My daughter Talia, who is 12, beams at me, a devilish smile spreading across her face. “Don’t worry, Joel,” she tells her 9-year-old brother, “girls are supposed to be skinny.”

Joel’s brow furrows in suspicion, but this bulletin isn’t really directed toward him. Talia pauses. She is awaiting the dismayed response of her parents — the reaction that inevitably follows when the conversation steers down this path. “Boys,” she continues, “are supposed to have muscles.” She is still smiling.

I am appalled. “You don’t actually believe this, do you?”

Yet, it seems that Talia does at least partly subscribe to these beliefs, and what’s worse, this year she’s taken to scrutinizing her perfectly proportioned body and beautiful face with a critical eye. “I wish I didn’t have daddy’s eyebrows,” she complains at dinner one night. “I wish my waist were thinner,” she sighs. Talia seems to have absorbed more than academics in middle school.

Talia has reached the age of bat mitzvah, an age when peers exert a strong influence, and a time of life sometimes correlated with “a precipitous drop in self-esteem” for girls, says Esther Altmann, a psychologist and expert on body image in the Jewish community. “Middle school girls are exquisitely aware of their strengths and weaknesses vis-à-vis their peers and often redirect feelings of social anxiety and competition onto their bodies.”

Altmann suggests that parents help daughters “identify problematic comments from peers about dieting and their bodies as annoying chatter so that girls can distance themselves and not get caught in a worrisome vortex of not being thin enough.”

Talia grew more aware of appearances at her Jewish camp last summer, where a policy prohibiting “body talk” apparently backfired. “I wondered what people would have been saying had they been allowed to speak,” she says. The issue intensified about six months ago, when Talia started praising “thinness” as if it were a divine trait. When I aim to adjust her skewed values, she suggests: “Maybe you should write a column about this.”

Yet when I turn to religious sources for guidance, the effort is not entirely successful. Talia apologizes that she may not be “Jewish enough,” to be moved by the concept that “we are all created in God’s image.” When I offer a rabbi’s suggestion that our bodies are like sanctuaries, each sacred and deserving of respect, Talia says: “Hmmm, that’s weird.”

What about the role model of Vashti, the first queen of the Purim story, who fiercely rejected King Achashverosh’s request to dance before his friends? Talia smiles. I sense mischief. “Vashti, she was pretty, right?” she says.

I roll my eyes. “The point is you can learn to say no, Talia. You can learn to say no to ideas about the body that aren’t healthy.”

We have better luck with “Pretty Sexy Sassy,” a new documentary about body image produced this year by the high-school interns at Ma’yan, a program of the Jewish Community Center in Manhattan. Webisodes of the video, available on the organization’s website (mayan.org), flip between disturbing images from the media and interviews with girls. Talia stretches out on my bed, her eyes glued to the screen, her mouth keeping up a steady stream of chatter.

She talks of how she tries to draw women with “skinny waists, wide hips and really long legs. It looks pretty, and most of my friends would agree,” she says. When I beg to differ, she says, “All the models look like that. If you look up how to draw cartoon girls, that’s what you’ll learn.”

“Do you want to look like a cartoon?”

“Yeah, I kind of do.”

She quiets as the documentary continues. “You can’t just turn off the TV. There are ads on the newsstands. There’s no way to escape it,” says one of the teenagers on the screen. Another teen notes grimly, “Watching my friends struggle with eating disorders or depression, it’s so real. And it’s not something they can control.”

The webisodes reveal the magic of digital alteration, and Talia is dutifully impressed with a model’s transformation. She exclaims, “Look how flawless she appears!” Also this: “I’d like to be ‘Photoshopped.’”

As expected, Talia is smiling. I am not. Still, I am hopeful. We’re on high alert to the power of peers and the press. And although my daughter admires the absurdly slender frame of Barbie, she still reads this column, giggling gleefully as she exclaims: “Mirror, mirror on the wall, who’s the fairest of them all? Talia!”

Elicia Brown’s column appears the second week of the month. Email: eliciabrown@hotmail.com.