Starvation and Survival
By
Jamie Hale
It has been 24 hours, and you still have no idea where you are. You’ve
concluded that you’re lost. You may be lost for days, weeks, or even longer.
Stay calm and decide what you need to do to survive. You need shelter, water,
and food. You’ve already built an efficient shelter and located a water source,
but you only have one Powerbar. Questions begin to race through your head. What
happens to the body during starvation? How long can I survive without food? How
do I increase survival time without food?
Starvation
Starvation occurs when the body is deprived of food (lack of fuel to support
life). There are varying levels of starvation. The metabolic conditions that
occur during starvation vary as starvation progresses.
When nutrient supply to the body is stopped, the body’s first priority is to
provide glucose for the brain. In the early stages of starvation, glucose can be
supplied by the breakdown of liver glycogen (stored glucose molecules). When
blood levels of glucose drop, liver glycogen is broken down and shuttled to the
bloodstream (Gropper 2000). The liver stores 100–110 grams of glycogen. After
approximately 10–18 hours of food deprivation, liver glycogen is depleted
(varies with activity levels).
Gluconeogenesis also contributes to glucose production. Gluconeogenesis is
the generation of glucose from non-carbohydrate sources (e.g. lactate, pyruvate,
most amino acids, glycerol, and propionate) (Hale 2005). The vast majority of
gluconeogenesis takes place in the liver and, to a smaller extent, in the
kidney.
In the early stages of starvation, amino acids derived from muscle protein
are major contributors to gluconeogenesis. As starvation progresses and the body
begins to rely more on free fatty acids and ketone bodies for fuel, protein
breakdown decreases. Sparing valuable protein becomes the second priority of the
body (Gropper 2000). Maintaining a specific level of protein is essential
because proteins have many vital functions including the production of
antibodies (to fight infection), hemoglobin (to carry oxygen to tissues), and
enzymes (to assist in many life-sustaining reactions), and the ability to repair
muscle, particularly of the heart.
As starvation continues, the body begins to decrease its metabolic rate,
which decreases calorie expenditure. Tissues such as the heart and skeletal
muscle switch from glucose to free fatty acids for fuel. Most tissues of the
body can use free fatty acids for fuel. The brain is one of the few tissues that
can’t. The liver produces and releases ketone bodies as a source of energy.
Ketone bodies become a major fuel for the brain when they are produced in
sufficient amounts. After approximately three weeks of starvation, up to 75
percent of the brain’s fuel is derived from ketone bodies. It’s a common myth
that the brain can only use glucose for fuel. Let me repeat that. It isn’t true
that the brain can only use glucose for fuel. In fact, ketogenic diets are
often used for treatment with some neurodegenerative disorders. In the fed
state, the brain uses only glucose. But to reiterate, this changes when
starvation occurs. The body’s transition to the use of ketone bodies and fatty
acids for fuel lessens the demands on its protein and glucose supply. After
approximately three weeks of starvation, most of the body’s fuel demands are met
by free fatty acids (92–93 percent).
Survival time without food
The major determinant of survival time without food is body fat levels.
Another factor determining survival time is energy expenditure. In the 19th and
early 20th century, it was thought that weight losses of 40–50 percent of
initial body weight would result in death. The suggestion of a critical level of
weight loss was soon dismissed as data revealed successful weight loss with
percentages exceeding 50 percent (United Nations University). Successful weight
losses of up to 76 percent of body weight have been reported in obese subjects.
Weight loss percentages with lean individuals are significantly lower. Two
important predictions concerning starvation are obese individuals will survive
longer than lean individuals when deprived of food, and during starvation, obese
individuals oxidize less protein than lean individuals.
How long can a human survive without food? It depends. An obese subject
studied by Stuart and Fleming (1973) successfully fasted for 382 days. He
entered the Guinness Book of World Records for the longest “total” fast (United
Nations University). Other authors have reported successful fasts in obese
subjects of 100–300 days. In general, survival time in lean subjects is less
than 80 days. Newspaper reports indicate that in 1981, a Northern Ireland Fester
died of starvation in 45 days. The decreased survival time was probably due to a
previous gunshot wound to the hip. The body’s attempt to fight off illness
increases calorie expenditure, thus speeding up the starvation process.
Individual responses to starvation vary. Much of what we know about
starvation comes from studies on obese subjects. Much of the information found
in these studies can’t be appropriately applied to lean individuals.
Starvation-induced death is generally caused by a massive loss of bodily
proteins. These losses cause decreases in vital organ size and function.
Micronutrient deficiencies can also contribute to the critical effects of
starvation that ultimately result in death.
Preventing starvation
Unless you’re very lean, ill, or lost for a prolonged period of time (without
food), you probably will not die from starvation. It is good to prepare for the
worst case scenario though. I’ve provided some tips below to ensure you don’t
die of starvation in the wilderness.
Prevention tips
· Tell someone (or maybe a few people) where you’re going and when
you will return.
· Be able to identify edible plants and prepare them for eating.
· Be prepared to hunt or fish for food (includes being familiar with
primitive methods).
· Familiarize yourself with animal tracking techniques (assist in
hunting and identifying the type of animals in the area).
· Don’t expend unnecessary amounts of energy (e.g. don’t use a bow
and drill to start a fire if you have matches).
· Stay warm (increased shivering increase calorie expenditure).
References
- Gropper S (2000) The Biochemistry of Human Nutrition. 2nd
edition. Wadsworth.
- Hale J (2005) The Carbohydrate Files. MaxCondition Publishing.
- United Nations University. Effect of Starvation and very low calorie
diets on protein-energy interrelationships in lean and obese subjects.
Accessed December 3, 2008 at:
http://www.unu.edu/unupress/food2/UID07E/uid07e11.htm.
Jamie Hale is a sports conditioning coach, author, gym owner, and fitness
and nutrition consultant. He has contributed to numerous exercise and sports
publications (nationally and internationally) and has authored four books. He is
currently working on his fifth book titled, Protein Essentials: What Every
Athlete Needs to Know. Jamie is a member of the World Marital Arts Hall of Fame
in recognition of his conditioning work with martial artists. He is considered
by most in the industry as a specialist in agility and sledgehammer training and
is also known for his ability to get bodybuilders as lean and dry as bone for
competition. To learn more about Jamie, visit his website at
www.maxcondition.com or contact him by phone at (859) 737-2753. He is available
for seminars and camps as well.
Elite Fitness Systems strives to be a recognized leader in the strength
training industry by providing the highest quality strength training products
and services while providing the highest level of customer service in the
industry. For the best training equipment, information, and accessories, visit
us at www.EliteFTS.com.
