Pages from the 'A4 waist' debate: (Left) Women practice yoga in Hangzhou, East China's Zhejiang Province, on March 16. (Right) Instagram user "be.arum" from Seoul, South Korea, holds a clipboard with a piece of paper that reads, "You don't need A4 paper to prove that you are beautiful." Photo: IC

The "A4 waist challenge" - China's latest body image trend - is facing heavy criticism worldwide on social media where many aim to show that beauty is not paper-thin.

The waif-obsessed craze, which challenges people to hide their waists behind a vertical piece of A4 paper (21 centimeters wide), has prompted disdain not only among Chinese, but also from comrades in South America, Europe and the US.

Their responses, hashtagged #stopa4waist to #youarebeautiful, among others, on Instagram and Twitter, show women and men alike holding paper of various sizes bearing messages of encouragement that at the same time manage to cut the standard of beauty to size.

"Don't hide behind a piece of paper, you are beautiful!" an Instagram user in Germany posted.

"Your body is sacred. You're exactly the way you supposed to be," an Instagram user posted in Brazil.

Instead of paper, some held up their university diplomas, while others complimented their messages by holding up a middle finger.

The A4 waist challenge first picked up momentum with endorsements from - go figure - Chinese celebrities, such as actresses Yuan Shanshan and Wang Likun.

Soon, other groups and organizations jumped on the bandwagon.

Firefighters in Zhashui County, Shaanxi Province, posted their own A4 waist photos to show off their muscles with messages such as "union is strength."

Chinese were quick to criticize the trend for being an unrealistic standard of beauty.

"Using a piece of paper to measure your beauty reminds of like foot binding in feudal times," Sina Weibo user "Hannibal Bimao" said.