thoughts, 13% of british users and 6% of american users traced those thoughts to instagram use. though facebook insists far more teens benefit from the social connections. more of them found their engagement on instagram helpful than harmful. reporter: but 20-year-old grace park believes the constant instagram posts contributed to her own anxiety and eating disorder in high school. everyone else is way skinnier and way prettier and had nicer clothes, and that also sort of hurt my own self-confidence about my own body, which led to me practically starving myself for like a year. makes them feel like they re on shaky ground and that they can t possibly keep up with their peers or anyone else. and it just makes their insecurity snowball at a time when they re very vulnerable. reporter: facebook has paused a plan to roll out instagram to even younger kids, 8 to 12. as congress considers legislation to limit their ability to target kids.