How long can you live without food?


We have moved onto the least important of the PLWF survival priorities, Food. This priority is not even a factor for short term survival; so how long can you live without food? Generally speaking the human body is able to survive for around 3-4 weeks without serious implications and to around 4-6 weeks before death. That being said you will struggle after 3 or 4 days to function at the higher levels you will be used to and will move a lot slower than normal… But might not even notice ๐Ÿ˜€

What exactly is food?

Food is made up of 3 main macronutrients โ€“ Fat, Protein and Carbohydrate. Added into this are other nutrients essential for health that include water, vitamins and minerals. All of these nutrients are found in plants and animals, sorry vegetarians, humans need meat AND plants to thrive. All of these are essential to continued survival; albeit not needed to be consumed every day as the body can store some but they will have a bearing on how long you can survive without food.

So what did the Flintstones do?

caveman finding foodThe human body has managed to evolve itself over millions of years into a survival machine. It has several mechanisms to ensure that regardless what food is, or more importantly isnโ€™t available, it will still function.

If we look back 20,000 years and focus on how humans used to eat we would see a stark difference to today. They would not have the local supermarket that they could visit on a regular basis (Spoiler alert – The Flintstones was not historically accurate). They didnโ€™t have farming, refrigeration or comfort foods like ice-cream or Frappuccino’s. It was a harsh way of life that meant early humans were only 1 meal away from being in survival mode.

Good old Fred and Barney had to get out into the wild and hunt for food whilst at the same time not get eaten by sabre tooth tigers and bears! Wilma and Betty would be found foraging for nuts, fruits and other plants with Bam Bam and Pebbles in tow close to their cave.

Vitamins and minerals

cod liver oilLet’s start with vitamins minerals and water. We have already discussed water and why it is essential for every cellular function so I will leave that there. Vitamins and minerals are the parts of food that are used to provide things like bones, help blood to fight infections, your brain to function, your nerves to fire etc. every bodily function requires some sort of vitamin or mineral for it to work in some capacity. In short, they are absolutely essential to life and will ultimately decide how long you can live without food as infection is normally the killer.

Carbohydrate

survival foodsSo now the evil carbohydrate and why it’s important. Your brain weighs around 2% of your total body weight but consumes 20% of the body’s total energy. Your brain CANNOT function without some form of energy, to keep things simple; this comes in the form of glucose. It can use something called ketones but thatโ€™s for another day.

Your body can get energy from carbohydrate quickly and efficiently and will always use carbohydrate as its primary source of energy when it’s available. To do this it breaks carbohydrate down so that the glucose part is usable by the body. Carbohydrate only really comes from plant matter in any useable quantity and not meat.

Fat

Eat fat to surviveFat is sourced primarily from meat and in smaller quantities from plants, mainly in the form of seeds. Modern diets, and bizarrely government guidelines, shun fat as being the greatest evil known to man. That is just silly and against what actually happens in nature and how the human body is designed to function (and has done so for 2.5m years).

Fat is the most energy dense form of natural energy that the body can use. Sugar (a carbohydrate) and protein have 4 kcal per gram; fat has 9 kcal per gram. To that end our caveman would always devour fat when he came across it, not cast it aside due to health concerns!

Stored body fat is converted back into glucose (or ketones) when the body is in survival mode. It is not an easy process to start off in the body and uses up essential energy being stored for a time of scarcity. Your fat reserves are your main energy source when you dont have food to eat and will decide how long you can live without food.

Protein

Snail for proteinLet’s look at meat (Protein source) which obviously comes from animals. Our caveman had to go out and hunt animals or fish in order to source essential nutrients such as protein, vitamins B-12 & D-3, Creatine and DHA which are not found in plants at all or in the case of protein in sufficient quantities.

These animals were difficult to hunt down and kill and required energy to be expended, but the pay offs were high due to the density of nutrients. Your body can use protein for energy but it does not like to do this as it is basically eating itself and breaking down muscles. This is bad and your body’s last ditch attempt at survival and to large extent decides when you are close to death how long you can live without food.

So what? How does this all affect survival?

This crash is because your blood glucose levels have spiked so quickly that your body overdoes the insulin which means not enough blood glucose; hence the lethargy. Glucose is burnt by the body very quickly, especially when the body is used to burning refined carbohydrate such as sugar (which the body has no biological function that requires you to consume it) And so the yo-yoing goes on. So where does that glucose go? Well, to keep things simple, your body stores it as fat; this is an evolutionary adaption for when food is scarce. If you have no food to eat the body will use its stored energy, which is stored body fat.

