Who, What, Why: How long can someone survive 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 a little less than a mile from a main road in northern Sweden. Police say the temperature in the area had recently dropped to -22F (-30C).
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.
- It is possible to survive for about 60 days without food - but usually in warmer conditions
- Snow on the car may have created an "igloo effect"
- Being inside a car might have conserved calories
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.
Survival through hibernation
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.
Catherine Collins, spokeswoman for the British Dietetics Association explains that "the body can remodel during starvation to minimise the amount of calories it needs".
When the body stops getting food, it has to live on the stored sugars. The liver and muscles store glucose - the primary fuel source - as glycogen. This glycogen can then be converted into glucose.
When this runs out, fat is then converted into a secondary energy supply called ketone bodies. After the fat runs out, she says, the body must take recycled protein from the system and eventually from the muscles to convert to energy. But this, she says, is "very expensive" fuel for the body because "it's wasting important tissue reserves".
"It's like being in a cold house and burning Chippendale furniture instead of firewood," she says.
However, the resulting muscle loss slows the body's furnace, causing it to burn calories at a slower rate. "So whatever calorie supply you have will last you longer," she says.
"In a way you're trying to eke out what you've got left to help you survive."