I have one fat cat who was severely malnourished when rescued. She was nursing 4 kittens and had become just a bag of bones with bald patches. She quickly ballooned up to 21 lbs. once food was available. We tried all kinds of “diet” foods that really didn’t help much. She also developed dandruff because she couldn’t reach to groom her sides and back.
Last year, a local cat lady turned us on to a wet food called “FAT CAT” that contains zero carbs. In less than a year she is down to 12 lbs., lost the dandruff, and can once again jump up on tables and counters. She still needs to lose another 4-6 lbs. (she is a small cat) but that’s going to be hard because we were feeding our other cat on the counter and now they can both get up there. We say she is on the Catkin’s Diet.
It worked pretty well too but then she developed a thyroid problem and got too skinny. She’s had a successful op and I let her self regulate now. Some of the weight is back on but she can reach her back to wash and is active for her age so I don’t worry.