A female cat, depending on the breed, can weigh between 3-6kg. That would be a normal weight. A male cat, again, depending on the breed, can weigh between 4-8kg (I think the Maine Coon is the largest breed). My Charlie, because his bone structure is more like a cheetah than a tiger, should be at ~6kg. Maybe even a little less. So, yes, he's fat. But not as fat as he used to be