The clever amongst you will have realised that the modern diet of high carbs is bad for dieting and staying lean, but that is another argument for another day. High fat diets with low carb are absolutely essential for survival in the wilderness despite what Weight Watchers will tell you. It is simply to do with effort vs reward; finding sufficient carbohydrate to live on in the wild year round is very difficult. Meat has a high payoff vs effort due to the fat and nutrient dense organs that can be consumed and the fact that your body can store this fat and lengthen how long you can live without food.

sugar burning

Burning glucose

Blah blah blah… I still don’t get what this means?

Let me use a simple list of the order of preference that the body will use macronutrients.

1st – Carbohydrate
2nd – Fat
3rd – Protein

This means that during times of plenty the body will burn carbohydrate as an easy and ready main source of energy. When there is an excess it is stored for a less plentiful time, such as winter. When it comes to winter and there is little food, the body will then use fat as its main energy source. This is now eating into valuable reserves so the body will only do this when it has no carbohydrate energy source. Finally if your fat supply has been used and you have absolutely nothing else your body starts to break down protein (your own tissues) and use that. This is a final attempt at surviving and is normally the start of the onset of death and as I said earlier will dictate how long you can live without food being consumed.

So how long can you live without food?

Still with me? Good. The bottom line is here that most developed countries populations have ample fat stores to see them through quite a long period of no food. A pound of fat has 3,500 kcals; an adult male requires around 2,500 kcals per day if lightly active, a female around 2,000 kcals.
This means that even if you are lean with 6 pack abs (around 10% body fat for a man and 15 – 20% for a woman) you will still have around 20 pounds of fat = 70,000 kcals = 28 days of using 2,500 kcals or 56 days if you are carrying 40 pounds of fat. Unfortunately it’s not quite as simple as that as 30 – 40 days is around the longest you can live withoutย food for various other reasons such as lack of vitamins, infection and organ damage etc.

To summarise everything in a nutshell – You can live for a long time without food so don’t stress too much if you don’t have it. You tummy will make some outrageous noises, but dry your eyes princess, you will be fine without food providing you have no underlying health issues.

I hope that that makes sense and you can see that food is way down the list of priorities and at the end of your PLWF list when you are in a survival situation. Before you go though, please have a look at my other articles as they have some great information in them.

Please share this post and comment below as I am always interested in what you have to say; good or bad.

Until next time

Dave

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31 comments

  • Hi Dave.

    This website looks great. I like the way you are able to simplify a relative confuseing subject. The flintstone stuff makes it more funny๐Ÿ˜
    I did not know that the body react this way when it has no carbohydrate source.
    Very informativ and userfriendly website!

    What do you think of Spirulina as a survival food supply?
    Is this stuff worth the money?

    Thanks

    Kenneth
    ownmindsurvive.com

    • Thanks Kenneth, I always love feedback.

      To answer you questions about Spirulina, well I hate to sound like a politician but it depends. If you are on about wild seaweed then it is probably quite good in terms of the benefits vs energy expended to source it. If you are on about processed Spirulina then I am afraid it is a difficult one to answer as any processing destroys nutrients in any food. I am against processing food if possible for that reason and Spirulina seems to be one of those new fad ‘superfoods’ that an en vogue just now.

      I suppose the easiest answer it to give you the pros and cons of wild seaweed as I dont think the tablets will be great for you.

      Pro

      Very nutritious
      Likely to be fairly abundant (if wild seaweed)
      A good ratio of Omega 3:Omega 6 oils (2:3)
      Fairly well balanced in macro nutrients
      Good source of vitamins and minerals

      Cons

      Will require some kind of prep before eating (steaming or boiling)
      You could overdo it on some vitamins if using it exclusively for more than a few days
      You make have to get wet to source it = expending valuable energy
      Easy to confuse edible and inedible seaweed if you are not familiar

      Try this website for the nutritional information for Spirulina

      I hope that helps.

  • LakanDula

    Hmm….I prefer to have a food supply, or even more importantly know how to attain, hunt and gather food like our ancient forefathers did. But damn..I never knew our bodies could survive long without food, given that we don’t have health issues, which unfortunately forms am inority of the world population, most of us have health issues we’re not even aware of because they can seem to subtle at times.

