Much has been made over the years about how mainstream media presents unrealistic beauty standards in the form of photoshopped celebrities or stick-thin fashion models.
Using social media does appear to be correlated with body image concerns. A systematic review of 20 papers published in 2016 found that photo-based activities, like scrolling through Instagram or posting pictures of yourself, were a particular problem when it came to negative thoughts about your body.
In a survey of 227 female university students, women reported that they tend to compare their own appearance negatively with their peer group and with celebrities, but not with family members, while browsing Facebook. The comparison group that had the strongest link to body image concerns was distant peers, or acquaintances.
People generally present a one-sided version of their life online. If you know someone well, you’ll know they’re only showing the best bits – but if they’re an acquaintance, you won’t have any other information to go on.