in stool quality).