According to the UK's Advertising Standards Authority (ASA), the European division of Philadelphia-based company Urban Outfitters was guilty of "irresponsible and harmful" advertising for using an image of an "unhealthily thin" model.

Following an anonymous complaint, the ASA reviewed the advertisement in question found on the retailer's website. The division of URBN INC was subsequently ordered to remove an ad for a pair of "polka dot mesh briefs" on the basis that the photo, which shows a model with a significant gap between her thighs, fueled unhealthy body image.

So-called "thigh gaps" are a trend that has been popular among teen girls and rose to media prominence last year. The trend involves the idea that girls don't want their thighs to touch, but rather seek to attain a space in between their legs.

"We understood that Urban Outfitters' target market was young people and considered that using a noticeably underweight model was likely to impress upon that audience that the image was representative of the people who might wear Urban Outfitters' clothing, and as being something to aspire to," the ASA said in the adjudication. "We therefore concluded that the ad was irresponsible."

Since the decision, which requested Urban Outfitters remove the image immediately, Urban has changed the image to this:

The company, however, asserted that the model was not unhealthily thin and that it is "common practice to use slim models in the underwear industry." Various similar images of models with prominent thigh gaps still exist on the site.

While there are no suggestions from the ASA or Urban Outfitters that the original ad image was altered, stores commonly use Photoshop to slim down models. Urban Outfitters is no stranger to excessive Photoshopping—in Oct. 2014, the retailer removed a model's entire leg from an email blast ad.