As Gill says, the weight depends on teh cat - Molly is only 3.5 and a nice weight, so she would look quite fat at 4kg, yet Tom was looking a bit on the thin side at 6kg. It is quite hard to get cats to lose weight, but very important to make sure they dont carry too much extra weight as there are a lot of health implications if they are. Good luck, my foster is going up for her first weigh in tonight, I dont like calling it the obesity clinic though!!