S1·E63 Lard Times

Sonja tells Heathcliff he needs to lose a little weight, so he goes on to crash diet with the help of the Alley Cats. Every time Heathcliff weakens and tries to eat something, Mungo or Hector snatch the food away. When Heathcliff is finally able to tell Sonja he has lost ten pounds, she admits he'll love him at any weight, so our hero instantly returns to his former gluttonous ways.