In general, it is likely that a person could survive between 1 and 2 months without food.

As many different factors influence the length of time that the body can last without food, this period will vary among individuals.

Scientists have not studied human starvation using traditional experiments due to ethical concerns. Data usually come from observational studies on hunger strikes and periods of famine.

In this article, learn more about the factors that affect how long a person can survive without food and water.

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Research into how long the average person can go without food remains limited.

A typical, well-nourished male weighing 70 kilograms (154 pounds) technically has enough calories stored to survive for between 1 and 3 months.

However, people who have voluntarily stopped eating to participate in hunger strikes have died after 45–61 days, which suggests that a person would be unlikely to survive for 3 months.

The body needs the nutrients in food to survive. It uses protein, carbohydrates, and fats, as well as vitamins and minerals, to renew cells and fuel vital bodily processes.

Without food, the body starts to use its own tissue as fuel, but it can only do this for so long.

Scientists are not sure exactly how long the average person can go without food. They have not studied starvation in traditional experiments because it would be unethical to ask a person not to eat for a prolonged period in order to examine the outcome.

The best indication that researchers have of how long people can survive comes from those who have been on hunger strike.

Many factors can affect how long a person can go without food. A person’s age, sex, body size, fitness, general health, and activity level all play a role.

The amount of liquid that the person drinks will also be significant. Experts believe that sipping water from early on in the period without food may prolong survival.

Food is the body’s fuel for its vital processes, all of which starvation affects.

Cardiovascular system

To compensate for the lack of food, the body breaks down its own tissue to use as fuel. This process may involve muscle tissue, including that of the heart.

The pulse and blood pressure drop because the heart does not have the fuel that it needs to pump blood around the body as effectively as normal. This inefficient pumping can lead to heart failure.

Gastrointestinal system

Food restriction interferes with how the stomach digests food and empties itself. It can lead to:

  • bloating
  • stomach pain
  • vomiting
  • nausea
  • fluctuations in blood sugar levels
  • bacterial infections

Long-term inadequate nutrition can also cause constipation because it weakens the muscles in the intestines. The weakened muscles may not have the strength to push digested food through the gut.

Another risk of starvation is pancreatitis, or inflammation of the pancreas, which causes pain, nausea, and vomiting.

Central nervous system

Starvation can affect the brain, which consumes up to one-fifth of a person’s energy. Depriving the brain of energy can result in difficulty concentrating and sleep issues.

Endocrine system

The endocrine system needs fat and cholesterol to make hormones, such as estrogen, testosterone, and thyroid hormones. Without them:

  • menstruation can become irregular or stop altogether
  • bones can weaken
  • metabolic rate can drop
  • core temperature can drop, leading to hypothermia

Symptoms may include dry skin, brittle hair, and hair loss. During periods of starvation, the body tries to keep warm by growing a downy layer of hair called lanugo.

As with food, it is hard to say exactly how long people can survive without water. While a fit adult might last a few days, a child whom a parent or caregiver has left in a hot car could dehydrate and die within hours.

The precise length of time for which a person could survive varies due to differences in individual body composition.

The body needs a continual supply of water to repair and maintain cells and carry out essential processes.

According to the Centers for Disease Control and Prevention (CDC), the symptoms of moderate dehydration are:

  • a dry mouth and tongue
  • restlessness and irritability
  • sunken eyes
  • feeling thirsty
  • urinating less

Severe dehydration can lead to:

  • lethargy
  • unconsciousness
  • a weak or absent pulse
  • a very dry mouth and tongue
  • low blood pressure
  • passing very little or no urine at all

Severe dehydration is life threatening. Learn more about how long humans can go without water in this article.

Starvation is not a good way to lose weight for many reasons, not least because it is very dangerous.

A person’s metabolic rate actually goes down when they are in starvation mode, meaning that they burn fewer calories. Poor nutrition due to starvation can lead to a multitude of health concerns.

It is very difficult to stick to a restrictive diet, and, as a result, these diets do not tend to be very effective.

A person can talk to a doctor about more sustainable ways to lose weight, if this is what they wish to do. An effective diet plan usually involves eating a nutritious diet and exercising regularly.

Learn about safe and effective ways to lose weight in this article.

The body needs the nutrients in food to survive. Without them, it will start to break down its own tissue to use as food. Starvation affects all of the body’s systems and processes.

It is difficult to determine how long someone can go without food, but experts believe that it is between 1 and 2 months.

Doctors strongly advise against starvation diets. Not only are they dangerous, but they are not sustainable. The best way to lose weight is by eating a healthful, balanced diet and exercising regularly.