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Keto Adaptation – What You Need to Know

Keto Adaptation is one of the most difficult parts of the diet. And, If you want to experience any of the major benefits of the ketogenic diet, you’re unfortunately going to have to first make it through this rocky period. It could take a few weeks to a few months to get completely there. But, once you do, it’s ALL worth it! Keto is amazing, and when you are fully adapted you’ll understand FIRST HAND all the reasons why it is. Before we get into it – I want to remind you what sits on the other side of adaptation… This is WHY we do keto!

The Awesome Benefits of Keto
  • Leaner Physique
  • Better blood pressure
  • Better mood
  • Better insulin sensitivity
  • Lower Risk of Cancer
  • Lower Risk of Type II Diabetes
  • Increased Cognitive Function

What does it mean to be keto adapted?

Keto adaptation is the process by which organs in the body begin selecting fat over sugar as the primary fuel source. These organs include both our brain and muscle tissue. The adaptation process only begins after a person abstains from carbohydrates for a period of time.

When someone is adapted, there are a number of indicators that point to the body efficiently using fat for energy.


The first major indicator that you are fat adapted is that carb and sugar cravings fly out the window. In contrast to that, after Initially starting the diet, the body is going to be dependent on carbohydrates and thus you’ll be craving those types of foods for a little while. A quick thing to note – If you are craving carbs, your body is essentially telling you that you are NOT fat adapted. As you continuously limit carbs, your cravings will change in favor of fats. [1]


After adaptation, the body becomes much more insulin sensitive. Some studies have suggested that insulin sensitivity improves by as much as 75% through the Ketogenic diet. [2]

Blood Pressure

Blood pressure normally drops after entering into ketosis and should continue to remain at lower levels after fat adaptation. Since insulin levels will drop during ketosis, the excess water and sodium retention attributed with a high carb diet and high insulin levels, will diminish. It’s astonishing how much blood pressure can actually drop through keto adaptation. [3]

Blood Ketone Levels

Entering into the range between .5 mM to 3mM blood ketone reading (beta hydroxybutyrate) indicates that a person is in nutritional ketosis. This is a prerequisite  to becoming fat adapted. I’ll get more into this later, but just understand that you can’t become fat adapted until you’ve FIRST gotten yourself into this dietary ketosis range. Keto blood test strips are the most reliable way to check to see if you are in ketosis. I would recommend the KETO-MOJO Blood Ketone and Glucose Testing Meter Kit if you aren’t already testing your blood. This isn’t something you NEED to do but it can definitely be helpful for determining when you should be making adjustments in your diet. For example, do you know how many grams of carbs and protein your body can normally tolerate per day to stay above a .5 mM blood ketone reading? If not, these kits can be very helpful in determining when you need to switch things up. The investment is worth it for simply that knowledge alone. Once you figure this out, you shouldn’t need to keep testing regularly.

Fat Burning Changes

One interesting benefit of fat adaptation is that the body oxidizes fat for energy much faster – especially saturated fats (butter, cheese, red meat). This leaves us with less saturated fats in the blood stream. Your body is going to be cleaning that stuff out and burning it up for energy.

The bottom line is that when our metabolism adapts to a low carbohydrate diet, saturated fats become a preferred fuel for the body, and their levels in blood and tissue triglyceride pools actually drop.

-Dr Jeff Volek and Dr Stephen Phinney (The Art and Science of Low Carbohydrate Living)

Energy Efficiency – Brain and Muscles

As for your brain and muscles – they become really good at shuffling ketones between each other for energy. As they adjust to not having carbs, your muscles begin to favor a specific ketone for consumption which is acetoacetate. This is one of TWO ketones produced in the liver and it becomes the main energy source for fat adapted muscles. In the muscle, acetoacetate is then broken down into beta-hydroxybutyrate. The interesting thing is that your BRAIN favors beta-hydroxybutyrate over acetoacetate. What happens next is that your body becomes REALLY good at moving ketone types from one organ to another. There is little waste.

When you are keto adapted you’ll see MORE beta-hydroxybutyrate in blood circulation and LESS acetoacetate. But, In the beginning, it just the opposite. The urine strips will be picking up lots of excess acetoacetate. As you stick to the diet, that will “peter out” because the preferred muscle ketone changes. This is why a lot of people say the strips aren’t very accurate. But, the fact of the matter is that your body is just going through fat adaptation.

Reduced Free Radicals

It is known that the metabolism of carbohydrates can cause inflammation. Carbs are a “dirty” energy source. As inflammation causing free radicals are produced, they damage cell membranes which ultimately lead to higher insulin resistance in your muscles. As you become fat adapted, cell mitochondria do not produce these free radicals. Essential Fatty Acids (Omega 3’s) stay at healthy levels within our cells. This makes fat a very “clean” burning energy source. [6]

How long does it take to adapt?

It can take as little as 2 to 3 weeks but as long as 2 to 3 MONTHS to adapt. Complete metabolic adaption to the ketogenic diet takes about 6 weeks. By metabolic, I mean your body’s efficiency with burning fat. You can be producing ketones, BUT at the same time be not so great at using them for energy.

In general – It is best if you slowly transition into the diet versus trying to make a sudden switch (at least in regards to protein). Try to transition into lower than 50 carbs over the course of a week and slightly increase your protein intake to start. One reason for this has to do with your muscles and their energy preference. When you first start restricting carbohydrates, your body is actually going to need more protein to maintain muscle composition. This is because your body, at this point in time, still prefers to burn sugar. And, since you’ve stopped eating sugar and carbs it’s going to try and get that sugar from your MUSCLES (gluconeogenesis) instead of choosing fat like you would expect.

