Researchers led by Florida State University's psychology professor Pamela K Keel studied 960 college women and found that spending more time on Facebook was associated with higher levels of disordered eating.
The study found women who placed greater importance on receiving comments and "likes" on their status updates, untagged photos of themselves, compared their own photos to friends' posted photos, reported the highest levels of disordered eating.
"Facebook provides a fun way to stay connected with friends, but it also presents women with a new medium through which they are confronted by a thin ideal that impacts their risk for eating disorders," Keel said.
While other studies have linked social media and eating disorders, the study is the first to show that spending just 20 minutes on Facebook actually contributes to the risk of eating disorders by reinforcing women's concerns about weight and shape and increasing anxiety.
The finding is significant because more than 95 percent of the women who participated in the study use Facebook, and those with Facebook accounts, described checking the site multiple times a day, typically spending 20 minutes during each visit.
That amounts to more than an hour on Facebook each day, according to Keel.
Researchers have long recognised the powerful impact of peer/social influences and traditional media on the risk for eating disorders. Facebook combines those factors.
"Now it's not the case that the only place you're seeing thin and idealised images of women in bathing suits is on magazine covers," Keel said.
"Now your friends are posting carefully curated photos of themselves on their Facebook page that you're being exposed to constantly. It represents a very unique merging of two things that we already knew could increase risk for eating disorders," Keel said.
The research is important because it may lead to interventions to reduce risk factors for eating disorders, which are among the most serious forms of mental illness.
"Eating disorders are associated with the highest rates of mortality of any psychiatric illness," Keel said.
Ironically, Facebook may be one of the best ways to employ intervention strategies, such as encouraging women to put a stop to so-called "fat talk," researchers said.The findings were published in the International Journal of Eating Disorders.