Sarah Moss’s memoir, the story of how her upbringing developed in her a lifelong, destructive relationship to food, is full of daring. It is a complicated tale and her telling is many-sided, as full of devastation as it is wisdom.

The author, an academic, is best known for her novels (most recently The Fell), in which she variously dissects the climate emergency and Britishness after Brexit. Here she continues to write with wit about humans’ relationship to the natural world. Unlike Moss, who was raised to climb mountains, her husband “had never experienced the need to scramble at the top of a stony or muddy summit for ideologically questionable reasons regrettably related to colonialism, imperialism and the need to look down on everything”, she teases.

Moss was born in Glasgow in 1975 and grew up in Manchester. She gives her family members unexplained nicknames: her grandmother is “the Wicked Witch of the West” (though Moss never met her); her father “the Owl”. Her mother is “the Jumbly Girl”, her brother “the Angel Boy”.

A tension is evident from the first few pages. After a section of Moss’s second-person narrative (she addresses herself as “you” for the bulk of the book), another, italicised voice appears, contradicting her, telling her to “shut up, no one cares”, accusing her of lying. This is the niggling voice in the back of your head, the one that makes you doubt what you know to be true. Its presence is felt throughout.

Moss’s childhood is dominated by the fear of putting on weight. “You’ll get fat like your mother if you eat those biscuits,” the Owl tells her. It’s not just her parents. Moss “never encountered one woman who was not on a diet”. She follows suit and finds dieting easy. “You decided not to eat and you didn’t eat. You went hungry. The next time you were weighed, the number was even better,” she writes, so straightforward about this most destructive of patterns.

The voice in the back of her head continues to second-guess Moss’s narrative. It’s there when she recalls the school nurse asking how she got that bruise, and her mother laughs, saying: “She’s going to tell you… that her father kicked her, but of course it’s not true”. It’s there when she remembers when, on a sailing holiday with her parents, a combination of meal-skipping and a long period in the cold results in her fingers turning black. The doctor says he usually only sees frostbite in rough sleepers. Concerned about her weight, he diagnoses her with anorexia. “But we’re about to spend a month hiking in the Picos de Europa,” the Jumbly Girl says. “We can’t be taking her to a psychiatrist.”

In the worst of these moments, Moss summons her wolf. “Whistle up the wolf,” she writes, imagining a “reverse ghost… a present voice to haunt the past” and comfort her younger self: “Wolf, tell that little girl: those are just feelings. You can manage them.” This creature, an affront to the voice in the back of her head but rarely in direct combat, is the star of this book. That the wolf exists means Moss does too.

She finds solace in books – Swallows and Amazons, Little Women, Jane Eyre. Aged 17, she reads The Beauty Myth by Naomi Wolf, which transforms her politics. “Your eating disorder made you a slave of patriarchy”, she comes to understand. Decades later she is still working out how her anorexia coexists with her feminism: “You don’t think you find other people’s fatness repellent… but you certainly act as if you do.” She sees that her eating disorder has made her a “hypocrite”, but knows that anorexia is not a logical disease.

The book’s central section is set in 2020, when Moss’s illness leads her to hospital, where she is at risk of heart failure and threatened with force-feeding. It is the only part in the third person, and neither the niggling voice nor the wolf appear here. Moss’s own mental turmoil (“an urgent question for the psychiatric patient is whether the voices of coercion and judgment in her head are better or worse than the voices of coercion and judgement in the medical system”) is troubling enough.

A lesser writer would overdo these refrains. But Moss wears them lightly, subtly using the doubting voice and the heroic wolf to tangle preconceptions of reality as she forges her own way of writing memoir. In doing so she brings to mind the work of the Nobel prize-winning French author Annie Ernaux, who interrogates her memory as she commits her life’s story to the page.

For Moss, the result is a book so full of workings that its bleak subject matter is turned warm – and revelatory.

• My Good Bright Wolf: A Memoir by Sarah Moss is published by Picador (£18.99). To support the Guardian and Observer order your copy from guardianbookshop.com. Delivery charges may apply.