Food
The most common cause for accidents in the wilderness is low blood sugar level
combined with dehydration. Technically
you can survive for 44 days without food, which the incredibly inspiring
illusionist David Blaine proved in 2003 (he's also got a journal here).
However, in a wilderness survival situation you would most likely dispense with
more energy than you normally would - and you would probably not know about it
because of increased secretion of adrenaline and activation of our survival
instinct which causes us to go far beyond total glucose (energy) depletion
(we do however lose consciousness if we stretch too far because muscles steal
glucose from the brain). In this extreme situation the initial phase is the most
important. You may be able to survive for weeks without food, it all depends on
how well you prepare for it. In practice you might be in quite bad shape after
just a few days because of all the work you need to do (for example building and
improving the shelter, collecting fire wood, carrying water, etc.).
But why go without eating when there's food in the wilderness? Fish and wild
animals may be the first you think of, but neither are priority one. Something
about nutrition...
Energy expenditure
At rest an adult expends about 1 kcal of energy per minute (60 kcal per hour,
1440 kcal per day). When walking or during a light hike an adule expends about 5
kcal per minute (300 kcal per hour, 7200 kcal per 24 hours). During a usual
summer hike with a light full pack (not ultra light) an adult expends about 7
kcal per minute (420 kcal per hour, 2100 kcal per 5-6 hours) when walking. So if
a hiker walks for 5 hours effectively per day, resting and doing typical camp
life activities, then rests (i.e. sleeps) that hiker could expend about 4000
kcal per day. If that hiker doesn't want to loose weight s/he would have to eat
at least 4000 kcal worth of food per day. All these figures are of course much
lower during starvation or when rationing food. When living on a low calorie
diet (especielly very low carbohydrate contents) the body can lower the energy
expenditure to as much as 30% (42 kcal per hour during rest, 210 kcal per hour
during a normal hike, but the hiker would probably not be able to keep the same
pace as earlier so the energy expenditure would be less). What shall we eat
then...
Carbohydrates
The most important ingredients in your diet are carbohydrates (60%), fat (30%)
and protein (10%). You need far more carbohydrates than fat and protein, not
only because the body can only store about 500 grams of carbohydrates (400 grams
in the muscles and 100 grams in the liver) but also because it's what the brain
lives off (glucose, commonly called blood sugar) and without it your
ability to think clearly is gone. If you eat more carbohydrates than you need it
will be converted into fat and stored in the body. About 20% of a normal
person's body weight consists of fat. This fat reserve lasts for about 2 weeks
(normal BMI 20-24 male) while the carbohydrate reserve only lasts for about 24
hours. Carbohydrate (or rather the end product, glucose) is important since
consuming even a very small amount will keep the body from using protein stored
in the muscles as fuel (gluconeogenesis, the process of turning something other
than carbohyrate into glucose). If the body converts protein (some amino acids
at least) into glucose (energy) one will eventually become weak, especially in
muscles not used, i.e if you hike without food your legs may feel fine
(or at least almost fine) but trying to lift something later on (with your arms)
may feel extra tough (this primarily depends on that there's no glucose stored
in or pumped into muscles not used - this is derived from personal
experience, I know some would disagree and say it's all because of
gluconeogenesis, but that doesn't explain why the legs feel fine). Consuming a
small amount of carbohydrates will keep the deterioration of muscle mass much
lower (I personally lived on 80g carbohydrates for 5 days without feeling weak
during or after the entire experiment).
Carbohydrates are found in plants and to make things more complicated, there are
several carbohydrates such as starch, sugar, inulin, lichenin, maltose and
cellulose - all depending on which plant and which part of the plant.
Carbohydrates are divided into two basic types - complex and simple. Simple
carbohydrates are 1-3 units of sugar linked together in single molecules.
