What happens when you lack food, water, and sleep

Some of us are fortunate enough to have made preparations for various disasters, and we can get our families along with our bug-out gear and hit the road before the brown stuff hits the fan.

However, since a family usually has more than two members, some folks will be deprived of various things, and most of them have no idea what would happen when they lack food, water, and even sleep. You can only ration your resources for so long, and with each passing day, your body will suffer. Let’s look at the science of scarcity and figure out what happens when you get thirsty, hungry, and tired.

We cannot predict the future

And that’s why most of us became preppers after seeing that only we are in control of our destiny. I’ve discussed the topic of keeping it real and pertinent on various occasions, and I’ve helped people figure out what they should prepare for based on their geographical position, social status, and financial situation.

However, I’ve also been telling folks for more than a decade now that they should never take things for granted, no matter how well-prepared they are or they think they are. Things can always go bad, and your plans may fail; therefore, it’s better to have a backup plan and figure out ways to become a little self-sufficient when the situation calls for it.

While many survival scenarios follow a somehow similar pattern, and they may be resolved in a day or two or perhaps in a week, what happens when that’s not the case? Sure, the storm will pass, and the power will be back on, but it doesn’t take a lot of imagination to realize that perhaps you might find yourself in a situation where your body will be pushed to its limit. 

The human body is a wonderful machine, and it can respond to hardship and be pushed to extremes. It’s true that if you’re a couch potato, your body may not adjust well to an environment where scarcity is ever-present compared to those that are active and in better shape. But even if you are fit and active, all our bodies are affected by the same three factors water, food and sleep.


The average human may survive for weeks without food, but when it comes to water, most of us won’t make it more than a few days without it. Water is the main and most critical component of all the metabolic processes in our bodies.

They say we are made mostly of water, and that’s somehow true. Scientists have established that the body of adults (regardless of gender) contains 55 to 60 percent water, while for the body of children and infants, the content of water present in their bodies ranges from 65 to 75 percent.

The amount of water we should drink varies greatly depending upon our weight, genetics, the activity we do, and nutritional state. One thing we know for sure is that most of us can tolerate up to 4 percent of total body water loss pretty well. If we lose 5 to 8 percent of body water, we will feel serious signs of dehydration, and once we reach 10 percent, our bodies will be greatly impaired. It was also estimated that a loss of body water of 15 to 25 percent is fatal for most humans.

Signs of dehydration

The initial symptoms of what is called mild dehydration are dizziness and fatigue, and many people will feel these symptoms during summer activities without giving them too much importance. If you don’t drink water, these symptoms will progress, and you will also start having headaches and lose your appetite.

As the dehydration process continues, you will notice a decrease in urine output, the fatigue worsens, and you will enter a state of confusion. One suggestion to check for signs of severe dehydration is to look at the fingernails since blueish-purple fingernails are usually the recognizable sign in this case. If water is not replenished, your body will suffer from a critical sodium imbalance, and you will experience seizures.

Dehydration may not seem like a serious problem in a safe environment because we can always replenish the water loss our bodies experience, but the situation changes considerably in a stressful environment.

In fact, it is believed that even losing a smaller percentage of body water, like 2 to 3 percent, can have disastrous outcomes when you’re struggling to survive. Dehydration is often considered to be a function of exertion, stress, and environment with serious cognitive impairment in a stressful environment.

The myth most people believe is that dehydration happens when you’re hot or when you live/work in a hot climate, but that’s just not true, and if you find yourself in a colder climate and you don’t drink enough water, dehydration will occur just as well.

Another thing worth mentioning that makes dehydration worse is diarrhea and vomiting, which you can imagine would be quite easy to experience in a stressful environment when you have to eat the same food over and over again or perhaps you have to forage for your food. Also, the consumption of excessively salty or sugary foods is another thing that should be avoided when you lack water.

Earn Your Food Independence NOW


Starvation is defined as a process in which an individual loses 30 percent of their normal body weight. If the loss of body weight increases to 40 percent, it almost always becomes fatal.

I’ve read on many occasions that the average human adult can survive between 30 to 45 days without food as long as plenty of drinking water is available. However, these statistics, I believe, can be very misleading since the lack of food not only affects the function of your body but can also affect the quality of your life. A miserable person has a lower chance of survival than one that is well-fed and doesn’t have to worry about his next meal.

You can go without food for a certain period of time, but your metabolic response to lack of nourishment will follow a few stages. In simple terms, it will switch from consuming carbohydrates from the diet to consuming fat from your metabolism.

This will lead to decreased insulin levels and, combined with the effects of stress hormones (cortisol and catecholamines), will bring your body to a stage of ketogenesis – the body produces ketone bodies that consume down fatty acids and ketogenic amino acids to provide energy to organs.

And when the supply of fatty acids and ketogenic amino acids runs dry, it will start a process known as protein catabolism when the body starts consuming critical proteins like muscle body mass. This starvation stage leads to organ failure and death.

