Chinese 'bellybutton challenge': Why are people posting pictures reaching behind their backs on social media?

Topic has had more than 130 million hits in just two days

The craze is being emulated millions of times (Weibo)

A new online craze from China is taking the internet by storm as thousands of people continue to post selfies of themselves doing ‘the bellybutton challenge’.

Since Wednesday, the topic has received more than 130 million hits and has been the number one trending topic on China’s version of Twitter, Weibo.

The challenge sees people attempting to touch their bellybuttons by reaching around their backs as a way to prove whether they have a ‘good body’. If not, the next step is to lose weight until the challenge can be completed.

Although most have been doing the challenge for ‘fun’, an expert warned of bizarre trend’s 'dark side' yesterday.

Jolene Tan, a senior manager at Aware – an organisation in Singapore which champions women’s rights – said: “Quirky poses and pictures can be fun but, sometimes, they also become expressions of competitiveness or insecurity.”

She added that the trend seemed to be “one more way of scrutinising women’s bodies to see whether they are ‘good enough’” and warned: “We need to do more to promote acceptance of diversity in women’s bodies.”

Experts, however, say the challenge does not necessarily mean that participants have a super-slim body – but rather that they are simply flexible and have long arms.

And it’s not just women who are embracing the trend. One young man – with a slightly curvaceous figure – has attempted the craze which has, so far, garnered over 10,000 likes.