First it was the 'Kylie Jenner Lip Challenge.' Now it's the 'Belly Button Challenge.'
According to ABC News, the challenge blew up on a social media site in China and has been growing ever since.
The basic concept of the challenge is to reach behind your back and touch your belly button. The point of the challenge is to show off that you're in-shape and have a fit body.
Many medical experts are concerned that the challenge may be fueling body issues.
"Social media challenges like these can stoke comparison and body insecurity, especially for those struggling with disordered eating," National Eating Disorder Association program director Claire Mysko told ABC News. "We advocate for body positivity challenges, which are empowering and encourage self-expression, not self-criticism."
One doctor added that looks can be deceiving and don't necessarily depict your true health.
Someone skinny could be "just as unhealthy as someone who weighs 400 pounds."
"It's concerning people are using body differences to promote possibly unhealthy eating practices or ways in which people can compare themselves negatively to others, which has been linked to depressive symptoms," another doctor added. "It's one more indicator of 'I'm not good enough,' 'attractive enough,' or 'thin enough,' and it's harmful."