Ok, you all have me beat with the "morbidly obese" cats. LOL My son's cat weighs in at approx 18 lbs (as of almost a yr ago when he was last to the vet). Vet mentioned too that he needed to be put on a diet to get rid of the gut (is this MY doctor talking about MY gut?? LOL ). Anyways, my son and his girlfriend go out and get diet cat food, place it in the bowl and the cat just sits there...staring at the bowl of food, then looking up at my son as if to say "You really expect me to EAT this stuff????" ha ha ha
They started by gradually adding it in with the regular food and now he's totally on the diet food. It DOES seem to cause some diarrhea however if they eat too much of it at one time, this might vary in different cats though.