What is Ketosis?

If you’ve got questions about ketosis, you’ve come to the right place. We created this guide to answer all your questions and explain everything you need to know about ketosis — all in one place!

To skip to a specific section of this guide, just click on that topic link here:

(Note — Consult your healthcare provider before beginning a new diet or taking action based on any information provided here. Review our Medical Disclaimer here.).

Ketosis Explained — the Short Version

If you’re looking for a quick and basic understanding of ketosis, this section has exactly what you need (although we recommend you also check out the in-depth explanation of ketosis here).

Here are 7 simple steps to understanding the basics of ketosis:

  1. When an individual eats a “normal diet” (high in carbohydrates) they get energy by utilizing glucose (sugars).
  2. When a person restricts the amount of glucose they take in (such as from eating a ketogenic diet) their body needs to replace the energy they were getting from glucose, with something else.
  3. The human body has a “back-up” plan it can use to get the fuel it needs, when it’s not getting enough glucose.
  4. That back-up plan is a process called “ketosis.”
  5. Ketosis is the metabolic state when your body has “switched over” to getting some of the fuel it needs from “ketone bodies,” rather than glucose.
  6. Ketone bodies are a group of three chemicals that are produced by the liver using fatty acids.
  7. Researchers have found many benefits from having the body rely on ketones instead of only glucose. And that’s why the keto diet has gotten so popular!

That’s it — just 7 steps to understanding ketosis!.

Ketosis Explained — the Longer Version (with just a little science included)

Getting Energy from Food — While Not in Ketosis

Let’s start with an overview of the process the body uses to get energy from food, when someone consumes the standard American diet (which usually includes a lot of carbohydrates) and is not in ketosis. The food they eat is broken down in three stages so it can ultimately be used for energy:

  1. Digestion — Digestion occurs either in the intestine, outside our cells, or in a specialized place inside our cells called the lysosome. It needs to occur in either of these two places to keep the rest of your body safe from potential hazards that might be in your food.

    The digestion stage can be compared to waiting for customs screening at the airport. Once you are scrutinized to their satisfaction, they stamp your passport which allows you to pass through on your way

    During digestion, the large molecules in your food are broken down further into their molecular sub-units:

    Proteins ===> Amino Acids
    Carbohydrates ===> Sugars
    Fat ===> Fatty Acids & Glycerol



    These sub-units allow them access to the rest of your body and move into stage 2 of the process.

  2. Glycolysis — Glycolysis is a chain reaction that takes the sugars from the first stage of digestion (which originated in the form of carbohydrates) and converts them into molecules of pyruvate and a form of cell energy called “adenosine triphosphate” (“ATP” for short).

    Each molecule of sugar that is broken down by glycolysis yields two molecules of ATP.

    These ATP molecules are stored inside your cells to be used as energy. If you could open a cell and see inside, you’d find that there are roughly 109 molecules of ATP stored in a typical cell — waiting to be used for energy at any given moment. That’s a TON!

    However, this stored ATP is turned over every 1 to 2 minutes so your body needs a consistent source of new ATP to stay active. This is one of the major reasons we need to eat food in the first place — to replenish cells’ ATP.


    Glycolysis

    (Representation of Glycolysis)

    Now that we have pyruvate and ATP, we can move onto the third stage…
  3. The Citric Acid Cycle — Stage 3 of the breakdown of your food takes place entirely inside your cells, in a place called the “mitochondria.”

    There, the pyruvate we gained from the glycolysis step above, is converted into acetyl-CoA so it can be used in another important reaction called the “citric acid cycle.”

    The role of the citric acid cycle is to derive additional energy stored within the acetyl-CoA.

    Explaining all the details of the citric acid cycle is beyond the scope of this guide, but here’s a visual representation of the processes involved:

    Citric Acid Cycle

    The key point to remember in step 3 is that acetyl-CoA is used as an impetus to begin the citric acid cycle, which is needed to provide the majority of your cells’ energy so you can stay alive and functioning. (And, this is true whether or not you’re in ketosis.)

To summarize — when you consume a balanced diet of carbohydrates, fats, and proteins, food goes through three stages: 1) digestion, 2) glycolysis, and 3) the citric acid cycle.

Once these stages are completed, you have the energy you need to stay alive and keep moving!

