The gnawing omnipresence of an eating disorder becomes the source of body horror in Samantha Aldana’s accomplished, visually impressive debut. Drawing from her own experience of bulimia, co-writer Kelly Murtagh is phenomenal as Ivy, an aspiring jazz singer who is trapped in an endless cycle of bingeing and purging. Straightforward in terms of plotting, the harrowing character study opts to render the frightening effects of Ivy’s psychological condition through a distinctly sensorial soundscape.

Sensitive to the presence and mentions of food, Ivy seems to exist outside her own body. Her mind is occupied with the sounds of sweet wrappers being torn open, cereal clattering against a glass bowl, the beeping tones of the register as a cashier marvels at her unusually large grocery order. The camera also stalks Ivy physically, echoing the character’s destructive obsession with her body; she can’t help but stare at every reflective surface.

Deep in the fugue of her turmoil, Ivy begins to hallucinate strange growths and deformities on her flesh; these genre elements are however only one small aspect of what makes Shapeless so effective as a horror film. Ivy’s bulimia is not merely a shock device but a constantly self-destructive ritual that has eclipsed the entirety of her existence, threatening to destroy her interpersonal relationships and even her voice. For these personal demons, there is no cut-and-dried exorcism, and the film also refuses to wrap itself up with an easy catharsis. Like the surreal, haunting image of a smiling Ivy lying atop a heap of food wrappers, tinfoil and garbage bags that lock her in an eerie embrace, what Shapeless leaves us with is the all-consuming loneliness that living with an eating disorder brings.

• Shapeless is released on 19 September on digital platforms.