Big is Beautiful follows the journey of a diverse group of overweight women who come together in a therapy group at the famed Savoy hotel. As they navigate their weight disorder and face societal pressures, they find support, empowerment, and friendship.

Isabelle and her niece Nina open a "fasting and detox" cure in the heart of Provence, with the help of Baptiste, a yogi and handyman, Jessica, a tantric masseuse, and Maxime, a seductive equine therapist. Among the first curists, four overweight teenagers sent by the town hall; Marion and Lio, her skinny sister who imposes the cure on her "for her own good"; and their friend Émilie who, having shed her extra kilos, discovers as soon as she arrives that her beloved husband is swooning in the arms of a man... who is clearly overweight!