Getting Energy from Food — While in Ketosis

Now, let’s look at the process of getting energy from food, but this time from the perspective of carbohydrates being restricted while following a ketosis-inducing diet:

  1. Digestion — While following a carbohydrate-restricted diet (such as keto), the body still digests food in the same manner as described while on a high-carbohydrate diet, so you won’t see many differences at this stage.

    As before, we are left with the following results of each macronutrient being broken down into these sub-units:

    Proteins ==> Amino Acids
    Carbohydrates ==> Sugars
    Fat ==> Glycerol
  2. Ketogenesis — As you know, the standard ketogenic diet has a different mix of proteins, carbs and fats compared to a “traditional” diet — as illustrated here:


    Traditional Macros vs Ketosis Macros

    While following a carbohydrate-restricting diet, your body cannot derive acetyl-CoA in its usual method (as described above in the section on glycolysis).

    Without glucose derived from carbohydrates, glycolysis cannot occur and therefore no acetyl-CoA can be derived from that process.

    However, since your body still requires acetyl-CoA to begin the vital citric acid cycle, it’s forced to adapt to a new energy pathway to begin the cycle.

    When glucose levels in your blood get low, your body looks to the next readily available source of energy, which are fatty acids and ketogenic amino acids.

    The biochemical process that your body uses to break down these fatty acids and ketogenic amino acids for energy is known as “ketogenesis.”

    Through ketogenesis, we derive new energy molecules known as “ketone bodies” — usually just referred to as “ketones” — through the process illustrated below:

    Ketogenesis Pathway

    (Ketogenesis pathway. The three ketone bodies — acetoacetate, acetone, and beta-hydroxybutyrate — are highlighted within the orange boxes.)


    These ketones allow us to free up energy stored in fatty acids, which are broken down using enzymes in a process called beta-oxidation.

    This process yields the acetyl-CoA which is needed to start the citric acid cycle.
  3. The Citric Acid Cycle — Once ketogenesis and beta-oxidation have produced the required acetyl-CoA, the citric acid cycle can continue to provide the body’s cells with energy, just as described in the previous example.

    Citric Acid Cycle

    (Citric Acid Cycle)

To summarize — the first and third steps of the two examples we described are virtually the same. It’s the middle step that differentiates the two:

  • In the example using a high-carbohydrate diet, acetyl-CoA is derived through glycolysis — which relies on the presence of carbohydrates.
  • In the carbohydrate-restricted example, acetyl-CoA is derived through ketogenesis — which utilizes stored fatty acids.

Either way — we end up at the same place — with acetyl-CoA being available for the citric-acid cycle. We just took different metabolic pathways to get there!

.

Macronutrients

The key to entering, and maintaining, a state of ketosis is properly balancing the specific macronutrients (“macros” for short) you consume each day. So, let’s make sure we start with a basic understanding of what we’re talking about when we use the word “macronutrient.”

The prefix “macro” means large or big and “nutrients” are those substances we eat to provide nourishment.

So, putting the two together, we can see that “macronutrients” means the things we eat each day in the largest amounts.

Wikipedia says this about macronutrients:

“There are three primary macronutrients: carbohydrate, protein, and lipids. Macronutrients are defined as a class of chemical compounds which humans consume in the largest quantities (must be above a threshold amount) and which provide humans with the bulk of energy.”

So, macronutrients are simply – proteins, fats and carbohydrates. (Wikipedia uses the word “lipids”, but we will use the more common term, “fats.”)

Proteins

What are Proteins?

You’ve probably heard that meats contain protein, or that bodybuilders take protein supplements to help build muscle.

But what exactly is protein? Proteins are macromolecules comprised of chains of organic compounds known as amino acids.

The order and position of the amino acids determine the differences between various proteins and their shape, which ultimately will determine the role each protein plays inside your body.



The Job of Proteins

Proteins are present in every cell of your body and perform a wide variety of functions, including replicating DNA, increasing rates of certain metabolic reactions, responding to stimuli and transporting molecules from one location to another.

Many types of proteins are involved in transmitting signals to cells in distant tissues while other proteins act as receptors that can intercept signals.

If you are injured, proteins help your cells repair. This is commonly experienced in muscle building when muscle fibers are broken down during strenuous activity and repaired during protein synthesis.

Protein can also provide your body with energy, yielding four calories per gram. With so many roles, you can see just how important proteins are!