    • Dave

      The body is a wonderful piece of bio-engineering that has evolved over millions of years despite numerous ice ages, droughts, disease outbreaks and predators! It is not surprising really that is can do SO much with so little when you think of what it has been through to get to the modern day.

      As for health issues, man dont get me started! The countries with the greatest healthcare systems in the world have the greatest chronic and lifestyle illnesses such as heart disease, strokes, diabetes, hypertension, brittle bones, dementia, the list goes on. not many people in the rain forest die of heart attacks or end up with dementia. Thats another post for another day though ๐Ÿ™‚

  • Ian

    Interesting. Though I have read another study that concluded that our Paleolithic ancestors actually were not at the point of starvation all the time, since they supplemented their hunting with gathering of roots, berries, nuts, etc. which are often also the source of protein. They actually had more leisure time for social bonding within the group which was also essential for survival.

    That being said, I do agree with your message of the hardiness of the human race when it comes to survival without food. At times when our Paleolithic ancestors did face a crisis, because of natural disaster, conflict with other groups, and climate change, then they would have needed to go without. Sometimes hunters would come back empty handed, but I imagine that they’d still have roots, nuts, berries, and jerky on hand.

    Sorry for the long reply, this subject is a fascinating one to me.

    Good post by the way, very thought provoking. ๐Ÿ™‚

    • Dave

      Ian,

      This is one of those arguments that could go on for a long time as its difficult to prove conclusively exactly what our ancestors did or didn’t do. That being said one thing that is not difficult to prove is milions of years of evolution which has gotten us to where we are today. Our bodies are adapted to store excess carbohydrate as fat, which was an adaption that help see man through the winter.

      It is no coincidence that most fruits are ripe towards the beginning of Autumn (Fall) time, this allowed ancient man to gorge for the few weeks that the fruit was edible and would see the benefits of it by converting it to fat. This would then see then through the harsh winters in the form of a fuel source and insulation.

      This would imply that ancient man did not in fact have an abundance of food and although probably wasn’t on the point of starvation, they had very little flex in their diet. I doubt there were many cavenmen suffering from being overweight ๐Ÿ™‚

      I love this subject and could debate for hours on, lol. What are your thoughts on this?

  • Sammi

    You’ve really made a complicated subject easy to understand. However, understanding it and putting it in to practice is quite often 2 separate things!

    You’ve enlightened me on one thing in particular, I thought fat was burned in the body first over carbs but obviously not! Recently meat has taken another hit in the UK media – about rare meat being a probable cause of cancer – there is always some type of meat, protein or dairy being blackened in the media!

    You’ve got a great site and really informative article here!

    Sammi

    • Dave

      Sammi,

      Thanks for your kind words. I read the article about rare meat being bad for you; to be honest, I work on theory that if it is being reported in the newspapers then it is probably nonsense! Just thinking about it logically should tell you all you need to know, meat, the only real source of protein in the human diet causes cancer?! That must surely mean that all vegans will never get cancer… Or B!

      With regards to fat burning over carbs, it is a common misconception and hence why 99% of diets dont work as they exclude fat and increase carb intake ๐Ÿ™‚

  • Ron Alderman

    Hi Dave,

    You have a great blog here. The information is important and not something that most poeple consider anymore. Most people just don’t think they will every be without food so they don’t know what might happen if they lose access to the grocery store.

    I enjoyed your entertaining presentation of the information while at the same time clearly explaining what your body needs whey it needs it and when.

    Thanks for the information and for a site to follow up with as you have new information available.

    • Dave

      Thanks Ron,

      One of the first world problems that we have is everything is convenient and nobody knows how to do anything for themselves anymore. Oh well come doomsday I will be okay ๐Ÿ™‚

  • G.C.Horton

    As a former member of Special Forces and the 1st Ranger Battalion, I went through a lot of survival training and occasionally taught it too.

    Your point that we can survive quite a while without food is absolutely true. In my experience, the body becomes more efficient at burning fat when there is less of it on the body. In Ranger School, the skinny guys did not lose as much weight as the chunky guys.

    A problem we had in survival training that I never see mentioned on survival sites is the effect of caffeine and nicotine withdrawal. This was a real problem for the first few days without food.

    As guys withdrew from caffeine and nicotine they became lethargic and moody by the afternoon of the first day. In some cases they were plagued with severe, debilitating headaches and confused thinking. This made them and everyone dependent on them vulnerable.

    • Dave

      G.C. you bring up some really good points which I will address now –

      Firstly, respect for getting through Ranger School!

