Is Ketosis Dangerous? (Science of Fasting & Low Carb Keto)
Recently, low carb diets, intermittent fasting
and even prolonged fasting have become very
popular and they all have something in common.
They move you towards entering the state of
Ketosis is a state where your body is running
primarily on fat, fat from your diet or your
Ketogenesis is when Fats are broken down into
something called ketones.
These ketones (or ketone bodies) are usually
thought of as an alternate fuel source, because
instead of glucose, ketones are used to power
most tissues as well as the brain.
Sustaining ketosis means restricting protein
to less than 20% of your calories and carbs
to less than 5%
Unfortunately, there seems to be a lot of
confusion around ketones, most people have
been taught that ketosis is a dangerous unnatural
state that appears only during starvation
or in diabetics…
So with this video I’d like to clear up
some misunderstandings and, I’ll present
to you why entering this fat burning state
of ketosis can be perfectly natural, and might
even even be the preferred state for humans,
compared to having our bodies always running
off of carbohydrate.
To see how there can be so much confusion
around a topic like ketosis, let’s first
take a look at the story of the thymus gland.
Back around the 18th and 19th century, it
was hard to get cadavers for anatomical study.
People didn’t really like having their recently
deceased loved ones cut up for examination.
So people called resurrectionists were employed
by anatomists to exhume the bodies of the
Sometimes resurrectionists would even wait
near a funeral and snatch the body right then
Because of this, wealthy people would purchase
very well crafted lockable coffins and they
would hire armed guards to protect the graves
of their loved ones.
The 1832 Anatomy Act even said that if a person
died in a poor house, or their relatives could
not pay for medical expenses, their body was
to be immediately turned over to the anatomist
This meant that anatomists were much more
likely to get their hands on the body of a
poor person who couldn’t afford such measures.
So… what about the thymus?
Well, people facing the hardships that come
from being poor, are of course going to be
under a lot of stress.
Nowadays we’re very familiar with the fact
that chronic stress leads to all types of
diseases, and that it can atrophy certain
In the case of the thymus, stress can reduce
its size by as much as 75%.
So what ended up being recorded into the anatomy
books as a normal thymus gland was actually
a thymus that was severely reduced in size.
Then, in the 1900’s a german anatomist called
Paltauf was trying to find the cause of Sudden
Infant Death syndrome.
Manny middle and upper class babies were abruptly
dying of this.
So Paltauf examines the bodies of these higher
class babies and notices that their thymus
glands appear to be abnormally large.
So he concluded that if you wanted to be a
good parent you should irradiate the thymus
gland of your child to make it smaller and
prevent sudden infant death syndrome.
By the 1920’s all the the leading pediatric
textbooks were offering this advice.
Paltauf of course didn’t realize that he
was simply someone who had the rare chance
to look at the bodies of children whose thymus
was not affected by the chronic stress of
Unfortunately this misunderstanding persisted
well into the 1950’s, having several thousands
of people die from irradiation induced cancer.
So, what does any of this have to do with
Well, ketones also have the misfortune of
being misunderstood due to how they were discovered.
Physicians first noticed ketones in the latter
part of the 19th century, when they were noticed
to be in abundance in the urine of patients
in a diabetic coma.
It was understood that a vast overproduction
of ketones was responsible for the terrible
symptoms of something called diabetic ketoacidosis.
So for half a century ketones were thought
to be the very negative product of impaired
Only after technology and analytical techniques
improved did we understand that ketone bodies
are perfectly normal components of the blood.
Even if you’re not technically in ketosis,
Ketone bodies are always present in the blood
of a healthy person and their levels increase
the longer you go without food.
After an overnight fast, ketone bodies supply
2–6% of the body’s energy requirements,
while they supply 30–40% of the energy needs
after a 3-day fast.
Before we continue, being in ketosis through
fasting or diet is nothing like diabetic ketoacidosis.
Ketoacidosis involves exorbitant levels of
ketone production, far higher than what you
could achieve even when fasting for weeks.
Being worried about ketoacidosis through diet
or fasting is like worrying that eating at
a sushi restaurant is going to put you in
brief coma just like that one kid who chugged
a bottle of soy sauce on a dare.
So not only are ketones normally found in
healthy people, but it’s been found that
certain tissues prefer to use ketone bodies.
In fact, as is explained in the Biochemistry
textbook published by W.H. Freeman “Fatty
acids are the heart’s main source of fuel,
although ketone bodies as well as lactate
can serve as fuel for heart muscle.
In fact, heart muscle consumes acetoacetate
(a ketone body) in preference to glucose.”
