The story of life on earth is a story of starvation.
The story of life on earth is a story of starvation.

Ash from massive volcanoes and asteroids block out the sun,
Ash from massive volcanoes and asteroids block out the sun,

killing the plants, which then killed most everything else.
killing the plants, which then killed most everything else.

As Darwin pointed out though, from this “war of nature,
As Darwin pointed out though, from this “war of nature,

from famine and death, the most exalted object that we
from famine and death, the most exalted object that we

are capable of conceiving” arose—namely us.
are capable of conceiving” arose—namely us.

We are “particularly well adapted to prolonged fasting.”
We are “particularly well adapted to prolonged fasting.”

Evolving in a context of scarcity is believed to have shaped
Evolving in a context of scarcity is believed to have shaped

our exceptional ability to store
our exceptional ability to store

large amounts of calories when food is available.
large amounts of calories when food is available.

Of course, now our ability to easily pack on the pounds
Of course, now our ability to easily pack on the pounds

is leading to modern diseases like obesity and type 2 diabetes,
is leading to modern diseases like obesity and type 2 diabetes,

but without the ability to store so much body fat
but without the ability to store so much body fat

we may not have made it to tell the tale.
we may not have made it to tell the tale.

And it’s not just asteroids millions of years ago.
And it’s not just asteroids millions of years ago.

“All of Upper Egypt was dying of hunger,” reads an inscription
“All of Upper Egypt was dying of hunger,” reads an inscription

on an Egyptian tomb from about 4,000 years ago,
on an Egyptian tomb from about 4,000 years ago,

“to such a degree that everyone had come to eating his children...”
“to such a degree that everyone had come to eating his children...”

Or, just hundreds of years ago –
Or, just hundreds of years ago –

parents killed their children and children killed their parents
parents killed their children and children killed their parents

and ate them; "the bodies of executed criminals
and ate them; "the bodies of executed criminals

were eagerly snatched from the gallows.”
were eagerly snatched from the gallows.”

Wiping out as many as two-thirds of the population of Italy,
Wiping out as many as two-thirds of the population of Italy,

one-third of the population of Paris.
one-third of the population of Paris.

So, we don’t have to go back to ancient history.
So, we don’t have to go back to ancient history.

Even the most secure and affluent populations of today
Even the most secure and affluent populations of today

need only trace their history back a short distance.
need only trace their history back a short distance.

For example, nearly 200 famines in Britain
For example, nearly 200 famines in Britain

over the last 2,000 years.
over the last 2,000 years.

Now, we tend to be suffering from too much food,
Now, we tend to be suffering from too much food,

which carries its own problems, but might there be
which carries its own problems, but might there be

any negative consequences to not ever starving?
any negative consequences to not ever starving?

This was a question raised 50 years ago.
This was a question raised 50 years ago.

I mean, if our physiology is so well-tuned to periodic starvation,
I mean, if our physiology is so well-tuned to periodic starvation,

maybe by eliminating that we may be doing harm to our overall well-being?
maybe by eliminating that we may be doing harm to our overall well-being?

We just didn’t know.
We just didn’t know.

The lack of research in the area of starvation was attributed
The lack of research in the area of starvation was attributed

to the “difficulty of securing willing human subjects."
to the “difficulty of securing willing human subjects."

So, what little we had came from unwilling subjects.
So, what little we had came from unwilling subjects.

Physicians within the Warsaw Ghetto made detailed accounts
Physicians within the Warsaw Ghetto made detailed accounts

before they themselves succumbed; or Irish Republican prisoners
before they themselves succumbed; or Irish Republican prisoners

starving themselves to death after up to 73 days on hunger strike.
starving themselves to death after up to 73 days on hunger strike.

But starvation isn’t necessarily the same as fasting,
But starvation isn’t necessarily the same as fasting,

an issue raised in medical journals over a century ago.
an issue raised in medical journals over a century ago.

Starvation is normally a forced, mentally stressful,
Starvation is normally a forced, mentally stressful,

and chronic condition, whereas therapeutic fasting is voluntary,
and chronic condition, whereas therapeutic fasting is voluntary,

limited in duration, and usually practiced by people
limited in duration, and usually practiced by people

who start out with adequate nutrition.”
who start out with adequate nutrition.”

Therapeutic fasting?
Therapeutic fasting?

Where did we get this idea of fasting therapy,
Where did we get this idea of fasting therapy,

fasting for medical purposes?
fasting for medical purposes?

It may have originally arose out of the observation
It may have originally arose out of the observation

that when people get acutely ill they tend to lose their appetite;
that when people get acutely ill they tend to lose their appetite;

so, maybe there’s something in the body’s wisdom to stopping eating.
so, maybe there’s something in the body’s wisdom to stopping eating.

That’s presumably where the whole “starve a fever” folklore came from.
That’s presumably where the whole “starve a fever” folklore came from.

There was this sense that fasting affords physiological rest for the body,
There was this sense that fasting affords physiological rest for the body,

not just the digestive tract, but throughout,
not just the digestive tract, but throughout,

allowing the body to concentrate on healing.
allowing the body to concentrate on healing.

It was evidently an open secret that veterinarians
It was evidently an open secret that veterinarians

used to hospitalize dogs only to fast them back to health;
used to hospitalize dogs only to fast them back to health;

and so maybe, the theory went, it might work for people too.
and so maybe, the theory went, it might work for people too.

Beyond just freeing up all the resources that would normally
Beyond just freeing up all the resources that would normally

be used for nutrient digestion and storage,
be used for nutrient digestion and storage,

there’s this concept that during fasting our cells
there’s this concept that during fasting our cells

switch over to some sort of protection mode.
switch over to some sort of protection mode.

Why would fasting reduce free radical damage and
Why would fasting reduce free radical damage and

inflammation and bolster cellular protection?
inflammation and bolster cellular protection?

It’s the that-which-doesn’t-kill- us-makes-us-stronger concept
It’s the that-which-doesn’t-kill- us-makes-us-stronger concept

known as hormesis.
known as hormesis.

So, that’s kind of the opposite of the let-the-body-rest theory.
So, that’s kind of the opposite of the let-the-body-rest theory.

It’s more like let-the-body-stress.
It’s more like let-the-body-stress.

The stress of fasting may steel the body against
The stress of fasting may steel the body against

other stresses coming your way.
other stresses coming your way.

This was demonstrated perhaps most starkly in a set of cringe-worthy
This was demonstrated perhaps most starkly in a set of cringe-worthy

experiments in which mice were blasted with Hiroshima-level
experiments in which mice were blasted with Hiroshima-level

gamma radiation sufficient to kill 50% within two weeks,
gamma radiation sufficient to kill 50% within two weeks,

but of the mice who had first been intermittently fasted
but of the mice who had first been intermittently fasted

for six weeks before, not a single one died.
for six weeks before, not a single one died.

It’s this kind of dramatic data that led to extraordinary claims,
It’s this kind of dramatic data that led to extraordinary claims,

like therapeutic fasting could drive half of all doctors out of business.
like therapeutic fasting could drive half of all doctors out of business.

But you don’t know, until you put it to the test, which we’ll explore next.
But you don’t know, until you put it to the test, which we’ll explore next.