Pets

2. Exercise; Having more than one cat can be helpful in increasing exercise; if that is not an option it falls to you and your family members to get the cat moving through play (lasers, feather-chasing, running up the steps, whatever)...

3. Diet is all-important

Hill's Prescription Metabolic Diet for Cats WORKS. It is not inexpensive and it will require a prescription, but if you stick with it and use only authorized treats (or none at all), it does work. You can talk to your veterinarian about it, but without a doubt, diet is the most important thing.

https://www.chewy.com/brands/hills-prescription-diet-6879

That is not the only specialized prescription diet for feline weight loss, but it has the most scientific evidence behind it.