Sources of Protein

As humans, our bodies naturally synthesize a certain number of amino acids which perform vital roles to keep us alive.

Other amino acids that cannot be synthesized in your body, known as essential amino acids, must be obtained from consuming foods containing protein.

Protein is found not only in meats, fish and poultry but also in foods like green peas, nuts, beans, and cheese.


Fats

What are Fats?

Fats are one of the three primary macronutrients and are comprised of chains of certain acids called fatty acids.

Fatty acids can be either saturated or non-saturated, which is where the terms “saturated fats” and “non-saturated fats” come from.

It’s interesting to note that the length of the fatty acid chain determines the consistency of different fats.

Fats comprised of long-chain fatty acids are solid at room temperature while fats made of shorter chain fatty acids are usually liquid at room temperature.

“Oil” is the term usually used to refer to fats that are liquid at normal room temperature while “fat” is usually used to refer to fats that are solids at normal room temperature.



The Job of Fats

Fats play numerous roles, all of which are important and essential to keeping your body running in tip-top shape. They are an essential part of any diet — ketogenic or otherwise.

In fact, certain vitamins cannot be absorbed without the presence of fat in the diet.

Vitamins A, D, E, and K are fat-soluble and therefore cannot function without adequate dietary fat. From keeping your eyes healthy to maintaining proper bone strength, these nutrients are an essential part of your daily diet.

Fats also provide the structural components of cells inside your brain, helping to build your brain while also insulating the nerve fibers that send messages.

Additionally, fats are responsible for creating and regulating several hormones.



Sources of Fats

Fats can be found in many foods and we described earlier that the length of the fatty acid chain determines whether the particular fat appears solid or liquid.

Common sources of fats, which will be familiar to everyone, are: peanut butter, nuts, olive oil, avocados, fatty fish (like salmon, tuna, or mackerel), soymilk, tofu, butter, cheeses, beef, lamb, pork, fried food, and some packaged snack foods (like chips, crackers, and buttered popcorn).


Carbohydrates

What are Carbohydrates?

Carbohydrates are molecules comprised of carbon (C), hydrogen (H) and oxygen (O) atoms.

In chemistry, carbohydrates are also known as saccharides, a group that includes sugars, starch, and cellulose.

Saccharides can be divided into four chemical groups which are monosaccharides, disaccharides, oligosaccharides, and polysaccharides. These different groups make up the various types of carbohydrates.

The word “saccharide” originates from an ancient Greek word that meant sugar.



The Job of Carbohydrates

Carbohydrates’ primary roles inside your body include energy and digestion. Most types of carbohydrates break down into glucose — the simplest form of carbohydrate and a source of energy for your body.

Carbohydrates that are not immediately consumed as energy are stored within your liver and muscles as glucose.



Sources of Carbohydrates

When you think about carbohydrates, most of you probably immediately conjure up images of pasta or bread.

While these certainly contain large amounts of carbohydrates, it may surprise you to learn that fruits and vegetables can also contain carbohydrates.

Bananas, berries, rice, yogurt, oatmeal, corn, sweet potatoes and even carrots are just a few foods you might not realize contain high amounts of carbohydrates.


Macronutrients for Ketosis

Most Americans get the majority of their daily calories from carbohydrates, which is not surprising given that the United States government has been recommending a high-carbohydrate diet for several decades.

Here is the most recent edition of the United States Department of Agriculture’s (USDA) Food Guide Pyramid:

Food Pyramid

Anyone following these guidelines would eat 6 to 11 servings of bread, cereal, rice and pasta (all loaded with carbs) and 2 to 4 servings of fruit (which also contain significant amounts of carbohydrates) each day.

Also, note the recommendation at the top of the pyramid to use fats “sparingly.”

Compare the macronutrient composition of the USDA’s recommended diet to the standard ketogenic diet and the differences will be very clear:

Traditional Macros vs Ketosis Macros

While fats are only 15% of the typical American diet, the keto diet recommends getting 75% of daily calories from healthy sources of fat. And, though carbohydrates make up about 55% of the USDA diet, they are only 5% of the ketogenic diet.

As we discuss in the Ketosis Explained section of this guide, it is the restriction of carbohydrates which causes the body to go into ketosis..

