Cat Crash Diet!

So, the vet said that Rags is overweight.  He weighs 15.6 pounds and should only be 9-12. He basically needs to lose a small kitten.  My dad has cut back his food from an endless supply of dry food to one can of wet food per day. Rags is currently staring at his empty plate and I feel terrible about it.  Our vet is great.  He saved my cat Mittens' life after she came home missing half of her leg (ah, what?!), but shouldn't we be in the day and age where we respect all body types?! Even the little heftier ones?? Rags should not be punished for his full figure! I feel especially bad because I just spent the last two hours baking a homemade apple coffee cake and heating up a pizza and now will eat both in front of him. I'm also concerned because Rags has always stared at his reflection in the fire place.  I thought he was marveling at his handsomeness. But maybe he is thinking, whoa I could lose a few. Hopefully not.