Complex carbohydrates are several hundred thousand units of sugar linked
together in single molecules. Complex carbohydrates doesn't taste as sweet as
simple (i.e. sugar) and takes longer to digest. Simple carbohydrates is the
easiest source of energy for the body to use. Break-down of sugar even starts as
early as in the mouth using an enzyme called invertas. It then continues down to
the stomach which is passes relatively quickly (since sugar is easily digested)
and eventually enters the small intestine where the real break down usually
occurs. When the food has been "sliced" in extremely small quantities
(molecules) it passes through the wall of the small intestine straight into the
bloodstream where it can be used by various organs (e.g. the brain) and muscles
for energy. With sugar, this process usually takes 10-15 minutes on an empty
stomach. When sugar, starch (even fat and protein) are consumed in more than
survival quantities they are stored in the liver (in liver cells) and in
the muscles (in muscle cells) in various forms (this processes is mainly
controlled by the amount of insulin in the blood). Sugar is "faster"
while starch (complex carbohydrate) is "slower" and provides an even
amount of energy over a period of time (here GI - Glycemic Index comes in;
faster carbohydrates have a high GI while slower carbohydrates have a lower GI).
Starch is by far the best (better than sugar) and cellulose is the worst since
humans can not break it down into glucose (we lack cellulase - an enzyme
required to break it down into glucose).
Protein and fat
Fish is your best source for protein, fat and B vitamins since it's easier to
catch than most wild animals (provided you find a lake in the forest). Don't
exclusively focus on wild animals, I'll give you four reasons why you shouldn't:
1) a diet consisting of only meat make you sick and tired after a few days, 2)
most wild mammals have very little fat on them, 3) the brain, the red blood
cells and the kidneys can only function with one fuel - glucose (carbohydrates)
and without it your ability to make right decisions is degraded (proteins and
fat are however converted into glucose, but the process is slow and
energy-consuming), and 4) catching wild game is difficult and exhausting work -
especially in a survival situation - which means you would need carbohydrates in
order to hunt effectively anyway.
Vitamins
Although you can go weeks without vitamins C and B it's recommended to consume
them daily. Both vitamins C and B are water soluble, they can not be
stored in the body for long periods of time like other fat soluble
vitamins.
Vitamin (vital amine) C (ascorbic acid) is essential in the production of
collagen which in turn is essential for binding cells and tissue together. When
tissue is wounded collagen acts like a glue and binds the damaged tissue
together forming a scar. It's important since it keeps tissue healthy (and
prevents/treats scurvy).
Vitamin B is actually a group of 8 vitamins - B1 thiamine, B2 riboflavin, B3
niacin, B6 pyridoxine, B9 folic acid, B12 cyanocobalamin, pantothenic acid and
biotin. These acids (vitamins are acids) are essential for the body to be able
to break down carbohydrates into glucose and to break down fat and proteins.
Long-term vitamin B deficiency results in degraded metabolism as the body can
not efficiently break down carbohydrates, such as starch, into glucose (energy)
and general weakening of the body.
Pine or spruce needles contain vitamin C year round and is available any time
of the year throughout the arctic/sub-arctic forest region. Boiling tea from
two hands full of needles in 0.5 liters of water will contain up to 25 mg of
vitamin C and about 20 kcal worth of sugar (depending on season).
Folic acid (folate, a B vitamin) is found in green leaves (folia = leaf
in latin), berries, nuts and seeds. Acorns and Nettles are important vegetable
sources for B vitamins. When you boil nettles, make sure to also drink the
water since B vitamins are water soluble. Dandelion leaves, fresh green seeds
and leaves from Common Plantail (Plantago major) are other examples.
Large amounts of other B vitamins along with iron can be found in the liver of
animals, but fish is also an excellent source.
Minimum calorific intake in a survival situation
Author, survival researcher and instructor Stefan Källman, among others,
suggest a minimum calorific intake of 500 kcal worth of carbohydrates
(about 125 grams of sugar which is 99% carbohydrate) per day. Fat gives you
more than twice the energy compared to carbohydrates, but should not be
included in this calculation. An adult male need about 1500-2000 kcal of pure
carbohydrates per day (60% out of 2500-3000 kcal total daily need) for typical
office work (an adult female need slightly less). On a light hike an adult need
about 3000-4000 kcal per day, 60% of that should be carbohydrates (about
1800-2500 kcal worth).
During 5 days in June 2005 I lived off about 320 kcal (80g, 1340 kJ)
carbohydrates per day and was in perfect physical and mental condition the
whole time. I didn't move very much in the terrain, maybe 2-3 km per day on
average and the climate was nice and warm (between 15°C and 25°C).
