Models used in social media postings, or more than a decade's worth of Miss USA beauty pageant winners tell us that thin female bodies are still rated as attractive. However, US women's perceptions of what constitutes the perfect female figure have evolved in recent years to a "thin and toned" ideal. This is according to Frances Bozsik of the University of Missouri-Kansas City in the US, who led a study in Springer's journal Sex Roles.

Bozsik and her team turned to the Miss USA competition, where pageant winners are chosen annually. Competitors are primarily judged based upon their appearance and, in part, based upon how well they fit current beauty standards. Photographs of the 1999 to 2013 winners wearing two-piece swimsuits were shown to 78 undergraduate women. Participants then had to rate the crowned beauties according to how muscular, thin and attractive they were. Based on these ratings, Bozsik's team established that recent winners no longer only exemplify the body ideal of thinness, but have also become increasingly muscular over the past 15 years.

In a second study, the researchers investigated whether the long-held ideal female figure of extreme thinness is also changing to include enhanced muscle tone. Pairs of photographs depicting 14 women were shown to 64 undergraduate students. Each of the pairs was identical in all aspects, except that in one version the muscular definition of the woman's body was digitally removed. This resulted in one "thin only" image, and another "toned and thin" picture. When the images were shown to study participants separately, they rated the "thin only" and "toned and thin" versions as being equally attractive. When the images were presented side-by-side in pairs, the participants rated the thin, muscular figures to be the more attractive ones.

"There is a shift in the thin ideal female figure to one that now includes the appearance of physical fitness via muscularity," says Bozsik, who explains that the results of the current study further suggest that muscularity and thinness are becoming more ubiquitous among female media figures.

She notes that the increased preference for a toned and thin female figure over a solely thin one is consistent with the models commonly seen in so-called "fitspiration" media posted on social media.

"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," says Bozsik.