If you avoid waterandfood, however, survival time diminishes to about one week.
The timeframe for survival without food is not exact, however.
Aside from a lack of robust scientific data on the matter, every person is different.
Verywell / Laura Porter
Personal factors like your starting body weight play a role.
Survival Time Without Food
Your body is very resourceful.
When you go without food, your body can obtain energy and fuel from its own fat.
If needed, it can also use muscle stores.
Eventually, however, your body runs out of the nutrients it needs to survive.
Peer-reviewed medical reports regarding starvation are extremely limited.
The average survival time for a normal-weight person practicing total fasting is two to three months.
Other reports, however, provide slightly different numbers.
When deprived ofboth food and water, they estimate that the body can survive for eight to 21 days.
However, it should only be done for hours, not days.
Before you begin fasting, ask your healthcare provider if it’s safe for you.
After 1 Day
Your body normally usesglucose, or sugar, as its main source of energy.
When you don’t eat, your glucose reserves are used up within one day.
After one day without food, your body releases a hormone calledglucagon.
This hormone tells your liver to make glucose.
This glucose is used mostly to feed your brain.
Your muscles use the fatty acids created during this process as their main source of fuel.
Fatty acids are also used to formketonesin the liver.
Ketones are another substance the body can use for energy.
These are released into the bloodstream.
When the brain uses them for fuel, it doesn’t need as much glucose.
Humans can survive without food because the liver can shift to ketone production.
After 7 Days
When the fatty acid reserves are gone, the body switches to protein.
This is what may ultimately lead to death.
Because a starving body lacks the resources to stay healthy, infection is another possible cause of death.
Before death, certain complications may occur.
The number of body systems affected increases as weight loss increases.
Summary
How long human beings can go without food is an open question.
The body works to fight starvation by producing glucose and breaking down fatty tissue.
In later stages, it breaks down muscle.
But without food, these efforts will fail and a person will ultimately die.
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