How to Get Into Ketosis

Getting into ketosis is relatively simple for most healthy individuals — just sufficiently restrict carbohydrate consumption until the body produces sufficient ketone bodies to be considered in ketosis.

While there are many different ways that people approach it (such as following the ketogenic diet, fasting, the Atkins Diet and the carnivore diet), ketosis really comes down to limiting carbs — in one way or another — long enough to deplete glucose reserves.

The time it takes to enter ketosis will vary, but research has shown it usually takes anywhere from 12 hours to several days for an individual to deplete their glucose reserves and transition into ketosis, once they have sufficiently restricted their carbohydrates.

It may also be possible to temporarily enter a mild state of ketosis by consuming enough ketones in the form of supplements, but the effect will be short-lived.

To stay in ketosis for an extended period, carbohydrates need to be sufficiently restricted through dietary strategies..

Ketosis Levels

Even though we may use the term “in ketosis,” ketosis isn’t really an all-or-nothing condition. It’s not like a switch is flipped from not being in ketosis to being in ketosis. There is a range of levels of being in ketosis.

Usually, someone is considered in ketosis when their ketone blood levels are over 0.5 mM (millimolar). There’s really nothing magical about that specific number, it’s just the ketone level most experts agree on for someone to be considered in ketosis.

(A quick explanation on measuring ketone blood levels — the measurement scale that’s used is called “millimolar” which is usually shortened to “mM.” The millimolar scale simply indicates how much of one substance is in another. In this case, it’s the level of ketone bodies in the blood. The higher the mM number, the more ketones in the blood.)

Several variables — such as how long and how severely you’ve restricted carbohydrates and your own personal biochemistry — will influence your level of ketosis.

For more information on ketosis levels, check out the section in this guide on Testing for Ketosis..

Testing — How to Know If You’re in Ketosis

Once you’ve become experienced transitioning into ketosis, you’ll usually develop a “feel” for when it happens.

One of the most common symptoms you may notice is something called “ketosis breath” or “keto breath,” which some describe as having a fruity smell. This change in breath is evidence of the body producing elevated levels of ketones and is a good clue that the individual is in ketosis.

However, if you want to determine objectively if you’re in ketosis and measure your levels of ketone bodies, there are three methods to use:

  1. Testing the urine using urine test strips
  2. Testing the breath using a breath meter
  3. Testing the blood using a blood test meter
Urine Testing Method

The urine test strip method is considered the least accurate way to test for ketone production but it’s quick, easy and relatively cheap.

Ketone/ketosis strips are narrow strips of paper specifically designed to identify ketones, particularly acetoacetic acid, in your urine. This acid reacts with a chemical in the strip to produce a color.

The color result on the keto strip will correspond with a chart which is usually found on the outside of the container your strips came in.

Here’s an example:

Ketosis Urine Strips

Typically, the strip will indicate higher levels of ketones with a deep purple color and lower levels of ketones with a peach color.

Ketone test strips can be purchased in most drugs stores and online for just a few dollars.

Breath Testing Method

Ketosis breath meters work by measuring the presence of a ketone byproduct called, “acetone” in the breath.

This method of testing for ketosis is considered more accurate than using urine test strips but not as accurate as the blood testing method. However, breath meters have the advantage of not having to deal with blood “pricking” (which some people are squeamish about) and that there’s nothing to replace in a breath meter — no supplies to buy for continual usage.

Breath meters are initially more expensive than urine strips (units average around $50) but should last long enough to make up for the higher initial investment.

Here’s an example:

Ketosis Breath Meter

Using a breath meter is easy — simply blow into the meter for the length of time recommended in the meter instructions and you’ll get a reading of your estimated blood ketone level.

Blood Testing Method

Blood testing is the most accurate of each of the three testing methods but it’s also the most expensive and potentially uncomfortable.

While the urine and breath test methods measure byproducts of ketone blood levels (acetoacetic acid in the urine and acetone in the breath) blood testing measures the actual levels of ketone bodies in your blood.

These meters usually cost more than breath meters and they rely on testing strips which have to be purchased for refill.

Blood testing meters use a small amount of blood — usually a couple drops — to determine ketone levels. There is a small amount of pain associated with drawing this blood which is a barrier to usage for some.

However, if you really want an accurate measure of your level of ketosis, the blood testing method is the gold standard.

