To call Samantha Irby’s book scatological would be an understatement. This is a book about assholes – yes, the kind who cheats on you, or never calls, or is “a grown man with a college degree who told me that he only ate angel-hair pasta” – but most of all it is a book about Irby’s bowels and how they ruin her life. Meaty is – like Irby’s blog, bitchesgottaeat – an episodic collection of diaries, memories and views on life with no narrative beginning, middle or end. It’s in the tradition of Helen Fielding and Candace Bushnell, certainly, but this rackety life of dating, renting and running out of money is heavily overshadowed by Irby’s Crohn’s disease, and is set in the social media age. Irby will tell you how to cook an inflammatory bowel disease-friendly frittata, while hungover, for a date who has woken up in your apartment, and how to Instagram it, too. Or inform the reader that Martha Stewart “calls for fresh squeezed” orange juice “but, like, LOLWAT”.

The tone, like that of many successful bloggers and YouTubers, is immediate, seemingly unedited and wilfully oversharing: “I suck my thumb when I masturbate,” she writes, defiantly. It’s also very sweary. Many chapters open with a blunt statement, some more profound than others: “When I was 19 I lived in a fucking crack house”; “I was still a kid when I first figured out that I am ugly.” She skims over the story of her alcoholic father, and of being homeless twice, but writes a heartbreaking chapter about being a carer for her mother, who had multiple sclerosis and dementia and left Irby an orphan in her teens.

Referring to her beloved parent as “my baby” and “my daughter”, Irby describes trying to kill herself when she was 13, adding sadly that “you don’t just get to withdraw from your child life while making sure that your disabled mother doesn’t set the apartment on fire because her fingers can no longer close firmly around a cigarette.” It’s no wonder she swears.

Meaty makes for difficult reading. I winced every time Irby referred to her body as “meat” or a “meat carcass”. But she is unapologetic about it, and rightly so. At one point, after sharing the entire pilot episode for her imaginary TV show, she says: “I want to put a fat bitch on network television.” The TV rights to the book have of course been sold. And anyone who tries to introduce assholes to the Instagram generation should be saluted.

• Meaty is published by Faber (RRP £9.99). To order a copy go to guardianbookshop.com. Free UK p&p over £15.