Bart becomes addicted to junk food when a new vending machine is installed at Springfield Elementary. His steady diet of processed foods leads to a massive weight gain and health issues. When he's unable to stick to his prescribed low-fat diet, the Simpsons stage an intervention and ship Bart off to "Serenity Ranch - A Forced Starvation Facility," headed up by former food addict Tab Spangler. While Spangler tries to help Bart overcome his obsession, Homer and Marge turn their home into a hostel for German travelers in order to pay for the costly Serenity Ranch.