Body image experts have warned young women to avoid a “harmful” social media trend that pushes people to measure their waists against the width of an A4 piece of paper.

The trend involves women trying to prove that their midriff is of equal or lesser width than that of an A4 sheet of paper on portrait rotation, and it has taken Chinese social media in by storm.

It had been reported that tens of thousands of people took to the challenge on Chinese social network Weibo, which is similar to Twitter.

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“#A4 waist. The summer is coming OMG,” @lizzy_emotion wrote on Twitter, accompanied by photos of her partaking in the challenge.

A sheet of A4 paper, defined by the International Organisation for Standardisation (ISO), measures 8.27 inches (21cm) wide and 11.69 inches (29.7cm) long.

The circumference of a size 6 waist in Australian measurements in 23 to 24 inches (58-60cm).

This lady’s waist is visibly skinnier than the A4 paper.

Body image experts told The New Daily that the trend is harmful and unhealthy.

“It’s a completely unrealistic standard and very dangerous. Particularly for Australian women,” Body Positive Australia body image expert Sarah Harry said.

“Comparing yourself with anything, or somebody else body is a really unhelpful behaviour.

“It just usually helps people feel more dissatisfied with their own body.”

University of Canberra clinical psychologist Dr Vivienne Lewis said the challenge was a recipe for disaster.

“Getting hung up on using an A4 piece of paper to measure if you’re thin enough is not a very safe thing to do,” Dr Lewis said.

“Any form of body measurement is potentially dangerous. You need to look to a healthy body and that comes in all different shapes and sizes.

“A majority of people are not going to fit behind an A4 page. So you’re actually setting yourself up to feel bad about yourself.”

A boyfriend posts about his girlfriend’s A4 challenge success.

Experts say the trend is dangerous.

The A4 waist challenge is just the latest in a series of alarming health and beauty fads coming out of China.

In January 2016, Chinese women began taking pictures of themselves holding pens under their breasts in an attempt to illustrate how feminine they are.

Another trend saw women bending their arms around their waists, with reaching their belly button from behind signifying being suitably skinny.

This was known as the “Belly Button Challenge” (watch the video below for more on this).

“You don’t need an inanimate object or a scale to tell you how to feel about yourself,” Ms Harry said.

“I warn against doing these challenges because they don’t help people develop a calmer or more peaceful body image.”

In Australia, the controversial “thigh gap” trend garnered similar criticism in 2013.

“Thigh gap” is a female beauty standard that saw women striving to ensure they had a visible gap between their thighs, just beneath the vagina.

Dr Lewis said it was worrying that so many trends pushing the message “the thinner you were the better” had been emerging of late.

Watch people attempt the ‘Belly Button Challenge’: