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How long can you go without food?

The human body is a living organism that requires vitamins, nutrients, and minerals to function. Unfortunately, many people with eating disorders and other mental health concerns will deny their bodies these essential components for long periods of time, and this can have enormous consequences on cognitive, physical, and emotional well-being.

Some people may also fast for religious or ethical reasons, though these instances are generally controlled and temporary.

If you are wondering how long the body can go without food because you're thinking of fasting for reasons other than religious observances, you may want to speak to a mental health professional or, at the very least, a trusted friend or family member. These kinds of thoughts can be related to eating disorders and can lead to many health complications and concerns.

7
 minute read
Last updated on 
March 28, 2025
March 28, 2025
In this article

How long can someone survive without food?

The length of time a person can go without food depends on many factors, including age, biological gender, health, level of activity, and body fat. 

Since the topic can not be studied ethically, finding quality research on the subject is difficult. One study did find a patient was able to go without food for 382 days, which is widely considered to be the longest recorded fast by a human.1 However, the patient had regular medical supervision (and IV fluids) throughout this experience, and this case is thought to be extreme or an outlier.

Other studies have looked at the experiences of people on hunger strikes. They discussed different types of fasts and how long humans can endure them, including:2

  • Partial fasting: No solid food is consumed, but fluids, sugars, and nutrients are ingested
    • Estimated survival time: Indefinitely, but with severe impacts on health
  • Total fasting: Only fluids are consumed
    • Estimated survival time: 2-3 months
  • Dry fasting: No fluids nor solids are consumed
    • Estimated survival time: Approximately 1 week

Another analysis concluded that biological women may withstand starvation longer than biological men, as their bodies generally carry more body fat and use it differently.4

Regardless of these specifics, once the body is deprived of food for long enough, it sets off a cascade of biological changes that can be difficult to reverse and have severe impacts on all levels of health.

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Fasting and the human body: What happens to the body without food?

The body requires a combination of proteins, sugars, fat, fiber, minerals, vitamins, and calories to function properly. It usually obtains these through food, but if someone is fasting or starving, the body must look elsewhere for what it needs.

As the body shuffles through these different sources of fuel, metabolism also changes, which impacts the way the body uses energy. Essentially, everything downshifts, allowing the body to maintain essential functions with less fuel.

A lowered metabolic rate can be extremely problematic, especially for sustained periods of time, and potentially lead to major organ failure and other severe health complications.5

Starvation phase I: Glucose
Starvation phase II: Lipids
Starvation phase III: Amino acids

Symptoms of starvation

Symptoms of starvation can start out subtle but usually escalate rather quickly and can be especially visible once the body goes an extended period with very little food.

Some effects of starvation, long-term fasting, and/or severe hunger include:2,5,6,7

  • Muscle wasting
  • Hair loss
  • Social withdrawal
  • Weakened immune system
  • Impaired emotional functioning
  • Lowered sex drive
  • Gastrointestinal issues
  • Cold intolerance
  • Impaired brain function, including:
    • Alterations in consciousness
    • Delusions
    • Amnesia
    • Psychotic episodes
  • Renal (kidney) failure
  • Dizziness
  • Poor concentration
  • Disrupted sleep
  • Loss of body mass

Issues can quickly become severe and potentially life-threatening. And once someone has entered a phase of physical starvation, additional complications can arise from adding food back into their diet.

How to avoid refeeding syndrome after fasting

Refeeding syndrome is a dangerous and potentially deadly complication that occurs when someone who is starving or severely malnourished begins consuming more calories and nutrients.

Due to the metabolic changes that take place during starvation, consuming too many nutrients too quickly can cause major shifts within the body and lead to a dangerous imbalance of electrolytes, which can cause:8

  • Trouble breathing or respiratory failure
  • Double vision
  • Seizures
  • Coma
  • Cardiac arrest or other heart complications
  • Delirium
  • Hypothermia

Due to the potential dangers involved, working with a medical treatment team during this period is highly important. Doctors can monitor the levels of various nutrients and electrolytes and manage refeeding to ensure a patient's body is getting what it needs and is not becoming overwhelmed by too much too fast.

The greatest risk period for refeeding syndrome is within 5 days of starting the refeeding process.8 If you or a loved one has been starved or severely malnourished, it's essential to seek out appropriate medical care to start your refeeding journey.