Here’s an example of a blood testing kit (including lancets for drawing blood and ketone test strips):

Ketosis Blood Meter

Depending on your testing goals and budget, each of the three methods described have their place.

If you’re just interested in your approximate ketone levels and don’t want to spend much, urine test strips may be your choice. However, if you want more accuracy and are willing to spend more, then a breath or blood testing meter may be your best option..

Health Benefits of Ketosis

(Note — We do not claim you will experience any of the benefits mentioned here. Consult your healthcare provider before beginning a new diet or taking action based on any information provided here. Review our Medical Disclaimer here.)

With the dramatic increase in public interest in the keto diet, the scientific community has also become more interested in researching the possible benefits of ketosis on various conditions and diseases.

Worldwide, there are hundreds of ongoing studies related to ketosis-inducing diets and ketone supplements.

The European Journal of Clinical Nutrition (EJCN) conducted a review of therapeutic uses of very-low-carbohydrate diets (published by Nature Research here) saying, “Recent work over the last decade or so has provided evidence of the therapeutic potential of ketogenic diets in many pathological conditions, such as diabetes, polycystic ovary syndrome, acne, neurological diseases, cancer and the amelioration of respiratory and cardiovascular disease risk factors.”

Through their review, they looked at conditions for which they found evidence of possible therapeutic roles for very-low-carbohydrate diets and categorized those conditions as having either “strong evidence” or “emerging evidence” to support their use.

Here’s what they found…

Strong Evidence

These are conditions for which EJCN describes as having “strong evidence” for the “therapeutic roles of ketogenic diets:”

  • Weight loss (For more information, check out the Ketosis for Weight Loss section of this guide.)
  • Cardiovascular disease
  • Type 2 diabetes
  • Epilepsy
Emerging Evidence

These are conditions for which EJCN describes as having “emerging evidence” for the “therapeutic roles of ketogenic diets:”

  • Acne
  • Cancer
  • Polycystic Ovary Syndrome (PCOS)
  • Neurological diseases — including head ache, neurotrauma, Alzheimer’s and Parkinson’s disease, sleep disorders, brain cancer, autism and multiple sclerosis
  • Brain trauma
  • Amyotrophic Lateral Sclerosis (ALS)

(To keep up-to-date on the latest research developments, check out our Keto News section here.).

Ketosis for Weight Loss

While there may be several possible health benefits related to ketosis, it’s usually the desire to lose weight that first attracts someone to learn more about it.

Many people have found the ketogenic diet to be very effective for weight loss and this effectiveness is a big reason for the explosion of interest in keto over the last few years.

Often, keto dieters report that it’s much easier to eat fewer calories when following keto compared to other diets they’ve tried — sometimes without even trying.

High-fat foods tend to be very satiating — meaning they make us feel full — so eating a high-fat, ketogenic diet will often make an individual feel more full than someone eating the same number of calories derived from a higher-carbohydrate diet.

Besides feeling more full when eating a high-fat diet, there have also been some interesting scientific studies that show ketosis may actually affect the very hormones that make us feel full or hungry. Let’s look at that next…

Regulation of the Hunger Hormones

Whether we feel hungry or feel full is regulated by two hormones — leptin and ghrelin.

  1. Ghrelin, known as the “hunger hormone,” is responsible for our feelings of hunger. When our stomach is empty, more ghrelin is produced and when we’re full, that production subsides.
  2. Leptin has the opposite effect — it makes us feel less hungry.

These hormones work against each other and compete for the same receptors in the brain in a continual “tug of war” which results in us feeling either hungry or full. When ghrelin is winning the battle, we’re hungry. When it’s leptin in charge, we’re full.

It’s been shown that when we go on a diet and lose weight, our bodies tend to produce more ghrelin, which makes us hungrier and therefore more difficult to stay on our diet.

You may have experienced this yourself if you’ve gone on a diet. The more weight you lose, the more your body seems fight your efforts, by making you progressively more hungry. You can thank ghrelin for that.

An interesting study looked at the effects of a ketogenic diet on this process.

Researchers found that dieters following the ketogenic diet did not experience an increase in the hunger hormone as they lost weight.

Here’s what they said:

“When participants were ketotic, the weight loss induced increase in ghrelin was suppressed.”

Translated into simple English, when the dieters were in ketosis, they did not experience an increase in ghrelin as they lost more weight.