But, even still… if you decide to just quit carbs cold turkey and drastically lower protein, no worries you’ll be fine. You’ll actually get adapted faster this way. You could experience more keto flu symptoms, but they will pass in time.  Just keep in mind… the beginning is the period in time where you would want to consume a bit more protein to prevent muscle wasting. Taper the protein down as you become increasingly adapted over the next few weeks. Continue to cut carbs going down to 20g to 30g per day if you can.

Metabolic Changes

It isn’t until after we restrict carbohydrates for a few weeks that the liver actively and consistently produces ketones. It was observed that competitive triathletes didn’t get back to their baseline performance until after about 6 weeks (at which point they were fully adapted). [5]

As I mentioned earlier about how it takes time for the body to actually start favoring fats, you’ll want to stay in ketosis for as long as you can to help adaptation complete. You NOT ONLY need to be in ketosis beforehand, but the mitochondria of your cells ALSO need time to adapt while IN ketosis. The body will be increasing the rate at which it is able to burn fats – particularly saturated fats. It gets good at burning fats by being forced to burn fats. Practice makes perfect!

When you are going through the adaptation phase, it is VERY important to stay in ketosis. Don’t cheat!  If your body gets over 50 grams of carbs per day, it is going to have no reason to switch it’s fuel source so this process could take longer. On top of that, once you exit ketosis it will take several days to get back to where you were. Even one day can throw you off track!

Digestive Changes

Your liver and gall bladder need to adjust for more efficient fat digestion. That doesn’t happen overnight. Your liver will be ramping up on bile production and the gall bladder will be storing the bile to then release into the intestine as you consume more fats.  In addition, the pancreas also needs to undergo adaptation in order to produce more digestive enzymes for fat breakdown. [4] To aid with fat adaptation, keep your liver, gall bladder, and pancreas in healthy condition. They all work together. If you have had digestive issues in the past, consider supplementing with bile salts. Bile salts are a big component here and your body should also be producing them naturally. They assist with breaking larger fat molecules into smaller ones for your body to digest.  And, since fats are not water soluble, bile salts aid with solubilizing them. I am a fan of Dr Berg’s brand.

How do I adapt faster?

The key thing to remember here is that you need to be in Ketosis in order for fat adaptation to take place. There are many organs in the body that need to adjust to fat adaptation, not just your brain and muscles.  Being in ketosis is a prerequisite to becoming fat adapted.

Stick to the Diet

Do not fall out of ketosis! If you do, even for one day, the adaptation process will be lengthened. Try to go for 3 weeks at a minimum at .5 mM blood ketone level. Your goal here is going to be to stay in ketosis for about 3 weeks. This diet does not work well with hopping in and out of carb world. After you are adapted, you’ll more easily transition back into ketosis and preferred fat burning mode. But, until then… you need to stick to the diet! If you DO happen to drop out of ketosis, be easy on yourself. I’m not perfect either and things are going to happen. Just get back on your horse right away and keto on!

Intermittent Fasting

Intermittent fasting is great for getting you into ketosis quickly. If you are intermittent fasting every day, you can at least be confident that most of your day is being spent in some level of ketosis. This is also great for your digestive system.

Lower the Carbs

Keep your carbs extremely low. The lower your carbs the faster your body is going to have to adjust to fat burning. It will have no choice but to burn fat.


Eat MCT fats. They bypass the liver and are immediately passed into the blood stream. MCTs can pass the blood brain barrier and can also enter cell mitochondria without the help of Carnitine. [1] This means that you’re going to be feeling better all around in terms of energy.

Lower Your Workout Intensity

If you are trying to adapt for the first time, it may be best to avoid high intensity workouts during your first 1-2 weeks.  During an intense workout, your body will not be very efficient at fueling you well with fat. It may even try pulling sugar from your muscles resulting in a rise in blood sugar (which would obviously knock you out of ketosis.) This isn’t to say that you CAN’T do this, but you’ll likely be feeling more weak during this time as is. The last thing you want to do is get frustrated and give up on the diet. The strength and endurance will come.

How do I know I am keto adapted?

When it comes to the effects of being adapted, these benefits are generally observed with most people. Not having all of them does NOT NECESSARILY mean you aren’t adapted. This is just a guiding list to see how well you are doing.

  • Increased performance when working out at your capacity
  • Consistent energy levels throughout the day
  • Fat loss while maintaining lean muscle mass
  • No sugar or carb cravings (instead you will be craving fats)
  • Lower blood pressure levels
  • Better mood
  • Not “hangry” when skipping meals
  • Keto Flu Symptoms have disappeared.

Why is it so important to stay in ketosis?

I’d like to conclude with a few words of warning – the body does very well with fat after it has time to adjust to burning fat exclusively. But, one of the key things to know is that the body is NOT so efficient at switching back and forth between carbohydrates and fat – especially if you haven’t allowed for an extended period of fat adaptation. If you are going to follow keto, stick with it or just don’t do it. The more you walk the line, the more trouble you are going to have. So, try to stay in ketosis or you could experiencing some of these things…

  • You might never become adapted metabolically.
  • Your body might try to convert muscle to sugar more often.
  • Energy and fatigue will be a problem.
  • The benefits of ketosis can be lost in hours but can take 3 to 7 days to get them back.


[5] – “Chapter 12.” The Art and Science of Low Carbohydrate Living: an Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable, by Jeff Volek and Stephen D. Phinney, Beyond Obesity, 2011.

[6] – “Chapter 9.” The Art and Science of Low Carbohydrate Living: an Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable, by Jeff Volek and Stephen D. Phinney, Beyond Obesity, 2011.

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