The innovative American writer, director and performer Lena Dunham, the creator of Girls and a totemic figure for a generation of young women, has defended herself against claims that a Vogue cover shoot has betrayed her feminist credentials.

Dunham, 27, is known for the nude appearances she makes on her acclaimed HBO show. Her tattooed body is neither honed nor thin, like most of the women shown on television, in cinema or in magazine shoots, so the revelation that Vogue has printed doctored images of her, taken by Annie Leibovitz, has caused reproach. The Photoshopped pictures present a glamorised and slimmed-down version of the star.

Dunham, who was in London last week for the launch of her third series of Girls on Sky Atlantic on Monday, initially shrugged off the attack, mounted on the feminist blog site Jezebel. But on Friday night she told online magazine Slate: "I understand that for people there is a contradiction between what I do and being on the cover of Vogue; but frankly I don't know what the Photoshopping situation is, I can't look at myself really objectively in that way."

Jezebel, which offered $10,000 to anyone who could provide the original unaltered Vogue images, has now revealed that the neckline of Dunham's gown was changed and her face, chin and hips trimmed. Another shot, taken on the street, appears to have been put together like a collage. The cover image, a head and shoulders shot, has been altered to increase the proportional size of Dunham's eyes.

The actress, who plays Hannah Horvath in the bleakly comic series about disillusionment and friendship in the fashionable Williamsburg area of Brooklyn, New York, said she had felt supported by the Vogue team.

"I never felt bullied into anything; I felt happy because they dressed me and styled me in a way that really reflects who I am. And I felt that was very lucky and that all the editors understood my persona, my creativity and who I am. I haven't been keeping track of all the reactions, but I know some people have been very angry about the cover and that confuses me a little. I don't understand why, Photoshop or no, having a woman who is different than the typical Vogue cover girl could be a bad thing."

Answering back, a Jezebel editorial applauded her representation of "normal" women on Girls, but remained critical. "What is not a good thing is when the magazine decides to take that woman and tweak her appearance enough such that she's 'acceptable' for the cover. It undermines the decision to feature that individual in the first place."

Girls does not have an overtly campaigning message, but its four key stars, played by Dunham, Jemima Kirke, Allison Williams and Zosia Mamet, are portrayed as complex and difficult personalities rather than as conventionally appealing and kooky. As a result it was welcomed by critics and feminists when the show was broadcast in 2012.

The sex scenes in the show, as Dunham told London journalists last week, are rarely about pleasure, either for the characters or the television audience. "We usually work out the shapes beforehand in all those scenes," she said, revealing that she and her producer and co-creator Jenni Konner actually demonstrate the positions for other actors involved in such sessions. The show, Dunham argued this weekend, is a dark and honest enough look at sexuality and gender to allow her to have fun elsewhere. "A fashion magazine is like a beautiful fantasy," she told Slate. "Vogue isn't the place that we go to look at realistic women, Vogue is the place we go to look at beautiful clothes and fancy places and escapism, and so I feel like if the story reflects me and I happen to be wearing a beautiful Prada dress and surrounded by beautiful men and dogs, what's the problem? If they want to see what I really look like, go watch the show that I make every single week."

Earlier this month Dunham was involved in a row in Los Angeles between a journalist and the American comedy producer Judd Apatow, who brought Girls to HBO. At a promotional event a male journalist asked Dunham why she included so many scenes of herself having sex in the show. Dunham replied: "It's a realistic expression of what it's like to be alive. If you're not into me that's your problem." But Apatow, who made the films Knocked-Up and The 40 Year Old Virgin, stepped in to ask the journalist whether he had a girlfriend and if so, whether she liked him.

Girls, which is made by a group of well-heeled white young women, has also been criticised previously for its lack of ethnic minority cast members. In response to those attacks, Dunham said last week, "We heard all of that and really felt it deeply," adding: "I really try to educate myself in those areas."

Jezebel, which is owned by Gawker, has conceded that Leibovitz is known for using composite images. When she photographed Elizabeth II she superimposed the monarch on a field. The photographer also controversially shot scantily clad pictures of a 15-year-old Miley Cyrus for Vanity Fair in 2008.Jezebel argues that while men are shown with flaws "women are supposed to be perfect". Especially, it now seems, when it comes to the political decisions they make in the glare of the media.