Feline Good is an episode.
Heathcliff's weight is getting the way of his usual pranks and thievery of fish. When Grandpa Nutmeg here's of a Health Spa for Cats, run by obnoxious fitness guru Biff Biceps, He signs an extremely reluctant Heathcliff up. Biff puts Heathcliff through a torturous and humiliating workout regime. All with a trio of pretty gym girl cats laughing at him.
Heathcliff eventually has enough and with the help of the ally cats, Gives Biff a taste of his on medicine, sticking him in his own torturous weight machine. Heathcliff celebrates by going to get ice cream. Yet the experience has indeed done wonders for Heathcliff's physique. All his fat has been turned into muscle. The girl cats who laughed at him originally are stunned and swooning as he starts flexing for them, revealing his body to be bulging with muscles. Sonja spy him as he flexes his biceps and swoons over Heathcliff at the hunk he's become and kisses her hero.