Some people actually purposely enter ketosis
through fasting in order to improve mental
A study at the University of Cambridge concluded
that a ketogenic diet “improved physical
performance and cognitive function in rats,
and its energy-sparing properties suggest
that it may help to treat a range of human
conditions with metabolic abnormalities.”
I guess Plato figured this out for himself
when he said “I fast for greater physical
and mental efficiency.”
Going without food for better cognitive function
may sound ridiculous considering it was for
a long while thought that the brain can run
only on glucose ( carbohydrates).
George Cahill and his group at Harvard Medical
School demonstrated in 1967 that the brain
can use ketone bodies as a source of energy.
What he found was that during starvation,
ketones are the predominant fuel for the peripheral
tissues and the brain, with the brain deriving
more than two thirds of its energy from ketone
Despite this, the body still requires some
glucose, even when you aren’t eating anything.
For example red blood cells can’t run off
of ketone bodies because they don’t have
any mitochondria to metabolize them with.
But all of the body’s glucose needs are
met by the fact that the body can make its
own glucose, for example it can make glucose
from the glycerol backbone of fat.
For this reason, even during prolonged fasting,
people will keep a stable blood glucose level.
This also illustrates that there is actually
no dietary requirement for carbohydrate.
Of course vegetables and some fruit are very
important because they have all kinds of micronutrients
and fiber, but your body doesn’t actually
require the carbohydrate inside those foods.
I’m not necessarily saying a zero carbohydrate
diet is best, just that it’s very possible
to live without dietary carbohydrate assuming
you get enough fat and protein.
There are essential amino acids and there
are essential fatty acids – types of protein
and fat you must get from the diet.
However, there is no such thing as an essential
dietary carbohydrate – your body is perfectly
capable of making as much glucose as it needs.
In fact, in the absence of dietary carbohydrate,
the brain runs so efficiently off of ketone
bodies that you can drastically deplete glucose
levels of people in deep ketosis and it won’t
A 1972 paper describes an ethically questionable
study where overweight patients fasted for
2 months, putting them in deep ketosis meaning
they were producing a very large amount of
Insulin was then infused into these patients
until their blood glucose went as low as low
as 9mg per deciliter – a level that should
cause coma or death.
However, the patients didn’t really react
There was no particular change in cognition,
nor did their body react to the drastic drop
in blood sugar.
“The only people in the room who had palpations
and sweating and anxiety were the physicians.
The people who had the blood sugar levels
that should be associated with coma or death
were completely unphased.
Had completely normal mentation.
It is clear that the human brain is perfectly
happy with beta hydroxybutyrate as not just
its majority fuel, but essentially its sole
Actually anyone watching this video would
have, at at least one point in their lives,
been in a similar situation where blood glucose
is very low and ketone utilization is very
high in their bodies.
It’s estimated that a newborn’s brain
consumes on average between 60 and 71% of
its body’s energy budget.
Compare that to the lowly 25% of the body’s
energy budget an adult brain uses.
Despite this massive need for energy, a newborn’s
blood glucose level is incredibly low at around
35mg per deciliter.
This is half of the lower end of a normal
adult’s blood glucose level.
This means that the newborn’s brain would
have to be deriving more than half of its
energy from ketone bodies.
In his book on the health potential of ketones,
Dr. Muneta Tetsuo, director of Muneta Maternity
Clinic in Japan explains that pregnant women,
whether they are restricting carbohydrate
or not are producing higher than normal levels
By comparing the mother’s blood with the
newborn’s umbilical cord blood, he found
that out of 416 cases, 70% of babies were
born with even higher levels of ketones than
that of the mother.
By analyzing the villi that provide contact
with the mother’s blood to the fetal membrane,
Muneta deduced that the fetus must be living
in an environment of elevated ketones from
the start of pregnancy.
And, even a month after birth, babies on average
had a blood ketone level 5 times higher than
that of a normal person.
As Muneta wrote in his book: “Newborns are
living off of ketones!”
Not only is ketosis helpful for supplying
the energy needs of the newborn baby, it may
also be an important factor in the development
of the brain.
It’s been understood that exercise is beneficial
for the brain because it increases the level
of Brain Derived Neurotrophic Factor – BDNF,
which is a protein that promotes the growth
of new brain cells.
Because of this, Dr. John Ratey of Harvard
Medical School has given BDNF the nickname
of “miracle gro for the brain.”
