Exogenous Ketones (ExKs, henceforth) are (synthetic) ketone
bodies formed outside the human body (vs.
endogenous ketones, EnKs, synthesized internally).
members, Dr. Davis covers ExKs on this page:
Advanced Topics: Physiologic Ketosis, MCTs, and Exogenous Ketones
This present page is an overview of the ExK topic
for all readers.
This is not about ketone precursor products like
capryllic acid, coconut oil, ghee or MCT.
These are just dietary fats, although
useful and effective on a ketogenic diet, particularly MCT.
This is also not about “raspberry ketones” or
7-Keto DHEA, neither of which
are products that inherently contain ketone bodies.
Since 2013, ExK products have become
available that are being marketed directly to consumers.
These have a striking portfolio of possible benefits,
but they are so novel that any hazards from excessive and/or
chronic use may not yet be understood.
No adverse events have come to my attention so far, but
as Dr. Davis warns, some have dangerous levels of
calcium and/or potassium.
Although the currently available products may
not be optimal, Exks are currently being contemplated,
if not formally investigated, for:
||• athletics, esp. endurance
|• brain injury (bTBI, TBI, stroke)
non-toxic treatment or
|• epilepsy and seizure disorders generally
||• Friedreich’s ataxia,
|• grain withdrawal malaise avoidance
||• inflammation reduction generally
||• “keto flu” avoidance
|• lipidemias (some)
|• neurodegenerative diseases generally
toxicity (e.g. deep sea diving)
KD management adjunct
accelerating reversal of
I expect to populate the above table with local or external
links as I create or discover germane discussions on each
There are people using ExKs daily for mood and energy
enhancement. That might be a premature move. Some of
the products are being pitched for weight loss. That’s
probably misleading per se, but ExKs suppress appetite,
so might well aid in implementing the low-carb diets
coincidentally suggested for those products.
Research this topic thoroughly before
taking any of the available products
for any reason.
(This web page is not that research.)
Ketone Bodies Are
There are three ketone bodies. These occur naturally in human
metabolism, during extended fasting and
nutritional ketosis, and in the pathological states of
starvation ketosis and
diabetic ketoacidosis (DKA). They are:
- Beta-hydroxybutyrate (BHB, βHB or β-BHA)
are available at retail and as research compounds, and
so far are all salts, containing calcium,
potassium and/or sodium in non-trivial amounts.
- Acetoacetate (AcAc)
appear to be only available as research compounds
in ester form, such as
1,3 butanediol acetoacetate diester.
There are groups working to bring some of these to
- Acetone (Ac)
is the same chemical used in nail polish remover, and
although it’s considered a GRAS food
ingredient, and available in food-grade at retail,
I have found no indication that acetone is used as an ExK
(Searching on this is confounded by the fact that when
in ketosis, by any method, acetone is commonly spilled in
exhaled breath, so “acetone” dilutes web hits
in addition to nail polish.)
Don’t experiment with Ac.
Undiluted acetone is volatile and explosively flammable.
It’s considered a skin and eye irritant, and harmful
to the respiratory and central nervous system. LD50 (rat)
is 5.8 grams per kilogram of
Many body cells can use ketone bodies as an alternative to
glucose and free fatty acids (FFA) to make Adenosine
triphosphate (ATP). The brain in particular cannot
run on FFAs, requires some glucose, but can operate on
glucose plus ketones. Many investigators presently think
that the brain can run
(and run well) on up to 60% ketone bodies.
Ketone bodies can cross the
blood-brain barrier (BBB), whereas FFAs cannot.
This has profound implications for, among other things, neurological
disorders in which glucose is a suspect antagonist.
Although there is ample evidence for at least part-time
ketosis in all human populations, there is, as far as I can
tell, no ancestral case for
consumption of ExKs. Ketone bodies occur naturally
in foods, but at low levels, with acetone perhaps being the
Technically, ketone bodies are arguably considered fats, but
they are never included under Fats on Nutrition Facts panels.
This, plus the obscuration committed by many suppliers,
can make it difficult to know just how much ExK a product
Ketogenic diets (KDs) have been used therapeutically for a century
or more. Conditions in which they have been found useful include:
type 1 diabetes (T1D),
seizure disorders generally. The diet is also being investigated for
and to accelerate
reversal of T2D.
KDs are also popular with athletes (as carb-loading can be
avoided), people desiring to lose weight, and with
bio-hackers with various motivations.
