Hundreds of thousands of girls in China are enthusiastically responding to the trend of using A4 paper to measure their waist size and sharing the secret to having a small waist.

A girl raises her hand in a V sign while doing the waist-baring challenge with A4 paper. Photo: CEN

According to The Sun, those who want to experience the waist challenge will have to hold a piece of A4 paper, only 21cm wide, and place it vertically in front or behind their waist. If the paper covers the waist, it proves that the person has a standard waist.

Many Chinese people have joined in on the trend by sharing photos of themselves with A4 sheets of paper on Weibo, claiming that their goal of having a slim waist like that is completely achievable.

"My waist is smaller than this A4 paper. I'm A5 size," one member boasted.

Some dieting girls shared photos of Chinese models doing the A4 paper challenge along with some tips to help them lose weight.

Two beautiful girls join the A4 trend. Photo: CEN

The waist-baring challenge has received some criticism, although it has been well received. Many people believe that it puts pressure on women, forcing them to strive for goals that are difficult or impossible to achieve.

An angry member wrote: "A4 paper waist challenge? What nonsense."

Last year, young Chinese people also went crazy over the trend of touching their belly buttons to show off their perfect waist. The trend means "anyone who can put their arms around their back and touch their belly buttons proves to have a beautiful body". Many people try this challenge for fun, but experts disagree, pointing out many negative aspects of this strange trend. They say it is similar to encouraging eating disorders and "distorting" society's beauty standards. In addition, "touching the belly button" does not mean that the participant has a slim body, but only that they have long and flexible arms.

A girl shows off a photo of herself doing the belly button challenge last year. Photo: People's Daily

According to ngoisao.net