How Long Does it Take to Become Keto Adapted?

When people start the ketogenic diet, they tend to be a bit impatient about seeing results. Many of them question how long it takes to become keto-adapted. The frustrating answer is that it varies from person to person. However, the average time frame to become keto adapted is going to be 4-5 weeks.

Ketosis vs. Keto-Adapted

First and foremost, you should understand that there is a difference between simply being in ketosis and being keto-adapted.

First, let’s discuss the definition of ketosis. Ketosis is the state your body enters where it is producing its own ketones. There are three main ketone bodies that your body produces – acetoaccetate, acetone, and beta-hydroxybutyrate (BHB). Ketones are produce by the liver as a result of breaking down fatty acids.

There is a tiny problem with this simplified definition of ketosis. The liver is constantly breaking down fatty acids and creating ketones. However, we don’t consider people to constantly be in ketosis until the level of ketones produced is high enough. So how high do your ketone levels have to be considered “in ketosis”? Dr. Stephen Phinney, who is the one who actually coined the term “nutritional ketosis.” He provided a lower and upper limit to the definition of nutritional ketosis. By Phinney’s definition, nutritional ketosis is the state of ketone production that lies between 0.5 mmol/dl and 5 mmol/dl.

Once your body is producing ketones at a level between 0.5 mmol/dl and 5 mmol/dl, then you are in ketosis. You can be in ketosis easily when you wake up in the morning because you have been intermittent fasting for 12 hours, but you won’t necessarily be keto adapted.

Keto-adapted refers to a state where the body is using fat as its primary fuel source. Your body has to go through a few changes in order to become keto-adapted. First and foremost, you have to eliminate glucose and glycogen as an optimal fuel source. Then you have to produce ketones within the “nutritional ketosis” range. Finally, you have to produce ketones within the “nutritional ketosis” range long enough that your body switches to using fat as its preferred fuel source. Once that happens, you are keto-adapted.

Keto-adaptation can take a while because there is an interesting interplay between the energy needs of your brain and the skeletal muscles. When ketone levels are lowered, the muscles will use ketones for fuel. As the ketone levels increase, the muscles will burn fat for fuel instead. The brain uses ketones in proportion to the amount present in the blood. When you have more ketones in your blood, there will be more ketones for the brain to use and fewer ketones for the muscles to use. (The muscles start to use fat directly instead of ketones when this happens.

At a certain point, your muscles will be using your stored fat for fuel and your brain will be functioning on ketones for fuel. This is when you are keto-adapted.

So, when you get out those ketone strips to measure the ketones in your urine, realize that this is the first step to becoming keto-adapted. Keeping those ketone levels in the nutritional ketosis range for about 4-5 weeks will ensure that your body becomes keto-adapted.

What Can I Do to Help My Body Adapt?

One of the most important things when going through the adaptation phase is to ensure that you are getting enough salt according to Dr. Phinney. Your body is adjusting to a different fuel source and may be flushing out toxins and in the process eliminate some of the essential minerals in your body. You may want to consider an electrolyte powder.

Your body will adjust to being fat adapted in stages.

The First Three Days: Carbohydrate Withdrawal

Some people consider the first few days to be carbohydrate withdrawal. There are some common characteristics between addictions and excessive carbohydrate intake. For example, you may feel carb cravings simply because the diet you are used to has so many carbohydrates and your body is adjusting.

You may also feel a period of discomfort when you first cut back from carbohydrates. This is mostly psychological. You are missing your favorite high-carb foods. Many people find that they think about the foods more once they are gone.

To get over this hurdle, there are some things that you can do:

  1. Consume Fiber with Fats. When you combine fat with fiber, it produces a feeling of satiety. You will feel full. Often when you have a feeling of being full, you stop thinking about food if you engage yourself in other activities. Salads with a high fat dressing, celery and dips and nuts can give you a feeling of satiety while staying on a low carbohydrate diet.
  2. Stay Full! The ketogenic diet is not about restricting calories. You should not go for long periods of time feeling hungry and thinking about forbidden foods. Plan three meals per day. If you find that you are hungry in between, plan a few low-carb snacks. This can relieve food cravings as you become keto-adapted.
  3. Drink Plenty of Water. Staying hydrated is one of the most beneficial things that you can do for your body. As it is going through this transition of relying on carbohydrates to fats for fuel, it will help to have water on hand.
  4. Get Support. Switching to a low carbohydrate diet can be very challenging. I have found it extremely helpful to join online support groups and understand that my experience is not unusual. A good support system will help to cheer you on when you want to quit.

