No one really knows how or why irritable bowel syndrome (IBS) develops, but gastroenterologist Brennan Spiegel from Cedars-Sinai hospital in Los Angeles has outlined a weighty new hypothesis.

In a paper published in The American Journal of Gastroenterology, Spiegel argues IBS is triggered by the body's inability to manage gravity.

"Our nervous system also evolved in a world of gravity, and that might explain why many people feel abdominal 'butterflies' when anxious," says Spiegel.

It is also involved in the regulation of our blood pressure in response to gravity.

"Dysregulated serotonin may be a form of gravity failure," argues Spiegel.

All of these conditions could be explained by the body's inability to properly manage the force of gravity.

Without direct research, Siegel says the gravity hypothesis is just a "thought experiment".