“You won’t think your way out of this, your therapist says,” Sarah Moss writes toward the end of her powerfully original and unsettling memoir about anorexia. “You have to act, and it will be difficult and uncomfortable and you will have to do it consistently.”

By this point in a story that stretches from the English novelist’s fraught childhood to her successes as author and professor, the reader is so relieved to hear a sympathetic voice addressing Moss that the therapist’s simple, if painfully difficult, directive has a poignant resonance.

Moss has indeed spent much of this inventive narrative trying to think her way through her illness, tracking its origins, personal and cultural, and has taken us down many brilliant pathways. But for her sake we hope, finally, that she will also act.

Some who write about anorexia’s fierce compulsions address the disease as an addiction. For Moss, it is an endless argument, one that began — as it often does for girls — in adolescence, then roared back with near-lethal vengeance in her mid-40s. From early days, Moss has heard critical voices calling her greedy and troublesome, and she captures their harshness not just in passages about her eating, but also as an irritable chorus questioning her memoir’s very project.

The first of the book’s three sections covers Moss’s upbringing in the north of England with two self-involved, withholding parents — her father an American academic prone to occasional rages, her mother a feminist fighting her own demons and passing along weight anxiety to her daughter.

The narrator’s memories of a household where “care and attention are scarce resources, not to be wasted on the undeserving,” are challenged by her italicized critic: “Other people, eyewitnesses, would tell it quite differently, this story, you have no right, no right at all, you always make stuff up, you can’t resist—”

The interruptions give the telling a staccato rhythm, but also convey the precarity of the writer’s trust in her own experience.

Moss’s use of the second person through much of the book enhances this sense of distance; she switches to the third person in the central, most harrowing section, an account of her recent stay at a squalid, underfunded hospital when she was on the verge of organ failure. (“She had used to sweat at moments of tension, but her body had turned off that function months ago.”)

She employs fable-like names for family members — her father is “the Owl,” her mother “Jumbly Girl,” her rarely mentioned brother the “Angel Child” — as if this were more a sinister fairy tale than a memoir, and invokes the title’s imaginary wolf as her protector, and a companion on journeys back to a younger self. “Wolf, tell that little girl: Those are just feelings. You can manage them.” “Wolf, walk beside that fading girl.”

If Moss is forever suspicious of her body and its appetites, she is always content to feed her energetic mind by reading. She weaves literary analyses into her complex, textured story. (One of the few activities she did share with her mother, incidentally, is sewing and dressmaking.)

She revisits favorite authors from childhood, Laura Ingalls Wilder and Arthur Ransome, hunting for images of food and nurturing, and brings a feminist and anticolonialist sensibility to the stories of women and their madnesses found in the work of the Brontës, Plath and Woolf. She wanders imaginatively along the peaks of the Lake District with Dorothy Wordsworth.

Sarah Moss’s eight novels include the short, suspenseful “Ghost Wall” and “The Fell,” a book I press on anyone who asks whether great fiction has been written about the pandemic. Fans of Moss’s work will recognize in “My Good Bright Wolf” the ominous air of danger, the alertness to class issues and the figure of a bright, spiky woman chafing against restrictions. They will discover the source of the author’s passion for climbing mountains and the freedom she feels being outside in the natural world, which have found expression in her novels.

The last section, “A body of one’s own: thinking,” contains this story’s lightest and darkest moments. Moss has the courage to capture, lyrically, the self-annihilating impulse at the heart of her predicament — “if you were going to fall, this would be a good place” — an anguish recognizable to many readers, not only those who suffer from anorexia. Saving her is the thought of her sons.

Earlier, in a description of a family hiking trip in Italy, Moss finally allows her husband and grown-up sons to appear, and reveals herself as a caring, diligent mother. It is clear that Moss’s family knows about her struggles, when she has an anxious flare-up after an encounter with an angry stranger.

In a loving gesture, “your older son puts his hot hand on your sweaty shoulder.” He knows he cannot drive out his mother’s self-critical voices, but we feel the touch itself as a comfort.