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Keto Adapted: Training Your Body to Burn Fat

What does it mean to get keto adapted?

To be fat or keto-adapted means you have developed the metabolic flexibility to seamlessly and efficiently utilize fat as your primary energy source.

Additionally, the liver has become efficient at converting fatty acids into ketones (Ketogenesis). Your mitochondria are also able to easily use the ketones as energy.

How long does it take to become fat adapted on a ketogenic diet?

The specific time of metabolic “fat adaptations” varies depending on your initial metabolic health. However, at least several weeks (3-6) are necessary to completely transition to optimal fat utilization.

What are the advantages of being fat adapted?

It gives you a huge advantage over the average person. You don’t have to worry about getting low blood sugar anymore. Your body can easily produce ketones as needed to fuel the body and brain, even without food.

Table of contents

This fat-adapted, super- human phenomena was most famously demonstrated in this study Owen et al. in 1967.

Keto-adapted patients were given 20 IU of insulin. The blood glucose of the fasted patients dropped to 1–2 mM, but they displayed zero hypoglycemic (low blood sugar) symptoms because the brain can efficiently use ketones for energy.

“Fat has the greatest caloric potential per unit weight and is readily expendable. 8-Hydroxybutyrate and acetoacetate utilization by the brain shows that fat products may even satisfy the central nervous system’s (brain) substrate requirement.”

Brain Metabolism during fasting

The ability to become fat-adapted is the key to Keto success?

The secret to the success of the Ketogenic Diet is its ability to change the way the human body fuels itself at the cellular level.

Most people are what are known as “sugar burners.

In other words, they have only used glucose as fuel for their entire adult life and probably haven’t used ketones since they were a baby.

Breastmilk is ketogenic (low carb) by nature. Most breastfed infants go in and out of ketosis for approximately the first 6 months of their life, or until they start drinking formula or eating baby food.

The macronutrient ratio of breast milk is 5.6% protein, 38.8% carbohydrate and 55.6% fat.

The average American gets approximately 75% of their calories from carbohydrates.

It’s actually quite amazing how the ketone-adaptation process works.

I will use a car engine carburetor as an example. You have two main types of internal combustion engines, gasoline-powered and diesel-powered and they will only function with the proper type of fuel.

Ribeye Steaks help you get fat adapted

Now, imagine having two separate carburetors on the same engine and the engine can use both gas or diesel as fuel. But, if you never put gas in it then the gasoline carburetor will get clogged up, corroded or the seals might dry out. When you do try to run gas in it, the engine might not run properly.

On the other hand, if you alternate gas and diesel in the engine it should be able to run seamlessly using both types of fuel without any problems.

Now think of the car engine as our mitochondria and the fuel as ketones (fat) and glucose (carbohydrates). See how it’s important to frequently and occasionally use both sources of fuel.

That’s is why following a keto-adapted diet is so important.

The Keto Diet puts the correct balance of fuel in your tank so you can use both ketones and glucose. To be able to easily use both ketones and glucose means you are metabolically flexible.

The ability to use fat AND glucose as energy will keep you from getting that uncomfortable hangry feeling.

If you do get “hangry” between meals you are probably not metabolically flexible. Your body just hasn’t developed the ability to use ketones.

We have evolved to use both glucose and ketones as energy. When we completely stop using ketones as our energy it creates a whole host of metabolic disorders such as type 2 diabetes, obesity, fatty liver disease, and others. It’s perfectly healthy to become fat-adapted and at least occasionally go into a state of ketosis.

Taking keto BHB or exogenous ketones is a great way to get fat adapted

Keto adapted would be a more descriptive term because consuming ketones, specifically Beta-Hydroxybutyrate (BHB) would quickly raise your blood ketone levels. This would be beneficial in the early stages of the ketogenic diet when your mitochondria are still trying to “learn” how to use ketones as energy. Here is a good review of exogenous ketones.

Eating keto-friendly nuts and drinking apple cider vinegar before and after a fast is a great way to get fat adapted.

There are a few drawbacks to the keto diet. One of them is the adjustment the body has to make to become keto-adapted. It’s only temporary, but in all honesty, it can be difficult for some for the first few weeks.

How to speed up keto-adaptation.

That’s the miracle of keto-adaptation, you can seamlessly run on fat or glucose. When you would normally get hungry and want a snack, your body just taps into your fat stores and you never feel the need to snack.

