How Long Can You Go Without Food?

As long as you have access to water, experts believe you can live up to two months without food.

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. Personal factors like your starting body weight play a role.

This article discusses the question of how long you can go without food. It also discusses some of the complications that can happen when you don't eat.

How Long You Can Go 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.

The following timeline of what happens to your body when you go without food is not exact, but it can give you an idea of what may happen and when.

After 1 Day

Your body normally uses glucose, 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 called glucagon. This hormone tells your liver to make glucose. This glucose is used mostly to feed your brain.

After 2 or 3 Days

After two or three days without food, your body starts to break down fatty tissue. Your muscles use the fatty acids created during this process as their main source of fuel.

Fatty acids are also used to form ketones in 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.

After 7 Days

When the fatty acid reserves are gone, the body switches to protein. Depending on how little fatty tissue you had, it may take only a few days to reach this point. By one week, however, the bodies of most starving people will be actively breaking down muscle in order to obtain protein.

After 14 Days

As the breakdown of muscle speeds up, the body begins to lose heart, kidney, and liver function. 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.

What Influences Survival Without Food

Sex, age, starting weight, and water consumption can all play into how long someone can go without food.

This is based on the limited research on this subject. For obvious ethical reasons, scientists cannot purposefully starve people in order to study this. Instead, many look at people who chose to starve themselves and were later evaluated by a doctor.

• Sex: Females survive longer than males. This is true even in famines.
• Age: Children are at higher risk of death during famines.
• Starting weight: Research indicates that lean people can usually tolerate a loss of up to 18% of their body mass and will become weak after 30 to 50 days without food. Death usually occurs between 43 and 70 days. By contrast, people who are obese may be able to tolerate more than 20% body mass loss. These timeframes are likely long for them as well.
  
• Water intake: Generally speaking, people can survive for longer without food if they drink plenty of water.

Complications of Going Without Food

Unless eating is resumed, starvation always leads to death. Before death, certain complications may occur. The number of body systems affected increases as weight loss increases.

Some of these complications include:

• Bone loss
• Muscle weakness and wasting
• Feeling cold
• Thinning or loss of hair
• Dry skin
• Constipation
• In females, loss of menstruation
• Fatigue, shortness of breath, and paleness from anemia, a lack of oxygen-carrying red blood cells

Summary

How long human beings can go without food is an open question. Estimates indicate that starving people become weak in 30 to 50 days and die in 43 to 70 days.

Individual factors including sex, age, starting weight, and water intake all play a role in how long someone can live without food.

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.