How Long Can You Go Without Food?

Estimates say as much as a couple of months, but this depends on several factors

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How long you can go without food varies, but it's estimated that one can live for 43 to 70 days before dying from starvation. In this time, the body survives by using fat stores for energy. When fat stores are depleted, it begins to break down muscle.

You can survive without food far longer than you can survive without water (which is only a few days).

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 starting weight play a role.

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

Timeline of What Happens When You Don't Eat

Your body is very resourceful. When you don't eat, 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, when.

Fasting or deliberately going without food for short periods of time can be a healthy way to lose weight or manage certain medical conditions. However, it should only be done for hours, not days. Before you begin fasting, make sure to ask your healthcare provider if it's safe for you. 

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, 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.

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. 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

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

Complications From Lack of Food

Verywell / Laura Porter

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:

Summary

The exact length of time human beings can survive 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 go 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.

A Word From Verywell

Most people who ask this question are simply curious about the answer.

But if you are purposefully restricting your food intake, your concern is very real. An eating disorder like anorexia or a very strict diet can have serious health consequences.

If this describes you, please seek medical help at once. You deserve the food your body needs to thrive and function.

Frequently Asked Questions

  • Will I lose muscle if I go without eating?

    Yes, but it takes time for your body to use muscle for energy. The body will exhaust all its sugar stores and fat reserves before it uses muscle. This can take a few days.

  • Can an obese person go without food longer than a normal-weight person?

    Possibly. There's some research that suggests obese people can fast for longer than lean people before experiencing side effects of starvation.

  • When will I start burning fat if I stop eating?

    Your body will turn to fat for fuel after about 12 hours. The process will speed up considerably after 16 to 24 hours without eating.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Elliot B, Mina M, Ferrier C. Complete and voluntary starvation of 50 days. Clin Med Insights Case Rep. 2016;9:67-70. doi:10.4137/CCRep.S39776

  2. Johns Hopkins Medicine. Intermittent fasting: What is it, and how does it work?

  3. Steinhauser ML, Olenchock BA, O’Keefe J, et al. The circulating metabolome of human starvation. JCI Insight. 2018;3(16):e121434. doi: 10.1172/jci.insight.121434

  4. Zarulli V, Barthold Jones JA, Oksuzyab A, Lindahl-Jacobsen R, Christensen K, Vaupel JW. Women live longer than men even during severe famines and epidemics. Proc Natl Acad Sci USA. 2018;115(4):E832-E840. doi:10.1073/pnas.1701535115

  5. Yaussy SL, DeWitte SN. Patterns of frailty in non-adults from medieval London. Int J Paleopathol. 2018;22:1-7. doi:10.1016/j.ijpp.2018.03.008

  6. Mehler P. Anorexia nervosa in adults and adolescents: Medical complications and their management.

  7. Michigan Health. Intermittent fasting: is it right for you?

Additional Reading

By Angela Morrow, RN
Angela Morrow, RN, BSN, CHPN, is a certified hospice and palliative care nurse.