A third of girls will not post selfies online without using a filter or app to change their looks, while the same amount have deleted photos with too few "likes", research has found.
Around half of girls and young women alter photos to enhance their looks online and "find acceptance", Girlguiding's annual Girls' Attitudes survey found.
34pc of 11 to 21-year-olds said they would not post a photo of themselves online without using a filter to enhance it first. And 33pc said they have deleted pictures that didn't get enough 'likes'.
The charity surveyed 2,186 UK females aged between seven and 21 for its annual report, to be released in full in September.
It said the increased time spent online during lockdown, coupled with exposure to "unrealistic" images of girls and women, is making pressures they face worse.
Almost four in 10 of the 1,473 respondents aged 11-21 said they feel upset they can't look the same in real life as they do online, with 44pc saying fear others will criticise them stops them from having their picture taken.
Girlguiding advocate Phoebe Kent said she feels influencer culture is one of the most damaging phenomena to emerge on social media.
As a young school girl, Ms Kent would think "how can everyone look so good online?" when filtered photos of her peers appeared on social media.
The 20-year-old, who is studying French and economics at the University of Warwick, said: "I think now because I'm older I'm able to critique the things I see online, and overcome it, but for younger girls and young women it just absolutely knocks your self-esteem.
"I know so many people that have just ended up coming off social media because they can't deal with the detrimental impact on their confidence and wellbeing. It's definitely impacting on mental health for so many girls and young women."