Beauty is in the eye of the beholder, and it seems all the fitness influencers on Instagram have triggered a cultural shift.

The University of Missouri-Kansas City asked 78 female undergraduate students to rate the winners of the Miss USA beauty pageant, and the researchers discovered that women with toned or muscular figures are now seen as sexier as women who are very thin.

The students were asked to study photos of the women who were crowned Miss USA between 1999 and 2013 and rate them according to how muscular, thin and attractive they were.

The study found more of the recent winners were muscular and toned rather than thin, which showed that attitudes toward physical beauty have shifted.

Head researcher Frances Bozsik published the study’s findings in the journal Sex Roles, explaining: “There is a shift in the thin ideal female figure to one that now includes the appearance of physical fitness via muscularity.”

She added that this was connected to the explosion of “fitspo” on social media channels.

Frances also noted that both muscularity and thinness were commonly found among female celebrities.

Referring to sites such as Instagram, Tumblr and Pinterest, she explained how being able to curate collections of fit and healthy idols can also encourage eating disorders.

She said: “These websites allow individuals to collect images of women with whom they identify or admire, essentially allowing them to cultivate their own media repertoire of highly salient thin and fit media.

‘This process of selecting preferred images and then narrowing the media focus by placing these images on their ‘boards’ may inadvertently increase the risk of developing higher levels of body dissatisfaction, as well as subsequent disordered-eating behaviors that are linked to it.”

A second study carried out by the university saw 64 students presented with pictures of 14 different women.

Each shot was paired up to show the woman with and without muscle definition — a combination that saw the pictures both deemed equally attractive.

But when one of the photos was left untouched, the results showed that the subjects found the more muscular version more attractive.