You can skip meals and Fast without any problem. The cravings for sweets and starches diminished greatly because you don’t suffer from drastic blood sugar spikes. Another benefit (see chart below), when following a Ketogenic Diet, when you exercise, you burn significantly more fat.

When you are fat-adapted and break your keto diet by eating too many carbohydrates, it is much faster to get back into ketosis. When the average “sugar burner ” starts a ketogenic diet or wants to start intermittent fasting, he can struggle. On average it can take anywhere from 48 to 96 hours before he can actually get into ketosis.

A fat-adapted individual can usually get back into ketosis in 24 hours.

Fat oxidation increases with fat adaptation

The human Mitochondria are tiny little organelles that are the engines of the cells. They convert calories from food to the molecule adenosine triphosphate (ATP). The mitochondria can use either carbohydrates/glucose or fatty acids/ketones as energy.

Glucose yields 36 ATP molecules, and fat yields 48 ATP molecules inside the mitochondria. So our bodies and brains get more efficient energy from fat/ketones.

Understanding keto-adaptation.

Fat adaptation, also known as becoming keto-adapted is the process by which your body has become accustomed to burning fat for fuel instead of carbohydrates/glucose.

Since we have lived our entire life using glucose as energy, our mitochondria have lost the ability to efficiently use fat as fuel.

That’s why we get “hangry” between meals and feel like we need to snack. Your body runs out of glucose and expects to get more. When it doesn’t get the expected glucose it sends danger signals to your brain. The addiction to sugar is directly related to the euphoria involved in blood sugar spikes.

That’s the key to fat-adaptation on the Ketogenic diet

You restrict your carbohydrate intake drastically and you trick your body into thinking it’s starving. Since you are eating a high-fat diet, your body senses the extra fat and is forced to use it as fuel.

Your body always wants to burn glucose before fat, so you keep the glucose low and force it to burn fat. Just like anything, the more you do it, the better your body gets at it.

You actually “train” your mitochondria how to burn fat and they become efficient at it. You recalibrate your metabolic machinery. This “fat adaptation” includes robust metabolic and enzymatic adaptations.

Being fat adapted means eating and living in a state where you enjoy the benefits of using fats and ketones as your preferred source of energy.

Ketones have been the primary source of fuel for the human species (hunter/gatherer) for the last approximately 2 million years.

It’s only been about 7000 years ago that we start eating grains. And it’s only been since about the 1950s that we have adopted such a high refined sugar/carbohydrate processed foods diet. Getting fat-adapted is the secret sauce to lowering blood sugar, insulin and putting type 2 diabetes in remission.

Fixing your digestive health will also help your body adapt to keto

*When you are increasing your fat intake make sure to eat more good fats and less bad fats. Beware of Lazy Keto.

Why You Need to Get Fat Adapted (Video)

There are very limited studies on the fat-adaptation process on human subjects. However, in a low carbohydrate environment, after prolonged exercise, a small amount of muscle glycogen synthesis occurs. This is due to hepatic (liver) gluconeogenesis which is a source of glucose for glycogen.

How long does it take to become keto adapted?

“Horses supplemented with fat after exercise showed impaired glycogen synthesis, but 3 weeks of a high-fat diet resulted in similar glycogen repletion as horses fed a high-carbohydrate diet.”

Fundamentals of glycogen metabolism
Bob Murray and Christine Rosenbloom
In Mark Sisson’s book “The Keto Reset Diet” he talks about resetting your metabolism in 21 days.
“We show for the first time that chronic keto-adaptation in elite ultra-endurance athletes is associated with a robust capacity to increase fat oxidation during exercise while maintaining normal skeletal muscle glycogen concentrations.”

How does being fat-adapted benefit you?

When you become keto-adapted from consistently eating a ketogenic diet (including intermittent fasting), the body cannot anticipate its next meal. So, instead of breaking down protein to maintain blood glucose, metabolism shifts to conserve blood glucose and to spare protein by increasing fatty acid oxidation and the increased production of ketone bodies.

Here is a very interesting study that shows that restricting carbohydrates can mimic the benefit of actual fasting. So when we Fast and follow a Ketogenic Diet between our fasting period, we can continue reaping some of the benefits even after our fast is complete.

