IStock Photo 4068393 © Reid Veto

More than 40% of women have a negative body image, according to a 2009 survey by Glamour Magazine. And is it any wonder? From the classic Barbie doll—who, were she a real person, would tip the scales at 110 pounds—to the fashion models filling the pages of magazines with their typically 110-pound, 5-foot, 9-inch frames, images of pin-thin women are everywhere. Meanwhile, the odds that a woman aged 20-29 weighs less than 130 pounds are just 1 in 3.1. For women in their thirties, those odds decrease to 1 in 4.41.

Women and girls spend a lot of time worrying about weight—and the media spends a lot of energy telling them why they should. High profile weight-loss programs such as Weight Watchers, Jenny Craig, and the television show "The Biggest Loser" all send women scrambling to their scales. Fashion and beauty magazines are filled with slim-down strategies and “before and after” photos. One study found that 69% of adolescent girls surveyed reported that magazine pictures informed their idea of the perfect body size, and that 47% wanted to lose weight because of these pictures.

And oftentimes these photos may have been doctored. In one of the more recent “Photoshop” controversies, Self Magazine ran a cover photo in September of Kelly Clarkson that appeared to be enhanced to make her look skinnier. Ironically, the magazine ran this text next to the photo: Kelly Clarkson “Stay True to you and Everyone Else Will Love You Too!”

There’s also been some backlash against the scrawny “perfect” body depicted in the media. In 2002, actress Jamie Lee Curtis got More magazine to take photos of her in her underwear showing her true self. The next page in the magazine showed her gussied-up and slim with an explanation that it took 13 people and three hours to make her look that way. And Dove soap started its “Campaign for True Beauty” not that long ago, which features regular-sized women. Even Glamour Magazine got into the act this year when it featured a model with a little bit of belly fat. Readers loved it and inundated the magazine with fan letters.

But concerns about women’s weight are not necessarily unwarranted. According to the Centers for Disease Control and Prevention, the prevalence of obesity among adults in America has doubled since 1980, with more than 35% of women weighing enough to be deemed obese in 2006.

It’s important to note, though, that the number of pounds a woman weighs does not have the final say when it comes to whether or not she’s overweight. Body Mass Index, a calculation based on ratio of height to weight, is a more reliable marker of body fat (you can calculate yours here). Taking into account things like muscle mass and physical fitness, healthy bodies for women come in a variety of shapes and sizes.

Ignoring the media’s onslaught of skinny jeans and diet pills can be difficult. But according to the women surveyed by Glamour Magazine, healthy lifestyle choices—and a positive attitude—can be keys to improving body image. Of the 16,000 women questioned, 96% said that exercising made them feel better about their bodies, while 97% reported getting the same outcome from eating healthy, balanced meals.

As it turns out, having a positive body image may even improve the likelihood of a woman achieving a healthy weight. In a recent study, researchers at the University of Minnesota found that overweight teen girls who felt good about their bodies were less likely to gain weight as they entered adulthood.