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Finding help for an eating disorder

Intentional starvation is often a sign of an eating disorder or other mental health disturbance. If you or a loved one are intentionally limiting or eliminating food intake, it's crucial to seek out help. The effects of starvation can happen quickly, be severe, and be irreversible.

A number of treatments have been developed to address the very real mental and emotional issues that often work to drive these conditions. If starvation is serious enough, additional physical and nutritional treatment will likely be needed.

Speaking with a medical professional or licensed mental health practitioner can get the ball rolling. These professionals will likely be able to refer you to appropriate care centers or treatment programs. You can also explore the benefits of virtual eating disorder treatment through programs like Within.

Regardless of how you start your recovery journey, remember it's never too late. A healthier future is always possible.

Disclaimer about "overeating": Within Health hesitatingly uses the word "overeating" because it is the term currently associated with this condition in society, however, we believe it inherently overlooks the various psychological aspects of this condition which are often interconnected with internalized diet culture, and a restrictive mindset about food. For the remainder of this piece, we will therefore be putting "overeating" in quotations to recognize that the diagnosis itself pathologizes behavior that is potentially hardwired and adaptive to a restrictive mindset.

Disclaimer about weight loss drugs: Within does not endorse the use of any weight loss drug or behavior and seeks to provide education on the insidious nature of diet culture. We understand the complex nature of disordered eating and eating disorders and strongly encourage anyone engaging in these behaviors to reach out for help as soon as possible. No statement should be taken as healthcare advice. All healthcare decisions should be made with your individual healthcare provider.

Resources

  1. Stewart, W. K., Fleming, L. W. (1973). Features of a successful therapeutic fast of 382 days’ duration. Postgraduate Medicine Journal, 49(569), 203-9.
  2. Haselwarter, D., Wild, V., Kuehlmeyer, K. (2022). Providing health care in politically charged contexts: a qualitative study about experiences during a public collective hunger strike of asylum seekers in Germany. International Journal of Qualitative Studies on Health and Well-Being, 17(1), 2018770.
  3. Devlin, M. J. (2011). Why does starvation make bones fat? American Journal of Human Biology, 23(5), 577-585.
  4. Henry, C. J. K. (July 2008). The biology of human starvation: some new insights. Nutrition Bulletin, 26(3), 205-211.
  5. Singer, M., De Santis, V., Vitale, D., Jeffcoate, W. (2004). Multiorgan failure is an adaptive, endocrine-mediated, metabolic response to overwhelming systemic inflammation. Lancet, 364(9433), 545–548.
  6. Steinhauser, M. L., Olenchock, B. A., O'Keefe, J., Lun, M., Pierce, K. A., Lee, H., Pantano, L., Klibanski, A., Shulman, G. I., Clish, C. B., Fazeli, P. K. (2018). The circulating metabolome of human starvation. JCI Insight, 3(16), e121434.
  7. Calugi, S., Miniati, M., Milanese, C., Sartirana, M., El Ghoch, M., Dalle Grave, R. (2017). The Starvation Symptom Inventory: Development and Psychometric Properties. Nutrients, 9(9), 967.
  8. Refeeding Syndrome. (n.d.) Cleveland Clinic. Accessed November 2024.

FAQs

Can you get refeeding syndrome after fasting?

It depends. Refeeding syndrome is generally caused by severe malnutrition or prolonged starvation, which usually occurs only after longer periods of fasting or more extreme fasting measures, such as not having solid food and minimal fluids.

Intermittent fasting, juice cleanses, and other more common forms of fasting are generally safer and not likely to trigger refeeding syndrome. However, even these forms of limiting food intake should be done with care and caution.

Can you develop an eating disorder from not eating?

Eating disorders are complex mental health conditions and are generally caused by a number of interlocking mental, biological, and environmental factors. Choosing not to eat, especially when feeling hungry, is more likely a sign of an eating disorder rather than the cause of one. However, choosing not to eat for prolonged periods of time can contribute to the mental, emotional, and physical stress that works to develop or maintain eating disorders.

Can you get a headache from not eating?

Yes. Headaches can be caused by low blood sugar and other issues related to not eating.

Can you throw up from not eating?

It's possible. Not eating can make you feel nauseous and possibly throw up due to a build-up of stomach acid and other issues.

How long can you survive without food?

It's generally thought that the average adult can survive 2-3 months without food and just about a week without food or water.2

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