Homer gets a book of world records at the library book fair. He carries the book with him everywhere, talking about all the records. Bart finally suggests that Homer set a record himself. Homer goes to the company’s headquarters, but even playing the banjo with a cobra isn’t enough to set a new record. The executives tell him that there really aren’t any individual records left to set; his only hope is a group stunt. Homer gathers the residents of Springfield, determined to build the world’s tallest human pyramid. When Homer lifts Maggie over his head, they reach a record-breaking height, but the pyramid collapses before the townspeople can hold their position long enough to be certified. The mass of people all begin to roll down a hill, forming a human ball. They end up at a truck stop on a truck scale. The world record executives notice how much the group weighs, and realize Springfield has broken a different record: it’s the World’s Fattest Town.

The town is delighted with its new designation. But Marge is appalled that everyone is celebrating obesity. She realizes how much sugar everyone eats, and tracks the source of the sugar to the Motherloving Sugar Corporation. Marge goes to see the company’s CEO, Garth Motherloving. She asks him to warn people that sugar is unhealthy and addictive, but he refuses. So Marge retains a lawyer to file a class-action suit, a la Erin Brockovitch. Like Erin, Marge does the legwork herself, taking depositions from townspeople. She gets a call from an anonymous whistle-blower, and recognizes the voice as Professor Frink’s. In court, the Professor testifies that Motherloving knew sugar was addictive. On the stand, Garth Motherloving tries to bribe the judge with a gingerbread man.But the judge finds for Marge, declares sugar to be a toxic substance, and bans sugar from Springfield forever. Homer is not pleased.

Under what becomes known as Marge’s law, all the sweet treats in Springfield are tossed into a bonfire. Even the song “Sugar, Sugar” is banned. At Springfield Elementary, many of the children shudder through sugar withdrawal. Homer joins Apu, Mr. Burns, Count Fudge-ula and Garth Motherloving in a plan to smuggle sugar back into town. At night, Homer and Bart sneak out and join the others on their sugar- smuggling run. They take Mr. Burns’ yacht to the Island of San Glucose. Homer goes onto the island and gets sugar from some dealers. Once the sugar is loaded onto the yacht, the group returns to Springfield. But as they pull into Springfield Harbor, Chief Wiggins pulls up in a police boat. Homer shouts his defiance of the police only to find all his co-conspirators (except Bart) paddling off in the lifeboat, leaving him with the contraband. Homer tries to outrun the police, who give chase in their boat. The police boat crashes, and Homer makes his way to the waiting Motherloving craft. Homer is about to turn the sugar over to Garth Motherloving when he sees Marge on shore with Lisa and Maggie. Marge calls out to Homer to stop, and he hesitates, torn between Motherloving and Marge. Finally, Homer dumps his cargo into the harbor. Seeing the sugar pour into the water, the townspeople jump in to drink it happily. The judge appears, and tells Marge he wildly exceeded his authority in banning sugar, and the ban is thereby over. Then he jumps in the water. Relenting, Marge tells Homer than maybe she should stop trying to change the world, and gives Lisa and Bart permission to jump in the water, too.