Who, What, Why: How long can someone survive without food?

A Swedish man, found in a car buried under snow, says he survived for two months without food by eating handfuls of snow. But how long can people go without food?

The circumstances surrounding Peter Skyllberg's survival are still being investigated. However, photographs taken of the inside of the car show empty food and drink wrappers, which could mean the 44-year-old had some sustenance.

The car was found on Friday at the end of a forest track more than 1km (0.6 miles) from a main road in northern Sweden. Police say the temperature in the area had recently dropped to -30C (-22F).

Skyllberg says he had been inside the car since 19 December 2011.

Experts believe it is possible for the human body to survive without food for up to two months.

It's not the first example of humans subsisting on next to nothing for long periods of time.

Japanese hiker Mitsutaka Uchikoshi survived 24 days in 2006 without food and water after he went missing during a climbing trip in western Japan. He was found with a body temperature of 22C (71F) - nearly 15C below normal. After being treated for severe hypothermia and other health complications Uchikoshi returned home, leaving some doctors puzzling over his miraculous recovery.

Last year, a 56-year-old woman from British Columbia survived nearly 50 days in the Nevada wilderness on trail mix, sweets and stream water after being stranded in the mountains while her husband went in search of help. Hunters found Rita Chretien conscious and able to speak, although she had lost 20-30lb as a result of the ordeal.

The American illusionist David Blaine spent 44 days in 2003 suspended in a glass box by the River Thames in London without food. In the 1940s, Mahatma Gandhi survived 21 days on sips of water during a display of civil disobedience.

But even in the chronicles of food and water deprivation, Skyllberg's recent 60-day stint is an extreme case.

"It is at the bounds of possibility but not completely untenable," said Dr Mike Stroud, senior lecturer of Medicine and Nutrition at Southampton University.

Stroud, who accompanied veteran British adventurer Sir Ranulph Fiennes across the Antarctic, said it was possible to survive 60 days without food.

"That is about the time hunger strikers in prisons tend to die," said Stroud. "But they are normally in warmer conditions." In 1981, Republican prisoner Bobby Sands died in Northern Ireland's Maze prison after a hunger strike lasting 66 days.

There are a number of factors that can influence a person's ability to survive, says Stroud, such as the way in which the body's metabolism slows down to conserve energy.

"The average resting human body, doing absolutely nothing, produces about 100 watts of body heat, which could function a light bulb," he says. "But under these circumstances the body will begin to make less and less heat to keep you warm. That's where a heavier body would have more of an advantage."

Stroud also says the amount of body fat a person has at the beginning of the ordeal may not count as much as one might imagine.

BBC news