Woman, Eating follows Lydia, a twenty-three-year-old vampire of mixed Japanese and Malaysian heritage, as she navigates independence in London while grappling with her identity, hunger, and toxic relationship with her centuries-old mother.

The novel opens with Lydia meeting Ben, an artist who helps run a studio program in a converted chocolate factory. Lydia has been awarded a studio space in this largely windowless building, which appeals to her due to her extreme photosensitivity. During their initial meeting, Lydia lies about her mother being dead, a falsehood that immediately resonates with Ben, whose own mother is terminally ill. After signing the paperwork for her studio, Lydia reflects on her exhausting morning of moving her deteriorating mother into an assisted-living facility called Crimson Orchard.

Lydia's backstory reveals the complexity of her vampiric existence. Born human but turned into a vampire as an infant by her mother—allegedly to save her life—Lydia has lived with profound shame about her body and nature. Her mother, turned into a vampire by a white British colonizer in Malaysia, has passed down deep self-loathing, teaching Lydia that their bodies are 'disgusting and devilish.' Their diet consists exclusively of pig's blood, which her mother procures because she believes they are only worthy of consuming from 'dirty, lowly' animals.

Struggling to find blood in London, Lydia's first attempt to purchase pig's blood from a butcher fails when she awkwardly claims to need it for performance art. Her situation worsens when she discovers that her luggage, containing her human birth certificate and other prized possessions, has been lost at St. Pancras station. That night, she illegally sleeps in her studio, which is designated only for artistic work.

Lydia begins an internship at the OTA art gallery, colloquially known as "The Otter," where she hopes to learn about artistic practices but instead finds herself used as free labor. During her first day working a puppet show exhibition, she becomes fixated on a particular female puppet and impulsively steals it, taking it back to her studio.

As Lydia's hunger intensifies, she orders dried pig's blood online, but the package becomes inaccessible in a lockbox. When Ben appears with fresh cuts from a biking accident, Lydia's desperation overwhelms her control. Under the guise of helping clean his wounds, she licks blood from his neck, attempting to kiss him in the process. Ben awkwardly rejects her, mentioning his fiancée, and Lydia flees in mortification. Later, alone in her studio, she desperately sucks the remaining blood from the cleaning rag.

A visit to Crimson Orchard reveals her mother's continued deterioration. The staff reports that her mother has been violent, biting a nurse, and has been craving Malaysian sweets—surprising given her usual reluctance to discuss her pre-vampire life in Malaysia. During the visit, Lydia's mother appears confused, speaking in different voices and initially failing to recognize her daughter. Lydia brings blood sausages for her mother and reminds her to eat alone, triggering painful memories of her own childhood isolation during school lunches.

At the Otter, Lydia meets Gideon, the gallery director, who shocks her by revealing he owns paintings by her deceased father, Taiyo Kobayashi. This encounter leaves Lydia feeling displaced—a stranger possesses her father's artwork while she has never seen his paintings herself.

The situation at the Otter deteriorates when Gideon sexually harasses Lydia during an evening event, groping her and later sending an inappropriate email. Meanwhile, Lydia's artistic awakening begins when she discovers a dead duck and, driven by starvation, feeds on its blood. This act of independent hunting, rather than consuming her mother's chosen pig's blood, transforms her physically and psychologically. She feels empowered, with 'airy' bones inherited from the duck's blood, and experiences newfound confidence.

This transformation enables Lydia to join a communal dinner with other artists, where she meets Ben's fiancée Anju and receives a warning from Shakti, a former Otter employee, to be careful of Gideon. That night, filled with artistic fervor from her feeding, Lydia creates a striking new painting. She researches her stolen puppet, discovering it represents Baba Yaga, the Slavic folk figure, and begins calling it 'Yaga.'

During another exploitative event at the Otter, Ben invites Lydia to abandon her post and attend his friend's art exhibition. Walking home together, Ben confides about his relationship difficulties with Anju and his fears about his dying mother. He shares his art project inspired by Carl Linnaeus's Flower Clock, motivated by his mother's fluctuating cancer prognoses. The evening culminates in Ben and Lydia sleeping together.

The aftermath proves devastating. Ben discovers the duck carcass in Lydia's sink and leaves abruptly in disgust to see Anju. Lydia spends the weekend in a depressive spiral, lying on her studio floor watching Buffy the Vampire Slayer and obsessing over online videos of people eating—particularly Japanese cuisine that connects her to her father's heritage.

Desperate and inspired by Baba Yaga mythology, which mentions the witch drinking milk alongside blood, Lydia attempts to consume milk from the communal kitchen. The milk causes violent convulsions and turns her veins white as she slips into a near-death state. In a dream-like vision, she encounters her mother at Crimson Orchard and finally articulates her rejection of the shame-based worldview she was raised with, declaring that vampires are "not inherently evil" but 'simply just a different form of being.'

Maria and Ben find Lydia collapsed and unconscious. When she recovers, Ben reveals that he's staying with Anju and moving away to care for his mother. His final rejection forces Lydia to confront the impossibility of achieving the normal human life she has desperately sought.

Realizing she must stop 'acting human,' Lydia enters a starving haze in her studio, hallucinating conversations with the Yaga puppet that urge her to embrace her hunger. She wanders London observing people eating and living normal lives before encountering Gideon at the Otter. When he touches her inappropriately again, Lydia bites his neck, killing him while absorbing his memories and experiencing his lifetime of sexual assaults.

Through consuming human blood—Gideon's and another victim's—Lydia finally tastes the global cuisines she has longed for, as the blood carries their food memories. Empowered by human blood consumed in truly filling quantities for the first time, she gains unprecedented confidence and strength. Taking only the Baba Yaga puppet as her companion, Lydia leaves the studios forever, briefly encountering Ben to tell him she must go before disappearing into the night—having fully embraced her predatory nature while abandoning any pretense of human integration.