Under these circumstances 320 kcal was enough and proved to me that one can
sustain him- or herself perfectly well on even less than 500 kcal of
carbohydrates per day (depending on the climate and physical activity). I know,
from a physiological theoretical point of view, that the body entered
gluconeogenesis, but proved that it was not enough to make my muscles feel
weak.
You should be able to live for 2 weeks on 500 kcal (about 2000 kJ) worth of
carbohydrates per day and still be clear in your head any time of the year -
however - your fat reserve is most likely gone after this long, which means
that the body can not use fat as energy and will eventually (after 2-3 weeks)
enter the final stage of starvation (before death), the 2nd gluconeogenesis. If
your survival situation lasts more than a few days you have to start thinking
about how to get fat and protein. Because of big changes in the metabolism, 1
of 20 puke on the second day even when eating. If you do, try to at least drink
a lot of water and continue on your diet.
Measuring energy in food
Kcal (kilo calories) and Joule are two units used to measure the energy value
of food. 1 kcal is about 4186 Joule, 500 kcal is about 2 MJ (Mega Joule) or
2000 kJ (kilo Joule). Good survival literature should have charts on how much
carbohydrate different plants contain in percent, what kind of carbohydrate
(sugar, starch, inulin, lichenin, etc.) and how much energy (in kcal or kJ/MJ)
you get by eating a certain amount. Below is a useful energy table:
| 1 gram carbohydrate | = | 4 kcal (16.7 kJ) |
| 1 gram fat | = | 9 kcal (37.7 kJ) |
| 1 gram protein | = | 4 kcal (16.7 kJ) |
Calculating energy in food
For example, the Nutritive Value declaration on a couscous, wheat flour,
pasta or rice package may say that 100 gram (g) contain 11g protein, 71g
carbohydrate and 1.3g fat - unprepared and dry. 11g protein 4 = 44 kcal (11x4),
71g carbohydrate = 284 kcal (71x4), 1.3g fat = 11.7 kcal (1.3x9). The total
amount of energy in 100g of this particular product was 340 kcal (284+11.7+44,
the box said 350 kcal), but only 284 kcal if you only count carbohydrates. To
get 500 kcal you need 125g of carbohydrates (125*4). A fast calculation tells
us we need 176g per day to get 500 kcal. A 500g package would last about 3
days. Rice, wheat flour, cous cous and pasta has basically the same nutritive
value.
Here is a list of different foods and how much complex carbohydrate (starch,
inulin, lichenin) they contain:
| Food | Carbohydrates | Carbohydrate energy |
 |
| 100g pasta (dry) | 75% (mostly starch) | 300 kcal |
| 100g raw potatoes | 17% (mostly starch) | 68 kcal |
| 100g raw Cow Parsley roots in August | 15% (mostly starch) | 60 kcal |
| 100g raw Orpine roots in September | 10% (mostly starch) | 40 kcal |
| 100g raw Cattail root marrow in November | 21% (mostly starch) | 84 kcal |
| 100g raw Dandelion roots in September | 23% (mostly inulin) | 92 kcal |
| All data taken from Stefan Källman's research |
Conserving carbohydrates
Another important thing is how you choose to consume energy. If you work
fast, hike hard, run, jog, stress, etc your muscles will almost exclusively use
carbohydrates as energy, but if you work and hike slowly (you can actually feel
where the limit is) for long periods of time your muscles will consume more fat
than carbohydrates (or at least equally much). Forget everything about what the
exercise fanatics say about pushing beyond the point of exhaustion to
loose fat - all native people in the world know that working fast and hard
consumes carbohydrates while working slowly for long periods of time
consumes fat.
I have lived off about 500 kcal worth of carbohydrates (primarily starch) per
day on several excursions and on nothing for about 30 hours on one excursion.
If you eat 500 kcal per day you feel clear in your head, but if you eat nothing
for a day you start to feel blurry and mistakes can easily happen because your
brain simply isn't getting enough energy (glucose).
Pictures of "natural" food...
Michel Blomgren
Survival enthusiast
michel.blomgren tigerteam.se
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