Can You Pass the Belly Button Challenge? If Not, You Need to Lose Weight

A new craze involving a simple test to show if you need to lose weight.

Thousands of people (in China) are posting selfies to show whether they can touch their belly button by reaching around their backs.

Since Wednesday, the 'belly button challenge' has received more than 130 million hits and is now the number one trending topic on Weibo, the Chinese version of Twitter.

The challenge post claims that if you can complete the challenge, it proves you have a good body, but if you cannot, you need to lose weight.

Experts say that the challenge does not necessarily mean that you have a super-fit body, but could also mean that you have long arms or are very flexible.