The Women’s Equality Party (WEP) has launched a campaign to demand greater body diversity in fashion and is looking to enlist the help of London Mayor Sadiq Khan and chair of the Women and Equalities Commission Maria Miller to hold the industry to account.

Its campaign includes demands for models with a BMI of less than 18.5 to be seen by a medical professional from an accredited list to assess their health, a demand that designers at London Fashion Week create two sample sizes of which one must be at least a size 12 and commitments from fashion magazines to include at least one feature on plus size models per issue.

The party will also launch an interactive social media campaign #NoSizeFitsAll to co-incide with London Fashion Week from 16-20 September, which invites women to share images of themselves on social media and Tweet or email the British Fashion Council to apply pressure on the organisation, which owns London Fashion Week, to cede to its demands.

According to The Observer, the WEP plans to ask London Mayor Sadiq Khan to withdraw support from London Fashion Week if its demands are not met and will call upon Maria Miller to hold a public hearing in which designers will be asked why their clothes are based on “an unattainable level of thinness in women”.

In a statement on its website the party sets out its agenda for launching the campaign. “The presentation and idolisation of a uniform body type by the fashion industry has significant and wide-reaching consequences,” it says. “28 published empirical studies from the UK, Europe, North America and Australia have found that media images have a direct impact on how negatively or positively we view our bodies, with negative body image putting someone at a considerably heightened risk of developing an eating disorder.”

“Eating disorders affect 1.6m people in the UK, 89% of whom are female. 14-25 year olds are the demographic most affected by an eating disorder, with 5% of girls and women suffering from anorexia — the most deadly psychiatric disease (10-20% of cases are fatal),” the statement says.

The British Fashion Council already has guidelines in place around model health and well-being. In 2007 it commissioned the Model Health Inquiry and significant updates were made to it following a review of the findings last year.

A Model Zone has been set up for London Fashion Week where models can relax between shows and eat healthy food and a therapist is on hand to whom models can turn to discuss issues that may be troubling them – if models cannot attend in person they are provided with a number they can text for advice.

Models are also provided with contact numbers for union Equity, should they wish to enlist independent representation (the union opened up its membership to models following 2007 inquiry), and for eating disorder charity BEAT. A previous voluntary pilot scheme, which assessed models on BMI, was not pursued as it was argued that BMI is not an accurate measure of model health and some models felt the process was intrusive and they were unfairly singled out.

The Industry has approached the British Fashion Council for comment.