This is exactly the opposite of what most folks experience when they lose weight on a traditional (non-ketogenic) diet.

The researchers also found that:

“Ratings of appetite were lower at week 8 than after refeeding.”

Translating again — they found that the dieters said they were less hungry when they were on their 8th week of keto dieting than when they ate more food after they quit the diet!

You can read about this study yourself here..

Possible Side Effects of Ketosis

Any time we make a significant change in our diet, which has the potential to affect our health as much as going into ketosis, there’s always the possibility of side effects.

Many of these side effects are temporary as our body adapts from a glucose-based metabolism to utilizing ketone bodies for fuel.

In this section, we’ll discuss the most common side effects of going on a ketosis diet and some ways to avoid, or lessen, them.

(Note — Consult your healthcare provider before beginning a new diet or taking action based on any information provided here. Review our Medical Disclaimer here.)

Ketosis Flu

Ketosis Flu

Ketosis flu (or keto flu) is a commonly used term for a group of unpleasant symptoms some people — but not all — experience when they initially enter a state of ketosis.

While it’s not really the flu, and is not contagious, some reported symptoms are similar to the flu. These symptoms may include body aches, lethargy, disassociation, foggy-headedness and headaches.

If an individual experiences these symptoms, it’s typically during the first few days of transitioning into ketosis as the body depletes glucose reserves and gets used to burning ketones for fuel. After the initial adaptation phase these flu-like symptoms usually cease.

While these symptoms are not usually dangerous, they can be discouraging for someone who is pursuing a goal of entering, and maintaining, ketosis.

Common advice for lessening the severity and length of the ketosis flu includes:

  • Get adequate sleep
  • Drink plenty of fluids and stay well-hydrated
  • Ensure sufficient caloric intake — particularly healthy fats
  • Consider consuming additional electrolytes
  • Consider taking exogenous ketones, such as MCT oil
  • Slightly increase carbohydrate consumption (not enough to stop ketosis, however)

Not everyone experiences the keto flu when entering ketosis. And, many report that these symptoms are greatest the first time they enter ketosis and are much less severe, or even nonexistent, on subsequent transitions into ketosis.

For more information, check out our Guide to the Keto Flu here.


Ketosis and Constipation

Research has estimated that about 4 million Americans suffer from frequent constipation and it’s considered to be the most common digestive complaint in the United States.

Here are the most commonly suggested remedies for constipation:

  • Stay hydrated — Proper hydration is important for many reasons and is key to proper digestion.
  • Check your macros — Remember, the standard ketogenic diet is a high-fat diet, not a high-protein diet. If you’re experiencing constipation on keto, make sure you’re not overdoing it on protein consumption.
  • Get adequate fiber — So just how much fiber do you need? Recommendations are 30 to 38 grams a day for men and 25 grams a day for women between 18 and 50 years old, and 21 grams a day if a woman is 51 and older. Another general guideline is to get 14 grams of fiber for every 1,000 calories in your diet.
  • Increase physical movement and exercise.
  • Consider using digestive aids — When you switch over to a ketosis-inducing diet, you’re likely to start eating foods you haven’t eaten much of before — such as nuts and seeds. That change in eating habits may take your digestive system some time to get used to and many of these foods may be harder to digest. Digestive aids may be a useful, temporary option to help with improvement.

Ketosis and Headaches

Headaches are one of the most common complaints among American adults. However, if you are having more frequent, or more severe, headaches on a ketosis diet, it may be because of:

  • Ketosis flu — During the initial phase of transitioning to ketosis and until the body gets used to burning ketones for fuel, it’s not uncommon to experience what is called the ketosis flu. If you’re in the early stages of a ketogenic diet and are experiencing headaches, it may just be part of the process of your body adapting to being in ketosis. (Please review the Ketosis Flu section of this guide for suggestions to minimize the symptoms of the keto flu.)
  • Hydration — We mention the importance of adequate hydration in several sections of this guide — that’s because it’s so important. If you’re experiencing headaches, make sure you’re taking in adequate fluids.
  • Reduced caffeine intake — Along with starting a new diet, many folks make other lifestyle changes. A common change new dieters may make is to cut back, or even eliminate, caffeine from their diet. If you’ve reduced your caffeine intake along with starting a ketosis diet, it may be the caffeine withdrawal symptoms that are contributing to your headaches.

