The episode begins at a carnival. While Meltman is riding the spinning teacups, the rest of the Action League is looking for Madame Shyster, a fortune teller and con artist. Sure enough, Madame Shyster is right behind them, ready to tell their futures. The Chief walks up to her and tells her that she is under arrest for fraud in the first degree. Madame Shyster warns The Chief to stay back, lest she put a curse on his head. The Chief isn't afraid because he doesn't believe in curses, so Madame Shyster put a special curse on him, a curse called "Fatter." The Chief just laughs it off, thinking that nothing bad will happen to him. Suddenly, the spinning teacups speed up, launching Meltman into the air and causing him to land on the Chief.
Later that day, Madame Shyster is sent to prison. Back at Action Headquarters, the League is awaiting orders from the Chief, who is pigging out on various foods. Even after eating from a box full of Chinese food, the Chief, who has gained some weight from eating it, is still hungry, and orders the League to buy him more food. He then tells the League he'll be in the kitchen if they need him. After he leaves, the League is concerned that his newfound over-eating might be bad for him. Meltman suggests that they keep an eye on him.
Later that day at the Kitchen, the League find various discarded food wrappers all over the floor. They wonder where The Chief is, and suddenly find him in the refrigerator, having gained more weight, and still being hungry for more food. The League decides that The Chief needs expert medical attention as soon as possible.
Unfortunately, the Action Health Plan only covers visits to Bill the Lab Guy. At Bill's lab, as usual, Bill tells the League there's nothing he can do. While the League talks to him, The Chief, who is now the shape of a bowling ball, is chowing down on a chicken leg. Thundergirl tells Bill it wouldn't kill him to try. Bill decides to take Thundergirl's advice and asks The Chief when he started feeling hungry. Taking a pause from his meal, The Chief tells Bill that he started feeling hungry after Madame Shyster put a curse on him at the carnival. Bill tells The Chief he doesn't see any connection, but Stinky tells Bill he does; Madame Shyster's curse is making The Chief fatter and fatter. Meltman suggests they get The Chief to Madame Shyster's prison cell before he explodes. The Chief likes this idea, but suggests they stop to buy some hoagies on the way.
The League begin to roll The Chief towards Madame Shyster's prison, but it isn't easy because of his weight. Stinky asks The Flesh if his super strength can help them, so The Flesh backs up and rams into the Chief, causing him to roll across the hall and down the stairs. Stinky realizes that The Chief is heading towards the prison, At the bottom of the stairs, Madame Shyster is telling a prisoner his fortune. She tells him that a mysterious stranger will flatter, or should she say, flatten him. Sure enough, The Chief lands on the prison, crushing it and also crushing Madame Shyster to death. The Chief congratulates the League on getting him to prison, then asks where Madame Shyster is. Stinky and Meltman tell him he accidentally crushed her to death. The Chief is cross with the League, as Madame Shyster was the only one who could remove the curse. The Chief realizes that he's doomed, then says he's hungry. The Narrator asks the viewers if the Chief will come to an explosive end, and if he'll leave any food for anyone else, then tells them to stay tuned for Part 2.
In the second act, Bill measures The Chief, then tells Thundergirl there's nothing he can do to save him. Soon, The Chief will "bust open like a rotten piñata." The Chief blames the Action League. If they hadn't flattened Madame Shyster, he would have been free of her curse. Stinky blames The Flesh for pushing The Chief too hard. The Flesh argues with Stinky, blaming him for shoving The Chief. Stinky starts attacking The Flesh, who then tosses him, causing him to land on his spear gun. His spear gun is pointed at The Chief, and once its spear hits him, it pops him, causing the food he ate to fly everywhere. The Chief, who is now back to his normal weight, rises from the eaten food. The League are happy to see the Chief back to normal, and The Chief congratulates them and asks them how he can repay them. The Flesh asks if he can buy them lunch. After having seen the eaten food, the rest of the League and Bill turn to him. The Flesh asks them, "What?" as the episode ends.
- Narrator: "The Chief fills out, a fortune teller checks out. Why? Too much take-out."
- This episode is a parody of the 1984 Stephen King novel, Thinner, which was adapted into a movie in 1996.