The key to beating jet lag on long haul flights is not to eat the airline food, according to scientists.

The advice for international travellers comes from a study that shows the timing of meals has a much bigger effect on the body clock than previously thought.

Avoiding food on long haul flights, then eating on arrival, could cut the time it takes to adjust to a new time zone.

Scientists have known for decades that meal times can affect the body clock, which has a natural period of about 24.2 hours. But they have always thought that the key factor is light.

Now a team at Beth Israel Deaconess Medical Centre, Boston, Massachusetts, has discovered a second “food-related clock” which can override the “light-based” master clock when we are hungry.

The findings are reported in the journal Science.

Prof Clifford Saper, the report’s senior author, says: “If, for example, you are travelling from the US to Japan, you are forced to adjust to an 11-hour time difference.

“Because the body’s biological clock can only shift a small amount each day, it takes the average person about a week to adjust to the new time zone. And, by then, it’s often time to turn around and come home.”

But, he adds, by adapting eating schedules, an international traveller might be able to engage his second “feeding” clock and adjust more quickly to the new time zone.

“A period of fasting with no food at all for about 16 hours is enough to engage this new clock,” says Prof Saper, who worked with Dr Patrick Fuller and Dr Jun Lu.

“Simply avoiding any food on the plane, and then eating as soon as you land, should help you to adjust – and avoid some of the uncomfortable feelings of jet lag.”