Low glucose equals low insulin, and in the absence of insulin, mobilization of free fatty acids from adipose tissue (fat) continues to increase.

Ketogenesis produces ketone bodies (acetoacetate and β-hydroxybutyrate) and they are metabolized to acetyl-CoA and used for energy production by many tissues (muscle, brain, kidney).

Acetone, a ketone formed spontaneously by decomposition of acetoacetate, is what gives you bad breath when you are in ketosis.

Once you become keto-adapted and if you do fall off the wagon, it’s much easier to get back into ketosis. You can generally get back into ketosis and start burning fat again within 24 hours.

This Keto-Adapted Diet Plan will give you some ideas of what to eat

Nuts, cheese, and pepperoni are a great snack to help you get fat adapted.

A fat-adapted diet should include plenty of keto-friendly nuts

The fat-adaptation phase of the Ketogenic Diet requires plenty of healthy fats to be consumed. This stimulates the body to use that fat as fuel.  Our bodies are very efficient, if all you are giving it is fat, the body will figure out how to convert it into energy (Ketogenesis).

Keto fans on our Ketogenicinfo Facebook Group consistently ask the question:

How to Speed up Keto Adaptation?

  • Workout in a fasted state
  • Take 1 tablespoon of extra virgin, cold-pressed olive oil
  • Take 1 MCT oil with cod liver oil
  • Eat 1/2 cup of macadamia nuts to break a fast
  • Eat avocados and pasture-raised eggs with salt
  • Drink 1 Keto Flu drink (tonic) daily
  • Go on a 3-day keto egg fast
  • Go on 48-hour water only fast
  • Take the weight loss supplement Forskolin during your fast
  • Put butter in your coffee and make a keto coffee

Try the Speed Keto plan to put you in a state of ketosis.

Keto Fat Adapted Signs:

How did this whole Keto-adapted thing get started?

A little History:

Most people think of Dr. Robert Atkins as the father of the Ketogenic diet. In 2002, the commercial success of the Atkins’ diet plan led Time Magazine to name the doctor one of the ten most influential people. Contrary to popular belief, he didn’t die of a heart attack. Dr. Atkins died on April 17, 2003, at the age of 72.

Nine days prior to his death, Atkins fell and hit his head on an icy New York sidewalk. But… there was someone long before Dr. Atkins:

Founding father of keto adaptation: Vilhjalmur Stefansson
Vilhjalmur Stefansson

In 1928, arctic explorer Vilhjalmur Stefansson professed the virtues of the Ketogenic diet. Of course, they didn’t call it the Ketogenic diet back then. Stefansson had been exposed to the diet after an extended stay in the Mackenzie Delta of the western Arctic in 1906.

When a ship carrying his supplies failed to materialize, he instead depended on the hospitality of a local family for food. At first, he struggled with the high fat, low carb diet. “When I got home I would nibble at it and write in my diary what a terrible time I was having,” Stefansson wrote later.

Keto adaptation is born

Stefansson gradually became fat-adapted to the boiled, frozen, and fermented fish that he was forced to eat. He primarily ate fish and meat from seals, whale, caribou, and waterfowl, and the short summers offered very few carbohydrates from the limited vegetation available.

HeVilhajalmur found that he and his fellow explorers were very healthy and had plenty of energy on such a diet. He lived in the arctic eating like that for four years! He discovered his body could function perfectly well, remain healthy, vigorous and slender. The keto-adapted arctic explorer ate only as much food as his body needed and never felt hungry.

When Stefansson returned to the USA there was widespread skepticism when he reported his findings of the virtues of high fat, mostly meat diet. At the request of researchers, Stefansson was asked to eat meat only as an experiment.

There were no deficiency problems during the experiment and he remained perfectly healthy. He ate an average of almost eighty percent of his energy from animal fat and almost twenty percent from protein.

His daily intake varied from 100-140 grams of protein, 200-300 grams of fat, and 7-12 grams of carbohydrates. Over the years, this research was largely ignored.

Don’t forget to put butter and MCT oil in your coffee or try Keto Coffee to help you get fat adapted quicker.

Here is a Keto diet Beginners Guide and a good keto diet shopping list to get you started.

Robert Bryant
Robert Bryant

Becoming fat adapted changed my life. No more being “hangry” and letting food control my life. I wanted to research and understand the science behind it and share what I’ve learned.


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