Typically we apply the rule of 3. It is said that you can survive 30 days without food, three days without water and 3 minutes without breathing. That’s the theory, because in practice, many elements can vary these numbers.
The will certainly play a key role. A famous example is that of Bobby Sands, a member of the Irish Republican Army died in custody in 1981, after 66 days of hunger strike. Private food, the body will adapt.
In a first phase, from one to three days, the body will first exhaust its glucose reserves, water and salt. This often leads to a rapid and significant weight loss.
Then, during the second phase of up to two weeks, the energy is obtained by drawing on the reserves of fat and muscle. This will cause muscle wasting. The body is idling, lowering the heart rate and blood pressure.
In the third phase, the body will use the last available reserves, proteins, essential components of all our cells.
Survival limits are reached when 30 to 50% of the proteins are consumed or that the weight loss is equal to 50% of initial weight. But if you can live several weeks without eating, you can not hold much more than 3 days without drinking. Through sweating, breathing and evacuation of urine, we lose about 2 liters of water every day. If this loss is not compensated after 24 hours, the body is already dehydrated. In full sun, it can obviously go much faster.
One of the first signs is the color of urine becomes darker. Skin, tongue and mouth dry out, the blood thickens, blood pressure falls. The losses in minerals cause headaches, cramps, and consciousness disorders that can lead to coma. This is usually what happens when the body has lost over 15% of its volume of water.
A man in good health and will have to drink can resist long enough total lack of food. At 74 years, Mahatma Gandhi, the famous activist for the independence of India, spent 21 days in total young, just by drinking water. Other studies have highlighted the hunger strikes of up to 40 days.
Hunger and thirst
What is certain is that the body is able to adapt to the lack of food. He starts the “sleep”, saving energy on all fronts: lower heart rate, slowing all vital functions.
In cases of anorexia, a disease where individuals voluntarily deprive themselves of food, potentially fatal stage occurs when the body index falls around 12. (Remember that the BMI – body mass index – is obtained by dividing its weight by their height in meters squared. For a normal person it is between 18.5 and 24.9).
One might think that obese people who have more fat reserves, “take” longer than the others. This is true in the context of a normal calorie diet but below 400 calories per day, the body works so idle that the risk of cardiac arrest is as high.
Water is essential to the functioning of the body. No drink, it can hardly survive beyond a few days.
Water for our cells
While the man may take a relatively long time without eating, fluid deprivation is much more critical. Studies involving patients in persistent vegetative state noted a death occurring between 10 and 14 days without hydration. Under normal conditions, it can survive a few hours to three days depending on the outdoor temperature.
You should know that the water represents 70% of our weight, and it is indispensable to the functioning of cells and transport of nutrients in the body. If you do not drink enough, the lack of water in the blood causes increased salt levels. The cells are then released their intracellular water to dilute the salt and reduce its rates.
Conversely, if one drinks without eating, the salt in the blood is increasingly diluted. The cell, which must keep a salt content identical to that of blood, so lets water to dilute the intracellular salt. Sip of water, it will eventually burst.
In short, drink and food go together: it takes a water-cubic centimeter for calorie consumption. Dehydration initially affects the most fragile cells, neurons. The first symptoms are behavioral disorders, and loss of consciousness. Even minor dehydration can have serious consequences for water loss of 4%, the physical and mental performance fell by 40%.