Your body has an incredible ability to adapt to starvation by reducing your need for energy, making you hungry, and filling your mind with nothing but thoughts of food.

Today most of us don’t consider starvation a realistic possibility. We have
the exact opposite problemtoo much foodso we may not understand what
starvation can do to our bodies and our minds.

In an article titled “The Double Puzzle of Diabetes” in Nature, Jared
Diamond, a famous and influential biologist, shares a telling story about how
going without food was a perfectly normal part of life in our past:

So accustomed are we in the First World to regular meals that we
find it hard to imagine the fluctuating food availability that was
formerly the norm and remains so in some parts of the world.
I often encountered such fluctuations during my fieldwork
among New Guinea mountaineers still subsisting by farming and hunting.

For example some years ago, in a memorable incident, I
hired a dozen men to carry heavy equipment all day over a steep
trail up to a mountain campsite.

We arrived just before sunset, expecting to meet another group of
porters with food, and instead found that they had not arrived
because of a misunderstanding. Faced with hungry, exhausted
men and no food, I expected to be lynched. Instead, my carriers
just laughed and said, “OK, it’s no big deal, we’ll sleep on empty
stomachs tonight and wait till tomorrow to eat.”

Conversely, on other occasions when pigs were slaughtered for a
feast, the New Guineans would consume prodigious amounts of
food. This anecdote illustrates an accommodation to the pendulum
of feast and famine that was very necessary in times when
that pendulum swung often but irregularly—a situation that
was much more typical of our evolutionary history than the state
of plenty to which we are accustomed.

Later, when we talk about how your body makes you hungry and makes
you eat, even when you don’t want it to, think back to this section and give
your body some credit. How your body reacts to food in today’s environment
makes no sense at all, but it made perfect sense 25,000 years ago and has
allowed us all to survive through the most brutal trials

My information for this threat comes from a startling report of an experiment
on the effects of starvation published in 1950 by Ancel Keys and his
colleagues at the University of Minnesota.

In the first line of the report Keys says, “A full account of human experience
with starvation would cover all of history and would penetrate every
phase of human affairs.” Keys also observed that the history of man is in large
part a history of the quest for food. Given the important role of starvation in
history, it’s interesting nobody had yet done a scientific study on starvation.
Keys changed all that.

The experiment involved studying 36 men who volunteered as an alternative
to military service. The 36 young men were selected from a larger pool
of 100 volunteers and had the highest levels of physical and psychological
health. The men were also selected based on their commitment to the goals
of the experiment.

The implication is that these were men who were going to try their best
and were tough both mentally and physically. Your average person off the
street wouldn’t have reacted any better than the men selected. And in fact
might have reacted far worse. If the men developed problems we can’t say it
was because they were highly flawed test subjects.

For six months the men ate an average of 1,570 calories per day. On average
they lost approximately 25% of their starting weight. Pictures of the men
at the start of the study show a lean and healthy group. None of them were
overweight or even pudgy at the start of the study, so the weight loss was significant.
At the end of the study they looked like walking skeletons.

The World Health Organization defines starvation (the point at which
the body is dying) as 900 calories or less a day. Most commercial weight loss
programs target between 945 and 1,200 calories a day. Today the average male
eats about 2,700 calories per day.

When I first read that they’d eaten 1,570 calories a day I didn’t think it was
all that low. But I was very wrong. When you see what happens to these poor
fellows, you’ll wonder how anyone stays on a low calorie diet for long.
What happened to them? The men experienced powerful physical, psychological,
and social changes.