The diet advocated by Undoctored and Wheat Belly is not
At 50 grams of net carbohydrate
per day, the Ud/WB diet is at
what is generally considered to be the borderline between
glycemic and ketogenic diets. People following a net50,
low/moderate protein, high specific fats diet are in
glycemic metabolism part of the time, and
ketotic metabolism part of the time (quite likely during
the fasting time that sleeping represents). CR/WB
can easily be made KD, by driving carbs lower and
keeping protein moderate.
For anyone who desires to increase their levels of ketone
bodies, the approach over the last century or so is a
fully ketogenic diet (KD). Reducing net carbs to 20 grams
or less per day, with some attention to protein intake,
usually suffices. Any calorie deficit is usually addressed
by increasing fat (not protein) intake, particularly fats that are
feedstock for ketone synthesis, such as MCTs.
sure to maintain intake of prebiotic
fiber on a full-time KD.
Excess protein needs to be avoided for KD, due to
gluconeogenesis - synthesis of glucose from protein.
The body can also synthesize glucose from fat.
This how the brain gets its required glucose when on
a strict KD that provides no exogenous glucose.
Exogenous Ketones Arise
Elevating blood levels of ketones to therapeutic levels can
be challenging, particularly in our current milieu of
high-carb, adverse-fat, food-like substances. The situation
that apparently sparked the development of ExKs was
oxygen toxicity seizures in deep sea divers. It was known
that ketosis was protective, but it was not thought practical to
keep operators on a full-time ketogenic diet.
Nutritional ketosis usually results in a ketone blood titer
in the range 0.5 to 3.0 mmol/L. This is as
measured by a blood test. Meters that test breath or urine
use completely different units of measure, and
are less reliable, primarily because they are measuring
spilled (excess) ketones, and secondarily because they
provide no insight into how much ketone is being consumed
for energy production.
It can take 2 to 4 weeks to get the
blood ketone level above 1.0, and some people have
difficulty getting above that. Using ExKs, it’s
apparently possible to get into the 3.0-5.0 range
without much difficulty - ketone levels can be brought
into the KD range this way even on a glycemic diet (but I’m
dubious that this latter is a wise idea absent a
specific problem being addressed).
Here’s a rodent trial of ExK effect on various diets:
of exogenous ketone supplementation on
blood ketone, glucose, triglyceride, and
lipoprotein levels in Sprague-Dawley rats
According to Patrick
Arnold (who appears to be the chemist
who formulated the first of the currently-available products)
“Your body can burn ketones
while on a normal diet
its just that your body won’t
make ketones on a normal diet“
and even on a glycemic diet, does so
(emphasis added by me). Apparently,
on ExKs, you won’t be burning any fat either.
A key question is: can an exogenous ketone body provide
the sought benefit even if the person is not on a ketogenic
For at least some seizures, the answer is:
This question then also arises for all the other conditions
for which KD is being explored. Will an ExK provide benefit
even if not on KD, and/or will it provide additional benefit
on a KD. We can’t presume the answer
is always yes.
Considerations for Use
With the current BHB salts, some product formulations
present potentially serious hazards due to excess
potassium, and/or undesired levels of calcium and/or
sodium. But let’s start with the active ingredient in
ExKs have now been in use since 2012, and available
at retail since 2013. They were able to come to
market quickly because BHB is considered GRAS. The
AcAc products in development apparently don’t have
that luxury, and are having to invest in safety
studies. If there have been adverse events with
the BHB ExKs, they have not been widely published
(or were mistaken for something else).
This, however, is no basis for complacency.
It’s easy enough to find articles skeptical of ExKs,
ketone esters dangerous?
This Ketogenic Rip-Off
Absent a specific problem needing resolution or
long-term therapy, I’m personally reluctant to
assume that chronic consumption of ExKs is necessarily
harmless. Unlike most of what those of us following
enlightened ancestral diets consume, there is obviously no
ancestral case for something that never existed
I will not be the least bit surprised if using ExKs
on a full-time glycemic diet in particular is a
On the upside, I would conjecture that for an endurance
athlete presently carb-loading, and perhaps for a
keto-adapted athlete feeding carbs into glycogen
depletion during an event, that it is net safer
to be keto-adapted, and feed ExKs for bonk-avoidance.
The KGZ Boost product might actually be suitable
for this if you can figure out how much BHB it provides.
Know what amounts of calcium, magnesium, potassium
and/or sodium are in any product under consideration,
Not all salts are present in all formulations.
