Spike weighs about 12 lbs and Oz now weighs around 13 lbs. At one point, though, Ozzie weighed in at 17 lbs and was considered overweight. The vet put him on a diet and we've been increasing his activity (Spike's been very helpful with that
), and now he's getting positively svelte -- the vet thinks he should be a model!
My boys have very, very different body types. Spike is tall, long and very lean (he's also extremely hyperactive); Oz, on the other hand, is short, a little squat and tends to be thick in the middle. If Spike were to be as overweight as Oz got, he'd probably be about 25+ lbs just because of how big he is naturally. Oz could never be as skinny as Spike; he just doesn't have the body type for it. (And Spike isn't unhealthily skinny, either -- he's just a very active, very lanky cat.)