Flying on a plane may ruin your diet, even when you are hardly tempted by the in-flight food.

The meals served are laden with calories, not to mention being in the air tempts you to eat more, says a new book Gastrophysics: The New Science Of Eating.

The book cites research which suggests that the average Briton consumes nearly twice the recommended daily intake of calories while heading to their destinations.

Here are some warnings about inflight food from author Professor Charles Spence and other experts.

1. It contains more sugar

Lower cabin air pressure, dry cabin air and the loud engine noise all contribute to our inability to taste and smell food and drink.

Sound suppresses sweetness perception so about 15 to 20 per cent more sugar is added to the foods we eat while in the air to give the same taste perception.

2. You eat more due to boredom

With nothing else to do, food becomes an appealing distraction, particularly when it is free, says Prof Spence.

This is why passengers ask for second helpings of bread, desserts, alcoholic drinks and fruit juices.

Watch inflight entertainment to relieve the boredom? That may not work.

"It is not uncommon to find people eating as much as a third more food with the TV show on," he said.

3. The more alcohol you drink , the more dehydrated you get

The air in an aircraft is very dry and, coupled with the diuretic effect of drinking alcohol, those who down alcoholic drinks may become dehydrated much faster than on the ground.

4. The meals are not fresh

Most meals are made between 12 and 72 hours ahead of the time that they are served on the plane.

Celebrity chef Gordon Ramsay, who has worked for airlines for 10 years, says he has sworn off airline food. He goes for a snack at an Italian bar in the airport before his flight.

5. Asian airlines aren't as bad

The anonymous founder of Airlinemeals.net gives the thumbs up to meals served by Asian carriers.

"I would say airlines from Asia get the best results... Singapore Airlines, Japan Airlines, Cathay Pacific, Thai Airways International, Emirates... and from my own experiences, I would like to add Qatar Airways and Vietnam Airlines," he said. "'They're all top notch."