However, the mechanism for how exercise triggers
BDNF was not clear for some time, until a
paper came out last year that was headed by
Assistant Professor of Biochemistry Dr. Sama
I think the title is quite straightforward:
“Exercise promotes the expression of brain
derived neurotrophic factor through the action
of the ketone body beta hydroxybutyrate.”
Growth of the brain is very important in a
more broad sense as well – growing a big brain
is of course what allowed us to become human.
And When it comes to human evolution, efficiency
is the name of the game.
That is our bodies had to develop methods
for more efficient extraction and utilization
of energy, mainly to support our big energy
One tradeoff for a bigger brain was a smaller
gut- less energy spent on the gut meant more
for the brain.
As is stated in a Public Library of Science
article titled “Man the Fat Hunter,” to adjust
for the high metabolic cost of a large brain
“…shrinkage in gut size was a necessary
… A shorter human gut, had evolved to be
more dependent on nutrient and energy-dense
foods than other primates.
A smaller gut is less efficient at extracting
sufficient energy and nutrition from fibrous
foods and considerably more dependent on higher-density,
higher bio-available foods that require less
energy for their digestion per unit of energy
/ nutrition released.”
This implicates fat as an important food source
because it is obviously very energy dense,
providing 9 calories per gram.
But the efficiency of using fat for fuel is
deeper than just calories.
Also, our brains’ power and capacity for
intellect comes not just from the increase
in size, but also from enhanced blood flow
and efficient use of oxygen.
Roger Seymour of the University of Adelaide
and his team found that bloodflow to the brain
increased at an unexpectedly rapid pace over
a period of 3 million years.
Seymour says: “While brain size was increasing
3.5 times, blood flow rate surprisingly increased
six hundred percent, from about 1.2ml per
second to 7ml per second.
…This indicates that our brains are six
times as hungry for oxygen as those of our
ancestors, presumably because our cognitive
ability is greater and therefore more energy-intensive.”
This would suggest that the most important
fuel for the brain is going to be one that
uses oxygen more efficiently.
And this is exactly what ketones do.
Dr. Richard L Veech found in 1994 that administering
ketone bodies to a rat heart led to a 25%
increase in hydraulic work, but a decrease
in oxygen consumption.
Theodore VanItallie explained this phenomenon
in a 2003 article by saying that the ketone
body beta hydroxybutyrate increases the efficiency
of energy production in the cell’s mitochondria.
If you were schooled in the states and attended
even a day of biology class, you would know
that mitochondria are the “powerhouses of
But is this improvement in efficiency happening
in the powerhouses of the brain cells?
Well, Vanitallie says that
“Studies of blood flow and oxygen consumption
in the brains of food-deprived obese human
subjects revealed values that were well below
the normal levels for adult human brains…
they suggest an increase in the metabolic
efficiency in human brains using ketoacids
as their principal energy source in place
People who have done extended fasts will sometimes
report a euphoric or drastically enhanced
state of mental clarity around day 6 or 7
– this is when ketone bodies have reached
a particularly high concentration: somewhere
over 5 millimolars per liter depending on
In essence ketone bodies may be a preferred
fuel source for the brain as they provide
more cellular energy per unit of oxygen compared
Getting more bang for your oxygen through
ketosis would be incredibly significant for
the development and maintenance of big brains.
Some of Dr. Dominic D’Agostino’s work
revolves around taking advantage of ketosis’s
efficient usage of oxygen in the cells.
His research touches on ketosis’s potential
for treating a variety of illnesses including
Epilepsy, ALS, Alzheimer’s , Parkinson’s and
even some cancers.
His initial research, funded by the Office
of Navy Research, was aimed at improving Navy
Seal Divers diving capabilities.
The most straightforward display of ketones
efficient use of oxygen is that simply by
being in the state of ketosis, Dr. D’Agostino
was able to double his breath hold time from
2 minutes to 4 minutes without any prior training.
To sum all this up, when fasting long enough,
or when protein and carbohydrate intake are
restricted enough, our bodies switch over
to breaking down fat and making ketones – potentially
the most efficient fuel that can be used by
The brain is a massive blood flow, oxygen
and energy hog that needs to constantly be
fueled – anything that could enhance energy
efficiency would be very important for the
survival of big brained humans.
Despite the evidence that our bodies and brains
may actually prefer to run on ketones, ketosis
is still frequently misunderstood as a potentially
Going back to the thymus story, surely children’s
thymuses wouldn’t have been irradiated if
the anatomical data of healthy children had
been available at the time.
And, maybe with ketones, the perception of
them would be totally different if the first
pieces of data didn’t come from a diabetic,
but say a healthy pregnant mother, or a healthy