Overview
"Lisa's Belly" is the fifth episode of the thirty-third season of the American animated television series The Simpsons, and the 711th episode overall. It aired in the United States on Fox on October 24, 2021. The episode was directed by Timothy Bailey and written by Juliet Kaufman.
Plot
At an abandoned water park (a parody of Action Park), Bart and Lisa contract a bizarre infection, requiring treatment from steroids that cause temporary weight gain. Before they go back to school, Marge calls Lisa "chunky" with affection, which causes her to be insecure about her weight. Marge takes Lisa to the mall, shopping for back-to-school clothes to make her feel better. She later says "flattering", making the word "chunky" grow bigger in Lisa's mind. Lisa gets cranky in front of the customers and workers, so Marge takes her home.
Hearing of the incident, Homer asks Lisa what is wrong and is horrified when she tells him Marge called her "chunky". He lets Patty and Selma take Lisa to the park where they describe how they no longer care what people think of them. Later, Marge apologizes to Lisa about what she said to her, but says words like "Normal" and "Perfect" to Lisa, making "Chunky" grow bigger and causing her more frustration. In the piano store, Luann tells Marge about a hypnotherapist named Dr. Wendy Sage, who had a mastectomy and chose not to have breast reconstruction surgery.
Lisa and Marge visit Sage, who uses hypnotherapy on them, transferring them to Lisa's mind. They see the "Chunky" word which takes up the entire space of her mind. They then travel to Marge's mind, where they discover that Marge's mother had said a hurtful word to her as a child: "plain". The word has been in her head for years. Realizing each other's insecurities, Marge and Lisa profess their love to each other, thus making "chunky" and "plain" shrink.
From Wikipedia (CC BY-SA 4.0).