Celebs' sexy pics spark 'ab crack' trend

Tell the thigh gap to move over, the “ab crack” is making its mark on Hollywood stars and social media.

The ab crack was recently coined by Cosmopolitan as a “new core look” and an “irrigation ditch divide.” It is being flaunted all over social media by of the most popular celebs.

Emily Ratajkowski, Bella Hadid and fitness guru Jen Setler have shown off their super fit bikini bodies. In their photos, a noticeable line appears down the center of their torsos, which is only visible due to their very flat stomachs.

However, body image expert Sarah Maria, told FOX411 the ab crack becomes a breeding ground for body-image dissatisfaction.

“Any time people obsess over a particular body part – its size, shape, or contouring, it is a breeding ground for body-image dissatisfaction,” she said. “People who don’t have ab cracks feel like they should have them in order to be beautiful and then are inclined to starve themselves and workout obsessively in order to get one.”

Dr. Marc Siegel, of the Fox News Medical A-Team, said the ab crack is a deceptive goal for people to attain.

“There is nothing healthy about the ab crack except insomuch as thin is generally healthier than heavy,” he explained via email. “But to the extent that excess fascination with body tone leads to obsessive use of isometric (weights, etc.) as opposed to regular use of cardiovascular exercise (running, elliptical, bike, rowing), then I would call the ab crack potentially unhealthy.”

And Maria pointed out this phenomenon is part of a body image obsession that affects both men and women.

“I would say that the ab crack phenomenon is simply another version of the same old needless body-obsession that plagues most woman and many men.”

It’s far from the first time a celebrity look has caused a style trend. Back in April 2015, teens who wanted to imitate Kylie Jenner’s surgically enhanced lips swelled up their lips by sucking into a small glass. The trend caused bruising and considerable pain.

And in 2013, the thigh gap took over the Internet, partially thanks to the slim legged looks models were showing off on the runway. Experts said at the time the thigh gap was virtually impossible to achieve and risky to try.