Jet lag can make you fat, thanks to bacteria disturbed by travel

Jet lag can make frequent flyers fat, researchers have found.

A study published in the journal Cell found that all living organisms, including bacteria in the body, have biological clocks that can get thrown out of sync by international travel.

In humans, the result is jet lag. But at the microbial level, the result could be a gut full of the wrong kinds of bacteria - including species that promote obesity.

Researchers looked at the microbiome, or bacterial populations, in rodent and human subjects. The abundance of different bacteria (and their activities) changed based on the time of day the sample was taken.

The researchers then messed with their subjects' biological rhythm, flying two human subjects to Israel and manipulating the mice with lights and meals.

The jet-lagged mice started putting on more weight than those that hadn't "travelled", even though they were on the same diet. When the researchers transferred gut bacteria from jet-lagged mice to healthy ones, the new mice saw the same effect.