(Note — Consult your healthcare provider before beginning a new diet or taking action based on any information provided here. Review our Medical Disclaimer here.).

Ketosis vs. Ketoacidosis

Despite the two words sounding similar, “ketosis” and “ketoacidosis” are very different.

  • Ketosis is part of the body’s natural reaction to a reduction in available carbohydrates.
  • Ketoacidosis, however, is a potentially life-threatening condition which may require medical attention.


Ketoacidosis is most common in diabetics and, for that reason, the condition is often referred to as “Diabetic Ketoacidosis” or by the abbreviation “DKA.”

DKA may occur because of infections, not taking insulin correctly and even certain medications.

DKA results from a shortage of insulin and in response the body switches to burning fatty acids which produces acidic ketone bodies.

If the condition progresses, ketone levels may get extremely high — far beyond levels achieved by following a ketogenic diet — and the blood may become acidic, requiring medical attention.

Treatment for diabetic ketoacidosis usually involves insulin and fluids to combat the dehydration that often accompanies the condition.

For a healthy individual, there is little risk of ketoacidosis when pursuing ketosis by fasting or following a ketogenic diet..

(Note — Consult your healthcare provider before beginning a new diet or taking action based on any information provided here. Review our Medical Disclaimer here.)

Ketosis Pills & Supplements

With the increase in popularity of ketosis diets, there has also been a dramatic increase in the number of pills and supplements that companies are offering which they claim will help you with your efforts.

Unfortunately, when it comes to losing weight or improving health, there’s never a shortage of people trying to sell you a quick fix they claim will do all the work for you.

The ketosis-related pills and supplements we’ve reviewed fall into two categories:

  1. “Keto-friendly” supplements
  2. Exogenous ketone supplements

(“Exogenous” just means something you get from outside your body, so “exogenous ketones” are ketones you get from something you eat or drink, while the ketones your body makes are called “endogenous” ketones.)

“Keto Friendly” Foods & Supplements

“Keto-friendly” is a broad term that can mean many different things.

There are many companies trying to jump on the keto bandwagon, so we’re seeing foods and supplements that have been around for a long time, suddenly adding the words “keto-friendly” to their labels and advertising to take advantage of the excitement around keto.

Usually, by claiming something is “keto-friendly”, they mean it has a low carbohydrate content. However, there are no specific government or industry requirements that go along with using the term “keto friendly.”

Anyone can put that label on anything, so our advice is to carefully review the ingredient list of any product you plan to take or eat, before you buy it.

Just because someone claims their product is “keto-friendly” doesn’t mean it is, or that it will work within your diet. Always do your own research!

Exogenous Ketone Supplements

There are supplements that claim to contain exogenous ketone bodies — most often beta-hydroxybutyrate.

These supplements may be useful for you in the following situations:

  • To speed up your transition into ketosis — If you’re starting a ketogenic diet, it can take several days for your body to transition from glycolysis into ketosis. Exogenous ketones may help during that transition.
  • To attempt to deepen your level of ketosis — If you’re already into ketosis but want to raise the level of ketones in your blood, supplements may be a good option.
  • To add ketones to your system without being in ketosis — Research has shown there may be benefits to having ketone bodies in your system. However, for those that don’t want to commit to a ketogenic diet and transition into ketosis, they may receive some benefits by taking ketone-containing supplements.


The most common ketone supplement is MCT oil. MCT stands for Medium Chain Triglyceride and MCT oil is often derived from coconut oil. Many of coconut oil’s claimed benefits have to do with its ketone content.

As we mentioned when considering keto-friendly items, make certain you do your research before purchasing ketone supplements. Ketone supplements tend to be fairly expensive, so you’ll want to make sure you’re really getting what you pay for.

Also, be wary of claims that a supplement will put you into ketosis while you’re still consuming a traditional level of carbohydrates. Even if a supplement of exogenous ketones can put you into ketosis, that effect is normally short-lived and you’ll be back out of ketosis once the ketones wear off.

A final caveat — ketone supplements are known for being tough on the digestive system. If you’re going to take them, we highly recommend you start with a small dose to see how you react and then gradually work up to the recommended dose..

