Ketones are the products of the breakdown of fats in the body. Under a state of carbohydrate depletion, blood sugar is reduced, insulin levels fall, glucagon and cortisol rise, and fatty acids (FFAs) are liberated into the blood through a process called lipolysis. The increase in blood levels of FFAs is then sensed by the body, and FFAs are then transported to the liver and used in the production of ketone bodies. Three ketones exist: Acetoacetate (AcAc), Beta-hydroxybutyrate (BHB), and Acetone.
Being in ketosis simply means that you have elevated levels of ketones in your blood, usually agreed upon at 0.5mM. Typically, this means elevated AcAc or, more commonly and in greater amounts, BHB.
BHB and AcAc are the ketones mostly referred to when talking about ketosis and, as we will see later on, ketone supplements.
BHB is the ketone present at the highest levels in the blood of a body in ketosis. This is significant for two reasons. For one, BHB is more stable than AcAc, and can be transported through the blood to other organs and tissues much more effectively. AcAc can be spontaneously broken down when it’s in the blood, where it forms acetone—a metabolic “waste product” that we excrete in the breath. We can’t use much acetone for energy.
But this doesn’t make AcAc any less important.
In fact, AcAc is the “parent” ketone body—it’s what the body produces first, when the body is entering ketosis, and serves as the precursor for BHB. AcAc produced in the liver is converted to BHB, and then shuttled out and delivered elsewhere. A small amount of AcAc does travel through the circulation to be used as a fuel source, just to a lesser extent than BHB.
The science of ketones can be confusing
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Endogenous vs. Exogenous Ketosis
“Am I in ketosis?” This question has a straightforward answer. As mentioned, typically a blood ketone level >0.5mM signifies that the body is producing ketones (or is in ketosis, depending on the route taken).
Route taken? Correct. There are two ways to achieve ketosis—endogenously or exogenously.
Endogenous ketosis (“endo” meaning within”) is achieved through a low-carb high-fat diet (i.e. ketogenic diet) or fasting, in which the body produces its own ketones. The stimulus is dietary carbohydrate restriction, and the response is that we start to burn fat, leading to (eventually) an outflow of ketones from the liver. Since diverse signaling pathways are activated in order to activate endogenous ketosis and in response to it, diverse physiological benefits also occur.
In contrast, exogenous ketosis (“exo” meaning outside) is achieved through the use of dietary ketone supplements and/or intake of certain types of dietary fats. These supplements can boost ketone levels either directly (ketone supplements) or indirectly (MCTs) but either way, elevate levels of blood ketones. Ketosis achieved exogenously can occur even in the absence of a ketogenic diet or prolonged fast. Sounds too good to be true.
Ketosis might be ketosis, but the profiles used to achieve endogenous and exogenous ketosis vary drastically, and therefore have different benefits. There is something to be said about triggering the body to naturally produce ketones vs. “artificial” induction of ketosis. In the former, you’re forcing the body to be “ketogenic” whereas in the latter, you’re in ketosis, but not “ketogenic.” There are benefits to both.
Exogenous ketones are an alternative to physiological ketosis, and can be used in diverse ways to achieve certain mind and body states, almost like ketosis on cue.
While supplements are only chemically synthesized versions of ketones, the structure and function are essentially the same.
But, structural similarities aside, exogenous and endogenous ketosis have varying effects on the body. For instance — exogenous ketone supplementation is likely best for those trying to meet the needs of a ketogenic diet, improve sport performance, or further increase ketone levels on a ketogenic diet or a fast. However, the health benefits of ketosis like increased fat metabolism, weight loss, and some of the other metabolic benefits might only come from lifestyle changes like fasting or a ketogenic diet.
Why Use Exogenous Ketones?
Before diving into the specific forms of exogenous ketones and the nuances of each, let’s discuss some of the general reasons one might choose to use exogenous ketone supplements in the first place.
One of the primary reasons to use exogenous ketones may be to enhance the effects of your low-carb ketogenic diet or intermittent fasting regimen. These practices will likely have you in a ketogenic state already. To further enhance the benefits many people claim to feel when ketogenic/fasting— like mental clarity, sharpness, lower fatigue—exogenous ketones can be superimposed, which essentially means going “deeper” into ketosis.
Exogenous ketones might also be a helpful aid to transition into ketosis when starting out on a ketogenic diet.
Many cite the “keto flu” as a badge of honor one must experience when entering into ketosis. When the body is first adapting to a diet very low in carbohydrates, and not yet fully adapted to burning fat/utilizing ketones, you may experience symptoms like nausea, headache, weakness, irritability, muscle soreness, difficulty sleeping, and irritability. Using an exogenous ketone supplement during your transition into keto may mitigate some of these symptoms by ramping up the level of ketones in your blood to use as an energy source for brain and body. It may also improve energy levels early on in ketosis before adaptation occurs.
And finally, whether endogenously produced or not, ketones have diverse signaling roles in the body that could benefit mental and physical health, metabolism, and longevity, as well as serving as a cellular energy source.
Medium-Chain Triglycerides (MCTs)
MCTs aren’t ketones, but rather a type of fat molecule comprised of a glycerol bonded to three medium-length fatty acids (FAs) that are 6 – 12 carbons in length.
Why are we talking about these then, if they aren’t ketones?
Well, MCTs are actually pretty good sources for the body to breakdown and turn into ketones. When it comes to ketone production, not all fats are created equal, and longer isn’t always better. Size matters.
