Amid the photographs and frocks on display in the Imperial War Museum's exhibition Fashion on the Ration (in London last year, now in Manchester) was an unsettling panel equating the wearing of make-up with national morale. Women in the 1940s, it suggested, were encouraged, obliged even, to look their best at all times, regardless of shortages, fatigue, anxiety or bombs; to keep their hair neat, their lipstick bright, and present a trim figure that told the men fighting: we believe you're winning.

The two elderly women whose voices are heard in Mighty Heart Theatre's When I Feel Like Crap I Google Kim Kardashian Fat speak of the past with a glow, as a time when women felt less media and social pressure to conform to a particular look or body image. Whatever they did have to contend with, they didn't have Photoshop or Instagram, or an unregulated diet industry revelling in its ability to profit from human insecurity. But the more depressing impression to emerge from When I Feel Like Crap..., a verbatim show constructed from interviews and online surveys with “self-identifying women” of all ages (and, it's implied, backgrounds), isn't the known problem that personal appearance is a political issue, but the unknown extent to which that policing has been internalised, as one voice after another confesses to judging others as severely as herself.

More upsetting still is the extent to which these women have risked, and experienced, physical harm as a result of their obsession with body image. One woman describes her most successful diet as smoking rather than eating; two others gave birth to premature babies because they willingly malnourished themselves while pregnant; one was hospitalised with excess acid after eating only oranges and another destroyed her metabolism and ultimately developed cancer of the rectum from a lifetime of extreme dieting. When a woman listing off her approaches to weight loss says “anorexia is the only thing I've never done”, the pressing need for better education about physical and mental health couldn't be more clear.

The material is cumulatively devastating, yet Mighty Heart – researcher-performers Lisa-Marie Hoctor and Sam Edwards – leaven it with defiant humour and a buoyancy reminiscent of the Eggs Collective. Dressed in skin-tight leopard print that embraces every one of their lumps and bumps, they sing one interview in the style of a Disney princess (their gift to the woman told that she was too heavy, by a mere 2kg, to play the role of Tinkerbell in Disneyland) and transform a “Scouse beauty routine” into a cheeky game show. And there are just enough stories of women rejecting the entire premise of body image policing, whether by wearing “loads of make-up because it's always in my size” or recovering from bulimia and beginning to find genuine pleasure in the way they look, to make the note of hope at the end of the show chime real.

That hope is dependent on all bodies and shapes being accepted. It's no good celebrating the natural curves of “real women” (cf the Dove campaign) if it leaves naturally thin women feeling condemned as less than real. This is where the note of inclusion struck by the phrase “self-identifying women” is so vital. “No one aspires to be normal,” says one woman, but perhaps they might if the notion of normal were expanded beyond its narrow limit to encompass the full spectrum of humanity. (MC)

When I Feel Like Crap I Google Kim Kardashian Fat is on at 16.40 at Silk Nightclub as part of PBH Free Fringe until August 27th (not Tuesdays). See venue for accessibility information - http://freefringe.org.uk/edinburgh-fringe-festival/when-i-feel-like-crap-i-google-kim-kardashian-fat/2016-08-17/

On the diet industry: https://www.theguardian.com/lifeandstyle/2013/aug/07/fat-profits-food-industry-obesity

On sugar addiction: https://www.theguardian.com/lifeandstyle/2013/aug/07/fat-profits-food-industry-obesity

On physical and psychological effects of dieting: http://eating-disorders.org.uk/information/the-psychology-of-dieting/

On anorexia and mental health: https://www.mentalhealth.org.uk/a-to-z/e/eating-disorders

On the language that surrounds gender non-conformity: http://morganpotts.com/2016/gender-discourse-an-open-letter-to-sisters-uncut/

The Eggs Collective: http://www.eggscollective.com/

Mighty Heart's site: http://mightyhearttheatre.wixsite.com/mightyhearttheatre

If you're in or near Manchester, the Fashion on the Ration exhibition is wonderful: http://www.iwm.org.uk/exhibitions/iwm-north/fashion-on-the-ration-1940s-street-style