❖ They became obsessed with food, thinking, talking, daydreaming,
and reading about it constantly. They found it hard to concentrate
on their day-to-day life because their minds were filled by
thoughts of food and eating.
❖ A lot of their day revolved around planning how they would eat
their food. They devised ways of prolonging their eating experience
so they could get the most out of it. When it came time to eat
they would often eat in silence, devoting their total attention to
eating their food.
❖ A few had extreme mood swings. One man feared he was going
crazy and was losing his inhibitions.
❖ A few men mutilated themselves. One chopped off three fingers.
❖ Their physical endurance dropped by half. Their percentage of
body fat fell almost 70% and their percentage of muscle dropped
by about 40%.
❖ They began hoarding things like coffee-pots, hot plates, and
other kitchen utensils. They even collected non-food items like
old books, unneeded second-hand clothes and other junk. After
making these purchases, even when they couldn’t afford them,
they would often be puzzled as to why they bought such worthless
junk. One man even rooted through garbage cans looking for even
more “treasures.”
❖ Binge eating was a problem for some of the men.
❖ Forty percent of the men considered entering a cooking related
job after the end of the experiment. They hadn’t considered cooking
before the study. Three eventually became chefs and one went
into agriculture.
❖ The men’s resting metabolic rates declined by 40%, their heart
volume shrank by about 20%, their pulses slowed and their body
temperatures dropped. They had complaints of feeling tired and
hungry; having trouble concentrating, and of impaired judgment
and comprehension. One man said it was as if his “body flame
[was] burning as low as possible to conserve precious fuel and still
maintain life process.”
❖ They were cold all the time. To conserve energy, their temperature
dropped from the normal 98.6 degrees to an average of 95.8 degrees.
❖ The average heart rate slowed to 35 beats per minute. When they
started the experiment the average was 55 beats per minute.
❖ Their testes shrunk and they lost all interest in sex. People often
think sex is the strongest drive, but it’s dispensable when you are
starving.
❖ They had physical signs of accelerated aging.
❖ The men became nervous, anxious, apathetic, withdrawn, and
impatient. They became self-critical with distorted body images
and even felt overweight, moody, emotional and depressed. They
lost their ambition and feelings of adequacy. Their cultural and
academic interests narrowed. They didn’t care about how they
looked anymore. They became loners and neglected important
relationships. They lost their senses of humor, love and
compassion.
❖ When the men started eating again and regaining weight, many
began having signs of heart problems, congestive heart failure
and high blood pressure.
❖ At the end of the experiment, the men were at nearly the same
weight as at the start of the experiment, which was some of the
first evidence showing humans may have a natural weight setpoint.
Losing weight didn’t reset their set-point to a lower level.
The weight they regained was mostly fat; they ended up with
approximately 140% of their original body fa

What can we take away from the amazing results of this unique
experiment?

❖ The men weren’t truly starving. In the experiment they called it
semi-starvation. Can you imagine how consumed with food you
would be if you were truly starving? Unfortunately, you don’t have
to imagine. In the Leningrad famine of 1941, we have a real life
example of what happens when people starve. Hitler’s Siege of
Leningrad lasted 872 days. Non-manual workers ate an average of
473 calories a day. When the siege started, hungry people first ate
the zoo animals. Next they turned to household pets. Then they
ate wallpaper paste and boiled leather. When that was gone they
ate corpses. And eventually even the living.
❖ Your body has an incredible ability to adapt to starvation by
reducing your need for energy and by making you hungry, and
filling your mind with nothing but thoughts of food. This is often
called being in starvation mode. If you were just a dumb computer
you would simply note you were starving and then die. But
that’s not what happens. Your body has ways of getting you to eat.
These aren’t extra special abilities it only uses sometimes, but
capabilities your body uses every day to get you to eat. When the
desire to eat pops up in your mind, where do you think it comes
from? It’s your brain telling you to eat so you won’t starve. The longer
you go without eating, the stronger the urge becomes. In some
people these urges are strong all the time.
❖ If your body didn’t have the ability to conserve energy and
obsess you with thoughts of food, then you would simply die
when food became scarce or when your attention was focused
on other interesting events in your life. The starvation study
shows how humans become more focused on food when starved
and how other goals important to the survival of the species,
like sex, become unimportant in comparison. Food is the most
important thing in your life. Don’t forget that. Don’t blame yourself
for it either.
❖ If you think you are going to stay on a low calorie diet for any
length of time, then you are fooling yourself. Think about how
the body reacts to any hint of starvation. Trying to lose weight by
eating a lot less won’t work, your body won’t let you. You’ll stop
losing weight.
❖ The physical performance of the men deteriorated greatly, yet
their mental performance did not. Although the men thought
their minds performed worse, tests showed differently. Even when
starving, your body maintains your ability to think because your
mind is your best survival tool.
❖ Another interesting conclusion from the study is that people varied
a lot in how they handled starvation. Some coped well and
others didn’t. This goes to show we are all different. What works
for you may not work for someone else. Your personal call of hunger
may not be the same as anyone else’s. Try to remember that
when judging your own difficulties of losing weight and staying on
a diet.
❖ One of the most interesting implications of the experiment is
that your body doesn’t care about your willpower. It will defend
a set-point weight with all the tools at its disposal. Your body
doesn’t seem to adjust to a new lower weight. It wants to gain the
weight back.

Todd Tucker wrote an excellent book on this study called The Great
Starvation Experiment. In summing, Tucker says:

When he [Keys] looked at the big picture drawn by the thousands
of tests, graphs, and X-rays they had created, Keys concluded
that the human body was supremely well equipped to deal with
starvation. Eons of erratic food supplies and natural disasters
had built into the body an array of mechanisms for conserving
energy until the floodwaters receded, the crops were restored, or
the drought ended. In later years Keys would say it was the most
significant finding of the study. The human body was very, very
tough (emphasis added).