A teenage reader of Seventeen magazine is hoping to change the title's practice of airbrushing images to make young girls appear flawless and thin.

Eighth-grader Julia Bluhm, 14, from Maine, delivered a 15,000-name petition to the Hearst magazine's editor-in-chief, Ann Shoket, on Wednesday calling for the magazine to publish at least one unaltered photo spread a month.

"A lot of my friends are happy in their skin, but I know people who aren't comfortable and wished they looked differently," said Bluhm, who dreams of becoming a professional ballet dancer and activist. "There are pictures all over the media that show photoshopped girls that have no flaws and they are perfect."

In her petition, titled Give Girls Images of Real Girls, Bluhm, a blogger with Sparksummit, a "girl-fuelled" movement against the sexualisation of young women, wrote: "Those 'pretty women' that we see in magazines are fake. They're often photoshopped, air-brushed, edited to look thinner, and to appear like they have perfect skin. A girl you see in a magazine probably looks a lot different in real life."

Bluhm hopes to fight back through her work with Sparksummit, which began after the American Psychological Association task force reported the harm to girls' self-esteem caused by sexualised images of young women.

By late Wednesday, the petition, hosted on the social action platform Change.org, had amassed even more names, with the total passing 30,000 signatures.

It chronicles the daily battles faced by her peers over their body image. It reads: "I'm in a ballet class with a bunch of high-school girls. On a daily basis I hear comments like: 'It's a fat day', and 'I ate well today, but I still feel fat'. Ballet dancers do get a lot of flack about their bodies, but it's not just ballet dancers who feel the pressure to be 'pretty'. It's everyone. To girls today, the word 'pretty' means skinny and blemish-free. Why is that, when so few girls actually fit into such a narrow category? It's because the media tells us that 'pretty' girls are impossibly thin with perfect skin."

Bluhm said the "fake" photographs she and her friends see in magazines and adverts has been shown to lead to low self-esteem.

Her petition states: "Girls want to be accepted, appreciated and liked. And when they don't fit the criteria, some girls try to 'fix' themselves. This can lead to eating disorders, dieting, depression, and low self-esteem."

Seventeen magazine said it had invited Bluhm to its offices after seeing her petition. It said in a statement: "We're proud of Julia for being so passionate about an issue – it's exactly the kind of attitude we encourage in our readers – so we invited her to our office to meet with editor in chief Ann Shoket this morning.

"They had a great discussion, and we believe that Julia left understanding that Seventeen celebrates girls for being their authentic selves, and that's how we present them. We feature real girls in our pages and there is no other magazine that highlights such a diversity of size, shape, skin tone and ethnicity."

After the meeting, Julia said in a statement released through Change.org: "The fact that Seventeen's editor-in-chief met with me in person proves that the voices of teen girls everywhere are getting through. While I would still change some of the ways Seventeen portrays girls, I'm encouraged that they're willing to listen to me and the 30,000 people who've signed my petition. Seventeen's invited me to work with them on this issue, which means we girls – Seventeen's readers – are finally being heard loud and clear. It's really exciting."

Bluhm started the petition when she learned that another magazine, Glamour, had decided to limit its use of the airbrush to make people look thinner. After a survey of women found 43% believed magazines should not retouch pictures, Glamour magazine introduced limits for retouching photographs, even if a celebrity or model requested the modifications.

Bluhm said: "A lot of girls read Seventeen magazine. They do a lot to make girls feel good about themselves, stuff like Body Peace. So I thought if they are already doing it, they might like to do more. There have been stories about how much photoshopped images can hurt girls with low self-esteem and eating disorders."

Body Peace asks women and girls to make peace with the body they have and carries interviews with celebrities talking about the issue.

Bluhm's mother, Mary Biter, a social worker and mother of two girls, said she is proud of her youngest daughter.

She said: "She has taken on something that is important to her and it is something that both Robert (Julia's dad) and I have felt important raising two girls. That they are judged by their abilities and abilities and qualities other than their appearance."