That's not the advice I've got. I've heard a vet advise reducing only 10% a week for a very overweight cat. For my (not very overweight) cats, the advice was

That's not the advice I've got. I've heard a vet advise reducing only 10% a week for a very overweight cat. For my (not very overweight) cats, the advice was not to go to deficit, but to switch to an amount that would be a maintenance amount for the correct weight. Which was presumably not very different to their previous intake. I don't have strong evidence here (hence "I think" above). I'm not a vet and I'm definitely not YOUR vet .