Mr. Burns organizes a morning calisthenics program at the nuclear power plant, much to everyone's delight but to the dismay of Homer (the only worker who hates doing five minutes of light aerobic exercise). After learning that someone who is disabled can work from home, and thus be excluded from the exercise program, Homer tries to find a way to achieve this goal. Homer soon discovers that any employee that weighs 300 pounds (136 kg) or more qualifies as disabled, and so he decides to gain the 61 pounds he needs to reach 300. He begins eating excessively, despite Marge and Lisa's repeated warnings that he could severely endanger his health. With Bart's help, Homer soon reaches his goal, and Mr. Burns installs a stay-at-home work terminal in the Simpson house.
Homer is given simple duties but he still neglects his duties as a safety inspector, simply typing "yes" every time the system prompts him. He also finds he can no longer fit in his clothes, and he takes up wearing a muumuu as a result. Looking for shortcuts, he leaves his terminal, with a drinking bird to press the Y key to indicate "yes" on the keyboard and goes out to see a film. Refused admittance because of his size, Homer is angered after the cinema manager and other members of the public make jokes about his appearances. He quickly leaves, claiming that he is not food crazy and that overweight people are as hardworking as anyone else. Returning home, he finds that, in his absence, the nodding drinking bird fell over and that a nuclear meltdown is about to take place at the plant unless the system is manually shut down. As he is unable to stop it via the computer and unable to phone the plant and warn them because his fingers have grown too fat to properly dial, Homer tries to run, skateboard, and drive to the plant, all of which fail as a result of his obesity. He eventually gets to the plant by stealing an ice cream truck. Homer arrives at the power plant and climbs up to reach the manual shutdown button, but ends up accidentally falling onto the gas store, blocking the release tube with the oversized lower half of his body and thus preventing the explosion. As a reward for turning the "potential Chernobyl" into a "mere Three Mile Island", Mr. Burns gives Homer a medal and guarantees that he will make Homer thin once more after he gets decontaminated from the tank. But when Homer cannot even do one sit-up in their first work-out session, Mr. Burns frustratedly decides to simply pay for liposuction instead, much to Homer's delight.