If you can stand straight with your knees together and see a space between your upper thighs, you have what thousands of teen girls are willing to starve themselves for.
The thigh gap, as it is known, is a small, hollow cavity with a huge following on social media. You can follow supermodel Cara Delevingne's thigh gap on Twitter or peruse thousands of thigh gaps on Tumblr with images of ultrathin women in bikinis, hiked up skirts and lingerie, all baring thighs so thin they don't touch. The photos, shared by young women, come with captions like, "Three more inches to go" and "All I want in life is a thigh gap."
Women have long been bombarded with unrealistic images of beauty and digitally altered bodies. A decade ago, teens flocked to pro-anorexia websites that shared similar photos and tips for disordered eating. But the thigh gap is the first "thinspiration" voice in social media, where sharing with friends spreads and fuels the obsession.
The thigh gap's social media presence is, in fact, a "perfect storm," says Debra Milinsky, a licensed clinical social worker of the Feminist Therapy Connection in Berkeley, Calif.
"Girls are at a developmental stage where their bodies are changing, and when it comes to what they're supposed to look like, they're most likely to listen to their peers," Milinsky says. "That's what the Internet is all about. Seeking community."
Of course, not all girls want to join that particular one. Maya Sweedler of Los Gatos, Calif., calls the thigh gap trend "awful."
"I can't believe what some girls are encouraging each other to do, to be so unhealthy and all look the same," says Sweedler, 16.
She also points out that nature plays a role.