The problem with starvation is that the process is unique to each individual, and it all depends on the body fat each of us have, even though the result of continuous starvation is the same for all of us. To put it simply, your body fat influences the time in which you will starve, and that’s why that “30 to 45 statistic” is misleading.

Experiencing the effects of lack of food is known in medical terms as inanition and irritability, hyperactivity, and impulsivity are described as the first noticeable symptoms. And contrary to popular belief, when you experience inanition, and your stomach starts to atrophy, the feeling of hunger begins to diminish.

When your body has trouble producing energy due to a lack of food, you will experience fatigue, lethargy, and a continuous state of apathy. As you can imagine, these effects are detrimental to one’s survival, especially if a person has to deal with an unknown environment. Even more, your body will become weaker and weaker, and you will fail to notice the feeling of thirst, which leads to dehydration.

If you are not able to acquire food, you will also experience avitaminosis (vitamin deficiencies) as starvation continues. This leads to a new set of problems like beriberi, pellagra, and scurvy.  

Starvation leads to a slowed reaction time, and one’s judgment is impaired. This can be disadvantageous to survival situations, and the entire process of decreased caloric intake is even harder to bear in a cold environment. In fact, you need much more food to maintain your body’s core temperature in a cold environment than in a warm one. You will also feel the effects of starvation much faster in such an environment.

Sleep deprivation

A lot of people have trouble sleeping in their own beds, let alone in the wilderness under the stars. Sleep is being studied intensively, and there is an entire medical discipline dedicated to it, but even so, we still don’t know much about it or understand the entire process well.

Being sleep deprived is not something you can really prepare or train for, and it happens to all of us. There are four stages of sleep that create a sleep cycle that can usually last between 90 and 110 minutes. Each of these four stages lasts between 5 and 15 minutes. They are as follows:

Stage 1

This is a light stage in which you might experience that falling sensation or sudden body twitch movements.

Stage 2

This is a deeper stage of sleep when your body calms down and your heart rate decreases. During this stage, there will also be a slight drop in body temperature.

Stage 3

This stage is known as non-REM (rapid eye movement) sleep, and it’s considered to be the most restorative stage for the immune system of the sleep cycle. It’s the stage in which most people have difficulty waking up. One thing to notice here is that this stage is responsible for sleepwalking, sleep talking, night terrors, and bed wetting in children.

Stage 4 or REM

It was established that REM sleep takes up almost a quart of the entire sleep cycle and is responsible for memory strengthening, and it is believed it also rejuvenates the body. It is the stage in which we dream, and waking up from this stage is quite easy compared to the non-REM one, although most people feel a somewhat amplified feeling of tiredness.

The initial signs of sleep deprivation are always noticeable to us and those around us. Yawning, fatigue, moodiness, and inability are always present. If sleep deprivation continues, you will start feeling depressed, and you will lack motivation even for the things you enjoy. You will start to forget things and have problems concentrating.

Sleep deprivation is often used as a military tactic to demoralize the enemy and increase stress. The more they go without sleep, the harder it will be for them to concentrate and do their job. Even more, after four days without sleep, a lot of people start to hallucinate, and you can imagine that this can lead to serious problems on the battlefield.

When your body lacks sleep, it will take it by force, sort of say, and it results in what’s known as episodes of micro-sleep. These are the episodes in which a person can experience the sudden onset of sleep, and they are responsible for many road accidents.

A lot of people don’t know that sleep deprivation can lead to death faster than food deprivation. Also, the record for the longest period of someone going without sleep and living after the ordeal is 11 days.

While every one of us is different, and we require various settings to sleep well, there are a few things we can do to increase our chances of sleeping better. For example, here are some things that work for most people:

Avoid drinking caffeinated beverages after lunch.

Avoid drinking anything after supper since you will feel the need to urinate during the night, and you will wake up.

If possible, include in your schedule a 60-90 minutes nap.

Try to work only night or day shifts if possible because switching between shifts will impact your sleep cycles.

Keep in mind that you will not be able to train to combat the effects of sleep deprivation. If you are sleep-deprived, you should expect periods of micro-sleep. Park your car in a safe space and take a nap if you have a long drive ahead.


Our bodies are remarkable machines, and we need to learn how they operate in order to take better care of them. The body requires water, food, and rest to function at full capacity, and if you lack any of these components, your performance will deteriorate regardless of the environment you find yourself in.

You can imagine that having to deal with a scenario when your survival is at stake, caring for your body and providing it with what it needs becomes critical. So take care of your body, and it will take care of you.

Written by

Bob Rodgers is an experienced prepper and he strives to teach people about emergency preparedness. He quit the corporate world and the rat race 6 years ago and now he dedicates all his time and effort to provide a self-sufficient life for his family. He loves the great outdoors and never misses a chance to go camping. For more preparedness related articles, you can visit him at Prepper’s Will

Latest comment
  • When I was young and stupid, I had a theory that the only reason people slept was due to lack of light. I stayed up for 3 days before my body shut down on me. It was miserable, a very hard experience To go through. The weird part was the longer I stayed up the harder it was to go to sleep. I don’t know if it’s related but I have had problems sleeping ever since. So don’t be stupid,