Women are holding up pieces of paper to show how skinny they are on social media

ryz.jr/Instagram

A trend is sweeping the internet where women (and some men) are holding up pieces of 8.3-inch-wide A4 printer paper to show how tiny their waists are.

It's called the #A4Waist or #A4WaistChallenge, and according to The New York Times, it started in China where there are hundreds of photos on social media platforms like Weibo, Weixin, and WeChat.

Weibo

This woman's A4 challenge picture on Weibo has been liked by nearly 130,000 users.

The pieces of paper are held vertically in front of the women's torso. The point? To show that their waist is smaller than the 8.3 inch paper width.

Doing the math, that would mean these women have roughly a 25 inch waist, if not smaller - much tinier than the 35-inch average American waist, as The Times points out.

The challenge is also spreading across the world as more and more people become aware of the trend. Searching Instagram and Twitter, there are now hundreds of posts tagged #A4Waist.

And while some people are posting in earnest, others are using the hashtag to criticize the viral challenge.

Freelance writer Stevie Martin had one of the best responses:

Last year, a similarly viral stunt took hold on Chinese social media where women and men were wrapping their arms around their waists - it was called the belly button challenge, and the point of the trend was also to brag about how skinny they were.

But it should be remembered that being slender does not mean you're healthy.

"There are lots of more scientific - or at least kind and loving - ways to measure your body and determine your health status," Dr. Wendy Bazilian, author of "The SuperFoodsRx Diet," told People Magazine. "Beautiful bodies come in many sizes."