The Edible Woman revolves around Marian McAlpin, a young woman who experiences a crisis of identity after her boyfriend, Peter, proposes to her. Set in an unnamed city in Canada, the novel focuses on themes of gender, expectations of women, masculinity and femininity, and female agency. It uses food, and Marian's growing inability to consume various foods after her engagement to Peter due to imagined metaphorical cannibalism, to explore female experiences in society.
Marian McAlpin lives in an apartment that she shares with one roommate, Ainsley, in an unnamed city in Canada. The two women rent the apartment from the "lady down below," who is highly critical of the two women's lifestyle—although most of the behavior that she disapproves of, like their drinking, is actually attributable to Ainsley, not Marian—partially due to her fear of their "improper" behavior influencing her daughter. Ainsley is a loud, outspoken feminist who drinks liberally and leads an active sex life that she flaunts and talks often about to Marian and her coworkers. Although Marian and Ainsley spend a lot of time together, Marian doesn't feel particularly close to Ainsley.
Marian works at Seymour Surveys, a market research company that employs mainly women. She feels like her job is a dead end, unsure of how she could be promoted, since it appears that there is no better position available at the company. She is stuck, and finds herself executing tasks that have little to do with what her actual role requires, even though she is college-educated and fully qualified to take on more responsibility within the company. The women at Seymour Surveys are representative of conventional women who adhere to stereotypical female roles. They are conservative and all hope to get married, causing Marian to refer to them as the "office virgins." At the beginning of the novel, Marian is assigned to conduct a door-to-door survey by her boss, Mrs. Bogue, asking men about their beer consumption.
Marian goes to visit her friend, Clara, who is pregnant with her third child. Clara is another representation of someone who conforms to oppressive expectations of women. She is a housewife, spending her days taking care of her children while her husband, Joe, works at the local university. Ainsley joins Clara and Marian and Marian, Clara, Joe, and Ainsley have awkward conversations and when Marian and Ainsley leave, Ainsley critiques Clara and Joe's marriage, stating that Clara is constricting Joe by being helpless and needy.
While Marian conducts the surveys, she meets Duncan, a graduate student in English that invites her into his apartment. She accepts, even though she is deeply uncomfortable. Duncan is very thin and strange, crafting elaborate lies to mislead Marian just for fun and talking with her at length. He displays a deep insight into Marian's emotions, and states out loud what she is thinking, surprising her and further causing her more discomfort. Even though she is perturbed by Duncan, she is intrigued and leaves his apartment in a state of confusion about her feelings towards him.
Over the course of the novel, Marian interacts with her friends and feels distant from them. She is often silent when with them and feels alienated by their excessive drinking or her own inability to maintain sobriety. She constantly attempts to leave or experiences deep feelings of discomfort. She doesn't approve of many of her friend's decisions, but never states her opinions out loud, leading to Marian's growing feeling of being suffocated and constricted. Much of her disapproval is centered around Ainsley, who decides to get pregnant and raise a child alone in order to ensure a strong mother-child relationship and due to her belief that fathers corrupt children.
Marian goes to her boyfriend Peter's apartment. Peter is a stereotypical man; he is attractive, a rising lawyer, and treats Marian with little real empathy or understanding. At first, their relationship is defined by the understanding that neither is serious about the other. However, shortly after this visit, Peter proposes to Marian, explaining that it will make him more presentable at his law firm and that she is extremely sensible. Even though Marian is engaged to Peter, when she runs into Duncan at a laundromat by chance, they have another conversation that makes Marian both intrigued and uncomfortable and they kiss.
After Part I ends, Part II begins with a switch in narrative voice, going from first-person to third-person. Marian and Peter continue to see each other. Marian routinely states that she doesn't really know or understand Peter. Simultaneously, Duncan and Marian also continue to see each other in secret. After witnessing Peter eat a steak at dinner, Marian begins to feel extreme disgust towards meat, imagining in vivid detail the act of killing and dismemberment that occurred when the cow was killed for consumption. This moment starts the "metaphorical cannibalism" that plagues Marian and represents her continuing feeling of being suffocated by her relationship with Peter. She imagines life in the food she eats and feels like she is killing these lives, just like Peter is slowly silencing her and killing the freedom that she has.
Ainsley succeeds in having sex with Len and becomes pregnant. This leads to extreme conflict between Len and Ainsley, since Len feels like Ainsley used him. Clara has her third child and Marian goes to visit her. She tries to tell Clara about her problems eating, but Clara dismisses them, as does Duncan when she tells him about her issues.
Peter hosts a party, for which Marian gets dressed up in an outfit that departs from her usual style. She gets her makeup and hair done and wears a seductive red dress. Peter loves how she looks, a moment of irony since the get-up makes Marian feel completely unlike herself to the point where she doesn't recognize herself. She invites Duncan to the party. When he arrives, he cruelly laughs at Marian's appearance and leaves the party. At the party, Ainsley meets Duncan's roommate, Fish, and the two end up marrying each other shortly afterward, with Ainsley satisfied that she has found a father for her child—something she realized she wanted after she was already pregnant, going back on her initial vow to raise the child without a father. After the party, a few days later, Marian and Duncan go to a museum and agree to have sex. They go to a sleazy hotel. The experience is awkward and unsatisfying and the next morning, Marian is unable to eat anything.
Marian realizes that Peter has been suffocating her and trying to "assimilate" her. She bakes a cake in the shape of a woman and presents it to him as a substitute. However, unexpectedly, Peter doesn't eat it and the two break up. Part III, the final chapter, follows the breakup and returns to a first-person point of view. Duncan and Marian see each other again and Marian offers him the cake she baked for Peter. Unlike Peter, Duncan eats the cake, stating that it was "delicious."