Internal studies from Facebook conducted over the last three years reveal that the company is aware Instagram can have a harmful impact on teenagers’ mental health, the Wall Street Journal reported on Tuesday. This comes several months after the social media giant announced it was creating a separate Instagram for children younger than 13.

Facebook CEO Mark Zuckerberg previously publicly played down the negative side effects of its platforms, notably Instagram. In testimony before Congress in March, Zuckerberg pointed to the positive mental health benefits of social media use when asked about whether it could adversely affect children’s mental health.

The internal study findings have not been released publicly, but the WSJ found that Instagram can exasperate the feelings of depression felt in teenagers and that this was especially acute with girls.

“Thirty-two percent of teen girls said that when they felt bad about their bodies, Instagram made them feel worse,” the Facebook researchers reportedly wrote in the study. Teen boys also experienced the same negative feelings, but the number reporting this feeling in the study was 14%.

Another troublesome finding was the impact Instagram had on young people experiencing suicidal thoughts. In the study, one Facebook presentation showed that 13% of British users and 6% of Americans traced the issue to Instagram.

Instagram chose to address the Journal's reporting in a blog post on Tuesday where it rebuked its story, saying that it focused on a "limited set of findings and casts them in a negative light." It went on to say it stood by its research findings which "demonstrates our commitment to understanding complex and difficult issues young people may struggle with."

The post also shared some of the company's thinking on ways to address some of the problems identified in its research and the company's report. One idea is to "nudge" users away from certain forms of negative content that they appear fixated on and toward different material. Instagram said it is "cautiously optimistic" about the proposal.

What the studies make clear is how the fundamental challenges Facebook encounters in reducing these negative effects cuts to the core of their business model. The aspects of Instagram that most affect young people’s mental health, like the Explore function that curates material from accounts based on previous interactions with the site, are designed to encourage more use. Some teens admitted to the WSJ that they felt “addicted” to Instagram which kept them from cutting down on use.

While the majority of Instagram users use the app without reporting negative problems for their mental well-being, Facebook researchers noted that the app’s core functions inadvertently played on each other to create a “perfect storm” of these problems.

These findings were shared with Facebook executives, including Zuckerberg, as part of a presentation last year. It demonstrated that at the very least Facebook officials are aware of the downsides of their services despite publicly playing down the risks.

In March, Facebook announced that it was developing a version of Instagram for those 13 years of age and younger. The launch date is not yet known.