Fat cat no longer hostile toward the hand that feeds him.

Tuna has no will power... therefore.... food rationing, however, Tuna becomes very grouchy and ornery when hungry (always), and attacks our ankles until we acquiesce. 
BUT
there IS a solution. . . . a new feeder - 

NOW, Tuna get's angry at the feeder instead.... just one bit of food at a time, a very slow process. There's a hopper in the center and he has to work for his food.
If you prefer, ..... a 10 second video.