      Skinny guys burning fat more efficiently – I totally understand why it can look like that, however the body can only burn at a set rate and its all to do with calories expended. The bigger guys are lugging around a bit more weight so will burn more calories although we are only talking about a couple of hundred extra over the course of a tough day. Also, the bigger guys will have a more recognisable shape (round) that will show shape change easier when they lose weight. Skinny guys who are slim already wont show that dramatic shape change; although their shape will change a bit. Does that make sense?

      Caffeine & Nicotine – This is something which I suffered from several times in the past before giving up caffeine for good in the summer of 2007. I had a bad sinus infection whilst deployed to a desert environment, the pain got a lot 30 mins after a large cup of coffee so I stopped drinking it in order to get some respite. 2 days later the withdrawal kicked in, and I mean really kicked in; I had horrendous headaches, shaking, lethargy and worst of all I had no concentration whatsoever. These symptoms lasted for about 3 – 4 days at the extreme levels and after another 4 or 5 days disappeared completely.

      After that I realised how the beverage industry is a complete scam and they are basically peddling drugs to get you addicted, lol. I haven’t touched a drop of caffeine since (well apart from when the guys though it funny to give me a ‘full fat’ coffee!)

      So in answer to your point, Caffeine and I assume Nicotine (I am a non-smoker) withdrawal are real big issues for the start of a survival situation and could seriously jeapordise your chances of survival.

      I hope that answers some of your points?

      RLTW!

  • Stephanie

    Hi Dave:

    Interesting to know just how long our bodies can go without food. I never would have guessed that if whatever reason we run out of food or a natural disaster strikes that the human body is capable of going a rather long time without food minus any serious health concerns like you said. For instance, I am sure it is different if you are diabetic.

    The Flintstones was one of my favorite shows when I was young and enjoyed the analogy. What was interesting to me is that our early forefathers were much like big cats we hear about in the wild. They hunt and eat prey so they can keep themselves and their cubs alive. It comes down to just how similar all of God’s creatures are.

    Thank you for the enjoyable read, Have a great day!

    • Dave

      Stephanie if there is one thing I have came to realiseover the years its how magic and amazing the human body is. The ability to survive for so long without food is just one aspect.

      Thanks for your comments and please come back soon.

  • Anthony

    Hey Dave how’s it going?

    This was a pretty sweet read and I found my self actually reading the entire article which doesn’t happen a lot for me lately. I was pretty fascinated to learn about how long I could last without real food. I figured maybe 14 days tops haha. If I ever get lost out in the woods while hiking I will make it a point not to panic about starvation and conserve energy. Very interesting thank you.

    -Anthony

    • Dave

      My pleasure Anthony, its good to know I managed to keep you attention, please have a read of my other articles as they are just as informative.

  • Mike

    In the Bible, we read of many people who went without food for very long periods of time. Jesus fasted often, at least once for forty days. Food is not the most critical thing for survival. Air and water are far more important in the short term. If seriously injured, medical attention is also critical.

  • But what about someone like me who is super skinny, I only weigh a 115 pounds with a height of 5″6, would I have enough fat to last long?
    I also get shaky and feel horrible if I skip a meal, would this go away if I just didn’t eat to stop it? I’ve not been diagnosed with anything that would cause this. Yet I have been to the doctors for this and other health problems, but they keep saying I’m healthy.

    • Melissa,

      Everyone can survive for varying lengths of time for a multitude of factors. Even although you are skinny you are probably carrying more body fat as a percentage of weight than a man. So even if you have the first signs of abs showing through you will still have around 20% body fat, sorry. Women just need more fat in their body than men due to breasts containing a lot of fat as well as the reproductive organs. You can see pictures for each body fat percentage. here

      As for you feeling shaky and horrible, you are suffering from hypoglycemia (low blood sugar) which is caused by a diet high in carbs and low in fat. Depending what you believe with regards to carbs, protein and fat ratios required for health. Its funny but the US government guidlines for fattening cattle up have exact;y the same ratios of carbs, protein and fat as the portion sizes meant to be healthy for humans. Is it any wonder the USA is the fattest and most sickly nation on the planet?

