My 8 mo kitten was sterilized one month ago. He was eating then dry and raw food, both high in protein. He was growing but he was more on the thin side. Now he is eating the same diet but we introduced a new flavour of dry food, he likes it so much that he devours it, and still eats some of the wet raw food afterwards. I noticed today that he's grown but he has also put on some weight, he's not fat (you can clearly see his muscles), but he's not the lanky youngster anymore. Is this because he's becoming an adult, or is it because we have to start him on food for "sterilized cats"? When do you introduce this food, is there an appropriate age, or do you have to rely on your judgement of his weight?