Social-media networks are meant to link you with long-lost school friends, college roommates, and Army buddies. But instead of establishing connections through the feeds, the networks are instead linked to increased social isolation, according to new studies released this week.

The social-media networks show unrealistic depictions of their peers’ vacations, perfectly-posed selfies, and delicious meals, which in turn can foster feelings of envy and alienation, according to two papers.

“We are inherently social creatures, but modern life tends to compartmentalize us instead of bringing us together,” said Brian Primack, director of the University of Pittsburgh’s Center for Research on Media, Technology and Health. “While it may seem that social media presents opportunities to fill that social void, I think this study suggests that it may not be the solution people were hoping for.”

Primack is the lead author on one of the papers, published this week in The American Journal of Preventive Medicine.

The Pitt team assessed nearly 1,800 young adults, ages 19 to 32, in late 2014. The group was asked about its use of 11 social media networks: Facebook, Twitter, Google +, YouTube, LinkedIn, Instagram, Pinterest, Tumblr, Vine, Snapchat, and Reddit. The respondents to the questionnaire were asked to report their frequency of use of the networks, and also their total amount of time on them.

The young adults’ perceived social isolation was then measured using the Patient-Reported Outcomes Measurement Information System.

The patients surveyed who were the most frequent users of the network – at least two hours each day – also had twice the odds for perceived social isolation, they find. Those who checked into the networks 58 or more times in a single week had three times the likelihood of isolation than those who checked in just nine times in the same period.

Another study in the latest issue of the journal Cyberpsychology, Behavior and Social Networking focused in on Facebook use among undergraduates in college.

The study group included more than 1,100 students, report the scientists from the University of Michigan in Ann Arbor, and the University of California – Santa Barbara. The students were all asked to report their total Facebook usage, including active minutes and passive use in monitoring their posts and the responses to them. The study group was also asked about self-objectification, well-being, and how they compared themselves to their online friends.

The authors report Facebook offers an idealized landscape – vacation pictures, delicious meals, and perfectly-posed selfies – which made some users’ quotidian lives pale in comparison.

“For women and men, Facebook use was associated with greater social comparison and greater self-objectifications, which, in turn, was each related to lower self-esteem, poorer mental health, and greater body shame,” they conclude.

Displacement of direct social experience, feelings of exclusion, and the pangs of envy for others’ perceived better lives could be behind the social isolation, the Pitt scientists hypothesized.

But the cause-effect relationship between social networks and social isolation is not yet clear, the Pitt team added. But they said it’s clear the link is not healthy.

“It’s possible that young adults who initially felt socially isolated turned to social media. Or it could be that their increase use of social media somehow led to feeling isolated from the real world,” said Elizabeth Miller, a Pitt pediatrician and another of the authors. “It also could be a combination of both. But even if the social isolation came first, it did not seem to be alleviated by spending time online, even in purportedly social situations.”

Facebook reports that it has amassed more than 1.86 billion monthly users as of the end of 2016.