Ketosis and Fasting

As we discussed earlier in this guide, entering ketosis is caused by restricting carbohydrates to the point where the body burns fatty acids to produce the ketone bodies it needs for fuel.

While this can be accomplished by following a ketogenic diet, it can also be achieved by a period of fasting.

After all, while fasting you’re also restricting the consumption of carbohydrates (along with the other macronutrients) and after a long enough period of doing so, the body will enter ketosis.

The obvious difference between the two approaches is that there’s a time limit to how long an individual can fast whereas a ketogenic diet can usually be maintained as long as the dieter desires.

There are many approaches to fasting but they all have in common some form of restricting calories. This can include complete abstinence from eating (or even drinking) for long periods of time, to so-called “intermittent fasting” or “time restricted eating” which involve alternating between periods of eating and fasting

Fasting in general, and intermittent fasting in particular, are experiencing a dramatic increase in interest. The following chart shows the trend of Google searches for the term “intermittent fasting” over the previous few years. It’s obvious that more and more people are interested in the possible health benefits of fasting.

Intermittent Fasting Google Trends

The time it takes to enter ketosis via fasting will vary by individual — just as with the ketogenic diet — but research has shown it will usually take anywhere from 12 hours to several days for the fasting individual to deplete their glucose reserves and transition into ketosis.

When starting a ketogenic-style diet (or restarting a ketogenic cycle), many people find it’s beneficial to start with a brief fast of 12 to 24 hours and then move to following keto. This may have the effect of “kick-starting” the process, making it easier to transition into ketosis..

Ketosis and Alcohol

A common question for those that are on, or considering starting, a ketogenic diet is, “Can I drink alcohol and stay in ketosis?”

The answer is, “yes,” it is possible to drink alcohol and maintain a state of ketosis. As long as the carbohydrate content of the drink doesn’t exceed the dieter’s threshold for carbohydrate consumption for that day, they should be able to maintain ketosis.

Because alcoholic drinks differ greatly in their carbohydrate and calorie content, the keto dieter will need to be careful and choose their drinks accordingly.

Clear alcohol, such as vodka, gin and whiskey contain negligible carbohydrates, so they are usually good choices for staying in ketosis.

While these liquors have zero carbs by themselves, you’ll need to be aware of the carbohydrate content of common mixers. Mixers, such as fruit juice, soda or tonic water, often contain a significant amount of carbohydrates which can easily “knock” you out of ketosis.

Here’s the estimated carbohydrate content of several popular mixed drinks:

Ketosis Mixed Drinks Chart

Most wines are relatively low in carbohydrates — with usually less than 5 grams — so a glass of wine is a relatively low-carbohydrate drink option.

Here is the estimated wine carbohydrate content of several types of wine:

Ketosis Wine Chart

Beer is potentially the worst choice to consume when trying to stay in ketosis.

While the lowest carb light beers only have around 5 grams of carbohydrates, premium and specialty beers can have 15 (or more) carbohydrate grams per bottle.

Here is the estimated carb content of several popular beers:

Ketosis Beer Chart


For a more in-depth look at alcohol and its effects while on the keto diet, please visit our Guide to Alcohol & Keto (including video) here.
.

Ketosis for Vegetarians & Vegans

Vegetarians and vegans sometimes believe that following a ketosis-promoting diet may not be compatible with their dietary choices.

This is often because of the mistaken belief that a ketosis diet requires a high consumption of protein, which can be more difficult to do as a vegetarian or vegan. But that’s not the case.

Ketosis only requires sufficient restriction of carbohydrate consumption which can usually be accomplished on a vegetarian or vegan diet.

While there may be individuals following a ketogenic diet that eat a lot of protein, that’s not the way the diet was originally designed. In its standard form, keto is high fat, moderate protein and low carbohydrate.

Since the majority of the traditional ketogenic dieter’s calories are obtained from fats, the ketosis vegetarian/vegan’s main concern will be finding enough acceptable sources of healthy, dietary fats.

Fortunately, there are many types of fats derived from non-animal sources. Avocados, olive oil, coconut oil and a wide variety of seeds and nuts (such as pistachios, almonds, sunflower seeds and pumpkin seeds) are all examples of non-animal sources of healthy, dietary fat.

Vegetarians who consume eggs and dairy have even more options. Hard cheeses, high fat cream, butter and eggs are all quality options for consumption on the keto diet.