Days 3 to 5: Watch Out for Your “Carb Crash”

People who have been consuming a high carbohydrate diet sometimes experience what is known as a “carb crash” a few days into a very low-carb diet. The theory behind this is that your body’s glucose reserves (stored as glycogen) are used up, but your body isn’t used to running on fat and protein, or being keto-adapted, yet.

The carb crash symptoms include feeling shaky, feeling irritable, feeling fatigued, and not feeling right. This phase is temporary and will go away in a few days. During this time, most people increase their electrolytes to counter the symptoms. Some people include a few low carbohydrate fruits, such as strawberries and blueberries to alleviate some symptoms. However, this is not an excuse to overload on the carbs. That defeats the purpose. Just add in a few extra berries if the carb crash is an issue for you.

Days 5 to 14: Rewards!

If you’ve made it to the end of your first week on the ketogenic diet, you should start to see some of the rewards of your low-carb dieting. This is the point where people begin to experience increased energy, improved mental concentration, less compulsive eating and a reduction in carb cravings. For some, it is as though a fog has lifted that they didn’t realize was there.

Each person’s experience is different and it will take longer for some than others. Everyone starts at a different level of health. However, if you are someone who is sensitive to carbs, you will likely feel the benefits from this way of eating quickly. The first week is the most challenging, so congratulate yourself for taking the first steps toward a positive change.

Other Keto-Adaptation Changes

Ketogenic diets and other low carbohydrate diets, such as Atkins, have been shown to reverse signs of metabolic syndrome, polycystic ovarian syndrome, type 2 diabetes and seizure disorders. Research is even showing that ketogenic diets can help with other neurological conditions such as Alzheimer’s and Parkinson’s disease.

The ketogenic diet has also demonstrated that it reduces inflammation in the body. Using ketones for energy may decrease the oxidative stress on the body that causes inflammation. This will reduce the symptoms of chronic diseases.

9 thoughts on “How Long Does it Take to Become Keto Adapted?”

  1. Hello Melinda,
    Very informative and interesting post, I have gone through your previous post also and I love all of them. I will keep following you for a healthy life.

    Thanks for sharing it.

  2. Hi Melinda,

    If I go on this keto way of eating the body will use body fat to fuel itself and that is it? Never heard of keto before at all. Don’t suppose you have a typical keto food list if I wanted to begin this?

    I read somewhere that there were side effects and that there is a time period for this. However, the article seemed glib and they did NOT tell me how long does it take to become keto adapted – I found that information here so I am very happy, along with much more details to boot!

    ;4 to 5 weeks is not so long when you consider the health benefits of such a diet. Its too easy to be accustomed with the processed rubbish that is actively altering our DNA from the stores. All these food programs on TV and they never tell you that either. Nor about the sprays that are bad for us either. I am into growing my own food and so its possible to grow such foods for the keto plan?

    Great article and it is definitely food for thought – HAHA – sorry, could not help myself. It was a pun begging to happen…

    By the way, that dish in your article looks delicious!

    – Philip.

  3. Hey Melinda
    The more I read your posts the more I get convinced to start a keto diet.
    The reason is because you give the most valuable information for living with a keto diet in the market. This article has shown me that it is possible to be keto adaptive for anyone.

    Thanx a lot

  4. I have done a ketogenic diet a few times in my life. Every time I get something that’s referred to as the “keto flu”. I feel fatigued and can’t think straight. On my last go I found out MCT oil really helps with this. I think it produces ketones faster than your body can convert the from your fat stores which is one of the reasons you get the flu. You’re out of glycogen but not producing enough ketones yet. Feel free to correct me if I’m wrong with this!

    These days I’m eating a more carb based diet with intermittent fasting. I have almost stopped eating meat and milk products due to ethical and ecological reasons and it’s pretty hard to do keto and have a balanced nutrition as a borderline vegan. Thanks for the great write up!

  5. What an interesting article. How easy is it to live to this diet long term? Is it meant to be a long term lifestyle diet? I can truly believe people would feel much better cutting out carbs but how does this diet work if you do a lot of exercise. I know there are loads of vegan out there that run marathons etc but what would be the alternative to cutting out carbs?

    1. Actually, once you are keto-adapted, or fat adapted, you can run marathons with plenty of stamina. I have a friend who does them and he follows a keto diet!
      I don’t personally recommend that vegans go keto. There are some people who do it and rely on a lot of coconut oils and avocados. There are some online resources for vegan ketogenic dieters though.

  6. Hey Melinda,

    This is such an informative guide to starting a keto diet. I haven’t tried before myself as I was usually unsure how to but now I feel much more confident in trying something new, especially when its so healthy for the body.

    Thanks for taking time to write this!


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