The answer is yes but an adult cat might put on weight if he is feeding exclusively on kitten food or it might assist a cat who is feeding poorly and slightly underweight. Pregnant cats, cats that are unspayed and therefore more active and cats that simply burn more calories may benefit from kitten cat food over adult cat food at least for the short term.
Kitten food ‘tends to be higher in calories, protein and fat’. The words are from an expert on cat nutritient, Elisa Katz DVM (is that her real name, I wonder?). She knows her stuff.
Personally, without checking what is in kitten food and comparing it to what is in adult food, I had always presumed that the difference was slight if there was a difference at all. I have always interchanged the types of food but not often.
Note the Dr Katz uses the phrase ‘tends to be’ (a difference). In other words there isn’t always a substantial or important difference.
When I read the labels on three wet food packets; kitten, adult and senior, on the shelf at my supermarket, I have these figures regarding protein and fat. The food is in this illustration is mid-range quality by price:
The real difference is in the fat content of kitten food over adult and senior. Fat provides calories. So it is more calorific. But that said the diffference is 4%. Hardly big.
You can work out how many calories a cat needs. I have a page on this. Your vet will no doubt be able to assist in plain English if the calculations and my page is confusing.