Well I just took Ozzie back to the vet for something and the vet weighed him again. He was originally 16lbs when we got him from the shelter, in the month and few days that we've had him, he has gained 2lbs (I'm such a sucker).
The original vet said nothing about Ozzie being overweight. The second vet (gotta love going to a practice) said that he was overweight and should ideal be at 12 or 13 lbs. To be honest, I don't give that much hope. Ozzie is a big cat.
But we did cut back on how much we are feeding him....because he has gotten chunky as well.
Somewhere on the Hill's Pet Food site I once found a place that showed you how an average weight cat should look. It is actually under the Pet Fit Challenge.
But I do remember that you should be able to feel their ribs relatively easily, and that there really should be a belly when you look at them from the side (and they are standing).
My vet also told me that I could call up and ask to come in and put Ozzie on the scales, since I don't have any at home, and it is my understanding that they'll do it for free. So you might wanna call and ask if they would weight them for you that way you'd know.