The source of fat in MCT oil and other MCT containing fats (like coconut oil) is the most efficient type for producing ketone bodies. The medium chain fats go right to the liver, where they require less work to break down compared to long- and short-chain fatty acids.
You can get your MCTs in two ways: through an MCT oil or powder, or by consuming a rich (and tasty) source of MCTs such as coconut oil.
The MCTs include caproic acid (C6), caprylic acid (C8), capric acid (C10), and lauric acid (C12). Of these, caprylic acid (C8) is preferred for ketone production, and optimally what you should look for when purchasing an MCT oil supplement. Lauric acid is the MCT found most abundantly in coconut oil (about 50% of the total MCTs).
Because of its efficacy, we selected pure C8 a part of the base (along with prebiotic acacia fiber) of HVMN’s MCT Oil Powder. It’s 100% natural, real food, harvested sustainably and carefully purified into pure C8. No additives, no artificial ingredients, zero net-carbs. It’s a great source of MCT without all the other junk you might find in inferior products.
Benefits of MCTs: What Does the Research Say?
Though marketed as a supplement, one benefit of MCTs is that they’re derived from all natural food sources. For those who are “anti-synthetic,” you have nothing to fear from MCTs.
A powerful benefit of MCT ingestion, like ketone supplements, might be appetite suppression.
MCTs might help blunt hunger and help with calorie and portion control, thereby indirectly helping you adhere to a diet and thus meet your body composition goals.
One study demonstrated that acute intake of MCTs led to reduced food consumption at lunch while also reducing the blood glucose and triglyceride response to the meal. Interestingly, MCT oil also has a “satiating” effect that is not observed with coconut oil.
MCTs might directly aid in weight loss as well, outside of general satiety.
This action might be due to the fact that MCT oil supplementation can increase energy expenditure, fat oxidation, metabolism, and thermogenesis (body heat production) which leads to a lower body weight and more fat loss over time. Furthermore, MCT supplementation might have metabolic benefits like lowering LDL cholesterol and increasing lipoprotein particle size.
Disadvantages of MCTs: What Does the Research Say?
Large amount of MCTs, like any supplement, have been reported to cause gastrointestinal side effects.
This might be an issue, since in order to raise blood BHB to adequate levels to reach ketosis, a high amount of MCTs (and even more coconut oil) must be consumed. Remember, MCTs must be metabolized first before they become ketones—they don’t directly elevate blood ketone levels. Most studies show that MCT consumption elevates blood BHB to levels around 0.5 – 1mM.
Let’s not forget about calories. One downside to coconut oil and MCTs is that they’re fairly calorie-dense, so it’s important to keep track of your macros and calories when using supplements. Compared to ketone salts and ketone esters, MCTs result in much lower levels of ketosis, but they may be a more cost-effective and approachable option for new keto dieters.
Coconut Oil vs. MCT Oil for Ketosis
MCT oils and powders are the most concentrated sources of MCTs and thus might be your best option if you’re hoping to get into ketosis. MCT oil also has different proportions and types of MCTs compared to coconut oil; with a bit more C8 (caprylic acid) and a bit less C12 (lauric acid).
There is evidence that the satiating effect of MCTs might be more potent when they come in the form of a concentrated MCT oil compared to coconut oil.3 If you’re looking for something to help with appetite suppression or a small snack that will “tide you over” more effectively, search for a high-quality MCT oil or powder.
However, in terms of taste and versatility, coconut oil takes the keto-cake. You can use coconut oil in virtually anything, from cooking veggies and meats, to adding in smoothies and protein shakes. The options are endless (and delicious).
Ketone Salts
They’re not something you sprinkle on top of your roasted vegetables or use to season your stew.
Rather, ketone salts are a supplement that comes in powder form, to be mixed (traditionally) in some type of liquid for consumption. Ketone salts contain a ketone (usually BHB) bound to a mineral salt; usually sodium, potassium, calcium, or magnesium or an amino acid like lysine or arginine.
Ketone salts are one way to raise blood ketone levels. Studies have shown that ketone salt ingestion can elevate blood BHB levels to around 0.6 – 0.8mM (i.e. ketosis).
Benefits of Ketone Salts: What Does the Research Say?
Ketone salts aren’t a new “invention.” They’ve been around for quite some time, and early studies of these ketone supplements were conducted in children with metabolic disorders, where they showed efficacy in inducing ketosis and an improvement of symptoms like better cardiac performance and cognitive function due to better ability to oxidize fatty acids.
Similar levels of ketosis around 0.5mM have been observed in rats given BHB ketone salts. Health benefits such as improved blood glucose, beneficial changes in lipid biomarkers and fat mass, and reduced anxiety-like behavior were noted in multiple different studies.
Disadvantages of Ketone Salts: What Does the Research Show?
Compared to other ketone supplements, ketone salts might not deliver as much “ketogenic power”—meaning they don’t elevate blood BHB to levels as high as other products.
For example, one study showed that blood BHB was raised to around 1mM following ketone salt ingestion, while the same amount of BHB provided from a ketone ester raised blood ketone levels to 2.8mM. The salt also provided a greater amount of the L-isomer of BHB as opposed to the D-isomer. While not going into the deep end of structural chemistry, L-BHB is like a mirror image of D-BHB (like your left and right hand). They are what is known as optical isomers. While structurally similar, L-BHB may not have the same pattern of metabolism nor the benefits that D-BHB has.
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