How long can you survive without oxygen, water or food?

A general rule of thumb about how long you can survive without the basic elements for lifeconsidering oxygen, food and water, is the rule of three:

  • 3 weeks without food
  • 3 days without water
  • 3 minutes without air or oxygen

But obviously, this is a rule extremely vague and without much probability of being successful in any specific case. The survival time due to the lack of these substances is affected by many factors, for example, age, energy reserves, state of health, level of effort, environmental temperature and humidity, and a long etcetera.

Anyway and in any case, don't expect to survive long without them. Dying from lack of food is the slowest, followed by dying without water and finally dying from lack of oxygen.

starve to death

The medical term used for death from lack of nutrients is starvation, a malnutrition and extreme caloric deficiency. Starvation produces organ damage that can become irreversible and lead to death due to multi-organ failure.

The time that a person can survive without eating food depends on factors such as health status, age and previous energy reserves in the body. Some studies estimate that, on average, a person can survive between 8 and 12 weeks without eatingalthough there are documented cases in which 25 weeks have been reached.

People exposed to starvation become less sensitive to the sensation of thirst, so death often occurs from dehydration rather than lack of nutrients. It also weakens the immune system and makes a person more likely to contract a severe infection that can lead to death.

If the person survives long enough, the body begins to use protein as a source of energy. These proteins are obtained primarily from muscles, including the heart, and a common cause of death is heart failure caused by tissue damage.

die from dehydration

Water is one of the essential molecules for life and that the body needs to replenish with high frequency. Depending on some factors, such as age or weight, the 50-65% of the human body is made up of water, up to 75-80% at birth. Water is critical for maintaining vital functions such as digesting food or forming the fluids that transport and eliminate substances throughout the body.

Dehydration gradually produces a series of symptoms. When 2% of body weight is lost in water we start to feel thirsty, although signs of severe dehydration usually appear when approximately 10% is lost.

In this situation, dry skin, fatigue, lightheadedness, confusion, and rapid pulse rate and respiration rate appear. As water is lost, the body redistributes what remains to vital organs.

The tongue is usually inflamed while the mouth and the entire digestive and respiratory tract remain dry, causing an irritative cough. Despite the lack of fluid, vomiting is a very common symptom.

Shrinkage of brain tissue from dehydration causes a Strong headache, worsened when the meninges are torn and separated from the skull bones. Lightheadedness and confusion may be accompanied by hallucinations.

One of the first organs to fail and stop working are the kidneys. Waste products accumulate and reduce blood filtering. occurs a toxic waterfall which affects other organs. In the last stage, consciousness is lost, convulsions may appear, and finally death occurs. death from liver, kidney, or heart failure.

The time from when you stop drinking water until you die can be two or three days, but there are cases in which it has lasted a week or more. Factors such as health, weight, physical effort or environmental temperature and humidity play a fundamental role in this time.

die from anoxia

How long you can survive without air, or more precisely without oxygen (anoxia), like the previous cases, depends on several factors. If you are looking at air or another gas mixture and not just oxygen, the issue can be even more complicated.

For example, if the same air is breathed constantly, exhaling and inhaling from the same air, the fatal outcome may be more rapid due to the excessive increase in the concentration of carbon dioxide to toxic levels.

One of the organs most sensitive to lack of oxygen is the brain, which dies due to lack of energy to maintain brain activity. Remember that oxygen is necessary to burn glucose, molecules that brain cells use as their exclusive energy source. The brain death due to anoxia can be prolonged with low temperaturessince the metabolic rate becomes lower.

When cardiac arrest occurs, brain death occurs in a similar way. The blood stops flowing and no oxygen reaches the brain. If the cardiopulmonary resuscitation achieved within six minutes, the brain may survive without severe permanent damage.

If the lack of oxygen occurs in another way, for example by drowning, brain cells begin to die earlier than from cardiac arrest, approximately from 1 minute. The person loses consciousness after 30 – 180 seconds and after 3 minutes it is very likely that irreversible damage has occurred. Between 5 and 10 minutes brain death occurssome cases in low temperature conditions can survive up to 15 minutes.

Go up