As far as Instagram trends go there's not much that's been left untouched – who can forget the thigh gap, the Cara Devigne eyebrows and the turmeric latte? But, just when you thought trends couldn't get any weirder, our feeds are filing up with stomachs contorted into unrecognisable shapes. This trend is named alien yoga.

Officially known as Nauli, alien yoga is said to cleanse the internal organs and tone the abdominal region. The weird alien shape is achieved by emptying your lungs, pulling in your abdomen under your rib cage and isolating and contracting the central, left and right side of the abdominal muscles. 

Despite the potential benefits of this type of yoga, Nauli is not one that's commonly taught or practiced in Western yoga classes.

"Nauli is something that real yoga practitioners tend to keep to themselves, and newer, less experienced teachers don't learn because it's very hard to master as it involves a very different breathing technique," says Simon Borg-Olivier, Director of Yoga Synergy in Sydney.

While today's exercising and training is focused on learning to breathe more, Nauli requires you to breathe less.

To successfully achieve the Nauli technique, you must be able to blow out all of your breath for at least a minute.This goes against the grain for many people.

However, it's not just this breathing technique that may deter people from doing Nauli. It's also about aesthetics.  

"Society has become obsessed with hardening the core and opening the chest, and this technique is not about that at all," says Borg-Olivier.

Borg-Oliver has been practising Nauli himself for the past 50 years, and has also been teaching it to his students for the past 35. However, his classes are the exception rather than the rule.

"Over the last 10 years most people have been doing yoga as a quick fix, and the most popular yoga is not physically what I would call true yoga but more like stretch and strengthening classes taught by relatively new teachers," says Borg-Olivier

While Borg-Olivier has been posting Nauli Instagram pictures of for a number of years, he says that his following is not as large as others and he's probably not "young enough or cool enough" for these to be seen. 

However, the irony of uncensored Nauli photos trending on Instagram is not lost on Borg-Olivier.

"In the 1980s or '90s when I was regularly on television I offered to demonstrate Nauli on The Lifestyle Channel, but I was told that it was not suitable for television audiences because it showed my naked abdomen with the protruding rectus abdominis muscle that I was unfairly told looked too phallic."

So, is "alien yoga" really an achievable trend? Or is it more about slim females using Instagram as a platform to showcase their stomachs?

"Nauli is achievable, but you have to have satisfied some important prerequisites to be able to do it, and most of the people demonstrating it often have learnt it naturally and cannot describe a way of teaching it effectively," says Borg-Olivier.

Pre-requisites for mastering Nauli include the ability to breathe diaphragmatically, to isolate the rectus abdominal muscle and to be able to blow out all your air and hold it for a minute or two.

The dangers of not doing it correctly are notable.

"Some people can end up hyperventilating because they can't master the breathing technique and with that comes a risk of fainting and falling over," says Borg-Olivier.

"Inaccurate breathing can also cause negative pressure changes in the body that affect the blood vessels and potentially the brain."

It's clear to see that Instagramming Nauli is certainly not for the faint hearted, in more ways that one - so, is it something more narcissistic?  Is it more about slim females using Instagram as a platform to showcase their stomachs?

"To a huge extent, it's also about showing off," he says.

Jocelyn Brewer is a psychologist specialising in social media and its impacts.  She agrees that these kinds of Instagram posts are often about people garnering attention in a crowded online space.  

In this instance, it's by appropriating traditional practices into modern fads with new labels.   

"Some people, given the opportunity, will always 'show off' their skills or bodies to get known, seen or recognised,", she says. "While there are genuine people who might be demonstrating the practice with background information, for others it's simply for 'likes'.

"There are millions of people hoping to become 'instafamous' by riding hashtag trends, so they need to get more and more niche or 'out there' to be original and garner attention."

It's unclear if Nauli really is the next trend, or if it will simply fizzle out quicker than it began. Naturally, there will be something else to take its place.

In the meantime, most of us will continue to suck in our tummies for social media pictures, but it certainly won't be to mimic an alien.