      I have never been healthier, leaner or fitter since adopting a high fat and low carb diet. I used to be a carb monster and had horrendous lows in the afternoon where I would struggle to stay awake, now I have a constant high energy throughout the day. If this interests you than I would recommend the following book and website, the website is amazing with an abundance of great articles and doesn’t cost a penny,and the my copy of the book is well thumbed. Excuse the pun, but its food for thought…

  • Candace

    You have a great site. Conversations about survival come up pretty frequently with some of my friends. I always thought food would be near the top of the list of things needed in a survival situation. It’s good to know we can survive so long without it. Also I think people in our modern day society grossly misunderstand our need for fats. I really liked what you had to say about it. This post reminded me of that book about Christopher McCandless. Have you read that? He starved to death, but his situation was pretty extreme and some would say self-inflicted. This post is full of great information. Thanks for the read!
    ~Candace

    • Dave

      A lot of people don’t realise this about food, that is why I started my website. I haven’t read the book you spoke about, it sounds like a survival fail though, lol.

      Agree with fats being misunderstood, fats are SO good for you yet 95% of people shun them! Crazy.

      Thanks for reading my post, please have a look at my others as well. I may be biased, but they are all pretty good ๐Ÿ™‚

  • Jacob

    Hi,
    Informative post there. So do you meant that carbohydrates is the most important source of energy in all?
    I have seen articles that a man can live weeks without food and your articles exactly describes it.
    A question for you: why do humans need water more than food?
    Jacob

    • Dave

      I suppose I have to give a politicians answer, it depends.

      There is no macronutrient that is best in all survival situations, it depends on your environment, your own health and fat reserves and what is available to eat.

      As a guide, food is not massively important for the first week or so for most healthy individuals. After that then anything you eat will help you, however carbs and fat are probably best as protein requires more water to process and is the last thing your body will metabolise for energy… However if you only have protein then get eating, it’s better than nothing. Carbs are the easiest to access energy source for your body to breakdown and access.

      On the flip side, if you are in the middle of the desert then water is your number 1 priority as you can be dead in 48 hrs!

      As to why the body needs water more than food, it’s actually quite a simple reason, almost every biological function in the body requires water to function correctly. no water, no functioning of the body which ultimately results in death…

  • Netta

    Hey Dave:

    Thanks for the thorough explanation about basics of how the human body uses food (and how long it can survive without sustenance). Just knowing that one can go for as long as a month-and-a-half without major chow-downs is somehow liberating.

    (I really would prefer not to go there, of course, but if I had to, at least I know that I’ve got some time before things get critical!)

    In all the modern hoopla about this super-food or that and all the fancy diets that seem to spring up and then proceed to morph into the surreal , it seems to me that we have somehow lost sight of the reality that we humans are basically carnivores and in conditions that are primitive, we will tend to revert to that…or die.

    • Dave

      Agreed,I could never be a vegetarian, if we weren’t meant to eat meat, why does it taste so good ๐Ÿ™‚

  • Wil

    Haha I’ve always thought this for myself, how long it may take me too keel over after I haven’t eaten for a while. haha i feel like I’d die out much sooner than 3-4 weeks. I start trippin out after like 5 to 6 hours lmao. My body is too big, it chugs. Haha need to shed some unneeded poundage so the struggle is not so real.

    • Dave

      Haha, another way to look at it, you have plenty of reserves to live off of ๐Ÿ™‚

      In all seriousness though, the ideal is probably somewhere in the middle as it is lack of vitamins, minerals and the failure of body processes that kills you, not normally lack of fat reserves. A pound of fat equates to 3,500 calories so most people have plenty in reserve. A 170 lb man with 5% body fat (which is insanely lean, think professional body builders in competitions) would have around 15 days of fat supplies if they needed 2,000 calories a day or around 25 -30days in die or survive mode.

  • Koda

    Very informative post! It really makes ya think. We are these human machines that run off of macronutrients and water. Without carbs fats and proteins we’d be in a load of trouble! I forget how fragile the human system can be.

    Cool survival facts tho. Always good to know.
    Hopefully I’ll never find out how long I can go without food ๐Ÿ˜€ Thanks for the post!

    • Dave

      The human body is fragile but also extremely resilient when it comes to survival, it just wants to survive at all costs. Evolution is a clever process ๐Ÿ™‚

  • Rob S.

    I’m always interested in anything about survival. I wasn’t aware of just how long you could live without food. I know you can only last maybe a few days without water. With food, you need all the minerals and vitamins and everything your body needs to function. It’s interesting how your body uses these macronutrients in a specific order. It just pays to eat healthy and never get yourself in a situation where you may be lost and stranded without food and water.

    • Dave

      The body is a wonderful thing but it does require nutrients and energy which has to come from somewhere ๐Ÿ™‚

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