Determine both grams for mineral (not total salt),
and percent DV (Daily Value) per mineral.
Note that some products violate labelling rules by
failing to specify both of these numbers (a reason
to reject a product per se).
We have already observed one ExK product with
80%DV (3.8 grams). On a diet with typical
amounts of food-sourced potassium, particularly if
routinely consumed at the upper end of the brand’s
“1-3 times a day” range, there is risk of hyperkalemia,
with possibly fatal cardiac consequences.
We have seen more than one ExK product with
140%DV (1400 mg) of calcium.
On the Undoctored program, we
want added Ca to be zero. Reject any
product than has more than
about 10 mg of calcium.
We have seen one product with 66%DV
(1600 mg) of sodium. Although the Undoctored
program does not support the consensus low-salt folly,
this is a significant fraction of the
conjectured 3000-6000 mg/day
range. If sodium is present, it needs to be factored into
whatever daily Na target you have in mind. Anyone with
a specific sodium/salt sensitivity also needs to
Whatever amount of Mg an ExK provides needs to
be accounted for in routine supplementation. So far, no
products have appeared with concerning levels (perhaps over
500 mg), but even 100 (which has been seen) would suggest cutting back
on your daily magnesium
has not yet tested any ExK products.
Here’s a question to ask your supplier of an ExK
Where is the BHB itself
The four most likely answers
are (with their translations):
- The BHB is made in the USA
(this is true for KetoSports)
- The “final product” is made in the USA,
or similar weasel-wording not responsive to the
(trans: but the BHB is from China)
- That’s “proprietary information”
or similar intellectual property /
trade secret babble
(trans: the BHB is from China)
- We’ll have to get back to you on that
(and when they don’t, the BHB is from China)
As mentioned earlier, the presently available ExK products
are all BHB salts: BHB with calcium, potassium, sodium,
magnesium, or some combination thereof, discussed above
The various products available may also contain:
gum acacia (an emulsifier),
gum arabic (an emulsifier),
mono and diglyceride esters,
prebiotic fiber (inulin),
soy lecithin (an emulsifier),
sweeteners (erythritol, inulin, stevia),
xantham gum (an emulsifier).
You’ll either have or need to develop a posture on
these. Is much of this just filler?
How much of it deliberately intended to prevent
figuring out how much BHB you get?
Does that “chocolate” product
actually contain any cacao?
Insist on a plain declaration of BHB per serving
(not “BHB salt” per serving, or total grams
For some brands, unless they start admitting it,
you need to ask:
How much actual BHB (not BHB salt) is in a serving?
Expect the usual proprietary misdirection.
OK, then, how much BHB salt is in the product?
Expect more stonewalling. Yes, you are buying the
product to get BHB. No, they will not tell how much
you are buying.
If you are an advanced amateur food formulator,
you can work out how much BHB is in some of the other
products. Thanks to the
ForeverGreen(Ketopia™ Ketonx) lawsuit
(now settled), we learned
how, from the declaration
of Dennis Jones, Ph.D
in that case. He didn’t work it out down to
the final BHB number, but for the specific product
examined at the time, it might be as little
as 8.6 grams.
I haven’t worked out the numbers for all the
concealing products. Personally, I consider the
withholding of this crucial information to be
a prima facie product disqualifier.
If you just plan to consume the product’s standard
serving size, economy is a simple matter of:
$daily = (net_price + shipping + tax) ÷ serving_count
In general you can expect to spend US$4.00/day
and up for this class of product, and then only if
one listed serving size per day meets your objectives.
If your intent is to reach a specific measured level
of ketones, however, you may need to adjust the serving
size. Then the question might become: how much does
a gram of BHB cost you? Some of the available brands
don’t want you to be able to run that calculation,
so you’ll have to work it out by trial and testing.
Ketone ester products haven’t even come to market
yet, in large part due to this issue. Ketone salts
have, but their formulations are still being
dialed in to address taste. Here’s
Dr. Peter Attia on his experience.
The original Prototype Nutrition KetoForce product
is highly alkaline (pH 10 to 11).
Follow the instructions on serving.
Now that Dr. Davis is minding the market, I’ve
given up trying to keep track of all the products.
In closing, this page was prepared to support comments
I might make on the ExK topic in various forums. I have
not used any of these products, and have no plans to.
I have no relationship with any of the brands mentioned.
I have no product recommendations to suggest at this time,
which in any case would be a hazard ranking list.
Bob Niland [disclosures]