If you're over 50 and pick up a copy of Vogue magazine, don't expect to see someone like you peering back from the cover. Despite having a readership that's one-fifth women over 50, the magazine has only featured one woman over 40 on the cover in the past year — Halle Berry, then 43, who appeared on the September 2010 issue.

Needless to say, nary a wrinkle was in sight. More typical are younger celebrities, including Lady Gaga, 25, and Natalie Portman, 29.

A new study finds that this absence of older women isn't limited to Vogue, or even to magazine covers: An analysis of editorial and advertising images reveals that despite proportions of older readers ranging as high as 23 percent, fashion magazines portray women over 40 sparingly, if at all. Even in magazines geared toward aging baby boomers, the images collectively present a thin, youthful, wrinkle-free ideal that's impossible to maintain later in life. Now experts are saying the ideal threatens to cause older women to abandon their sexuality.

"It does lead to problems of negative body image," said study author Denise Lewis, a gerontologist at the University of Georgia who reported the results in April in the Journal of Aging Studies. "It leads to issues that have people denying aging, so going to great lengths to continue to look like that ideal of a youthful person." [5 Reasons Aging Is Awesome]

Aging and eating

The most age-friendly publication Lewis found, Essence, has a reader base that is 22 percent over age 50, but only about 9 percent of the women on the magazine's pages are over 40. The magazine that most closely matched its readership to its images was Instyle, which has an audience that is 11 percent 50 or above. Just under 8 percent of the women in the magazine were over 40.

"Even women that we knew to be over 40 didn't look like they were over age 40," Lewis told LiveScience. [Sidebar: How Many Older Women Are In Your Favorite Fashion Magazine?]

It's no secret that magazines and other media prefer their models youthful, thin and often Caucasian. But studies of the media's influence on women's health typically focus on younger women. In the most famous study, published in the British Journal of Psychiatry in 2002, Harvard Medical School psychiatrist Anne Becker compared the adolescent girls of Fiji before and after television made its debut on the island and found that eating disorders and dieting spiked when TV was introduced. The traditionally rotund girls told Becker and her colleagues they wanted to lose weight to look like the skinny Western girls on TV.

But eating disorders aren't only the domain of younger women, Lewis said. Older women have not been studied as frequently, but two population-based studies in the 1990s estimated that between 7.2 and 7.7 per 100,000 women between the age of 40 and 59 have anorexia nervosa, an eating disorder characterized by an inability to maintain 85 percent of average body weight per height. That's far fewer than the 70 or so per 100,000 teen girls with anorexia. However, a 2001 study of the binging and purging disorder bulimia nervosa found that about 1 percent of middle-age women have the disorder, comparable to the 0.9 percent of women between the ages of 18 and 25 with bulimia.

According to a review of eating disorder research published in June in the journal Clinical Psychology Review, about 4.5 percent of middle-age women have eating disorders, and some studies have found increased admissions of middle-age women into eating disorder clinics in the past decade.

The same review found only two earlier studies that investigated the link between media consumption and eating disorders in older women. A study published in 2008 found that pressure from family, peers and media was linked with a desire for thinness and disordered eating. Another study, published in 2003, found that family pressure was the most influential path to an eating disorder, though perceived media pressure had a small to medium influence as well.

Internalizing ageism

Some researchers are concerned about more subtle influences, however. Even in magazines geared toward older women, such as More magazine, signs of aging are often airbrushed out, Lewis said. Perhaps not coincidentally, anti-wrinkle treatments are soaring in popularity.

"You have the mixed message in More magazine with all the anti-aging creams and Botox," Lewis said, adding that she did admire More's attempt to reach an older audience. Even so, she said, the message is "either mask your age, or you're so old you're parked in the corner."

Peggy Brick, a sex educator and co-author of "Older, Wiser, Sexually Smarter: 30 Sex Ed Lessons for Adults Only" (Planned Parenthood of Greater Northern New Jersey, 2009), says she worries that the media's view of older people as invisible — and certainly not sexual — contributes to older adults simply "giving up" on their sexuality.

"I'm trying to get them to fight the stereotypes that sex is simply for the young and the beautiful, and that old is ugly and nonsexual," Brick said of her senior students. "I think that some people have really absorbed those messages."

Research has shown that, in fact, older people have rewarding sex lives, with 38 percent of men and 17 percent of women between the ages of 75 and 85 still sexually active.

Public pushback against the thinness ideal has inspired some youth-oriented fashion magazines to occasionally feature "plus-sized" models. Even high-fashion Vogue featured three curvy women (models Tara Lynn, Candice Huffine and Robyn Lawley) on the cover of its Italian magazine in June. Could consumer pressure lead to similar breakthroughs with older women, especially with the baby boom generation aging? Lewis thinks so.

"I do think that boomers will bring that change to fashion," Lewis said. "The baby boomers have historically not done very much in a quiet way."

You can follow LiveSciencesenior writer Stephanie Pappas on Twitter @sipappas. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.