How Many Days Can You Survive Without Food?
While a person cannot survive longer than three or four days without water, lack of food won't result in immediate death. How long a person can survive without food depends on a variety of factors, but experts believe that it's perfectly possible to live for several weeks without the ingestion of any nutrients.
Features
The body feeds primarily on glucose (blood sugar), which comes from the carbohydrates consumed in the daily diet. When food is not consumed for more than four days, your body turns to your stored fat as a source of energy. Once the fat storage is gone (how long it takes depends on your initial weight), the body will start consuming your muscles in order to stay alive. Muscles on the arms and legs are the first to go, followed by other, more important muscles. Because the heart is a muscle, this will eventually lead to cardiac arrest and death. If food is provided in time to save the person's life, there can be permanent heart damage, such as cardiac arrhythmia.
Potential
Mental preparation and awareness have a big impact on how long a person can subsist without food. When the will to survive kicks in, people can survive longer. Meditation also helps, which is why people who choose to fast have a better chance of surviving longer than those who are forced to eat. Mental preparation can also help those without food calm down, lower their metabolism and learn spend less calories.
Function
The human body needs a minimum of 1,500 calories a day to function properly, although some sources quote 2,000. This is known as the Basal Metabolic Rate (BMR) or amount of energy the body needs to maintain full function of all organs. While it's possible to survive on much less, medical problems will eventually appear, as the body shuts down certain functions in order to stay alive. Prisoners in concentration camps during WWII survived on a diet of about 300 to 600 calories per day, which resulted in a myriad of diseases, as well as starvation for many. Prisoners on the lower end of the caloric scale lost an average of 9 lbs. per week, and most died within three months.
Expert Insight
People all over the world have survived for what seem like extraordinarily long periods of time without food. Magician David Blaine survived for 44 days without any food while suspended on a glass box over the River Thames. Blaine survived on 4.5 gallons of water a day and lost a total of 54 lbs. because of the ordeal. Mahatma Gandhi survived a three-week fast when he was 64 years old. Protesters and political prisoners have survived for up to 73 days without any food, although most of those who went beyond 40 days succumbed in the end.
Facts
How long a person can survive without food has to do with a series of factors, including initial weight, health and amount of body fat. Muscle burns more calories than fat, even at rest, so leaner people will last for less time without food than those who are even slightly overweight. Activity level also has an effect on the length of survival. As the body burns more calories when at work, those who are relatively inactive will survive longer. Colder temperatures require the body to burn more calories in order to stay warm, so the time you can survive without food and nutrients is a lot shorter.
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