One of the most common questions I hear from those just starting a Keto Diet is “How long does it take to get into Ketosis?” Here is the short answer:
When starting a Ketogenic Diet it takes two to seven days to get into ketosis for most people. People who are used to eating lower-carb diets get into ketosis faster, while those who relied upon carbohydrates as a diet staple will take longer. By adding fasting and more fat, most people can get into ketosis faster.
Now let’s dive into the details about getting into ketosis faster.
- Defining “Achieving Ketosis”
- How you can achieve ketosis faster
- What to do if it takes you longer to get into ketosis.
- How to know if you’re in ketosis.
The Details About How Long It Take to Get into Ketosis?
Let’s start with the ketogenic basics.
A ketogenic diet (Keto Diet) is a way of eating that promotes fat-burning and weight loss, can improve your mental clarity and mental health, and even treat diseases like epilepsy and diabetes, among many others.
When your body has made the transition to burning fat for fuel and is producing ketones, this is referred to as being in ketosis.
How long it takes to achieve a state of ketosis can vary depending on a number of factors, and we can speed up how long it takes to get into ketosis.
When your body runs out of glucose, it will switch to using fat as its primary source of energy and ketones as the main fuel source for the brain.
This transition is called moving from a state of glycolysis to a state of ketosis. If you want a more complete understanding of ketosis and the keto diet, here is a great in-depth keto beginners resource.
A Modern Definition of ‘Achieving Ketosis’
Achieving Ketosis – Verb – When your body has made the transition to burning fat for fuel and is producing ketones, this is referred to as achieving the state of ketosis (as opposed to the state of glycolysis where your body primarily burns glucose/carbs/sugar as fuel).
Achieving Ketosis is usually identified by detecting the presence of ketones (a byproduct of ketosis) in your urine or blood. More on this later.
How to get into Ketosis Faster
If you are asking how long it takes to get into ketosis, then you are also probably also interested in achieving ketosis more quickly.
So, How many days to get into Ketosis?
A generally healthy person who is committed to a Keto Diet lifestyle change can normally get into ketosis in two days.
Coming from a Standard American Diet (SAD) of high carbohydrates, your liver has the ability to store roughly two days’ worth of glucose in the form of glycogen.
Your body’s two-day supply of glycogen sets the normal minimum time to get into ketosis.
The best way to achieve ketosis quickly is by fasting for 24 to 48 hours. With the complete absence of carbs (and food), your body will burn through its glycogen stores in roughly 48 hours and will make the transition to ketosis.
P.S. Once you get into ketosis, Intermittent Fasting is often used as the secret sauce to losing weight effortlessly. Here are two resources to help you understand Intermittent Fasting: 1) The Rules of Intermittent Fasting here on my website. 2) Common Intermittent Fasting Mistakes here on my website.
How to get into Ketosis in three to seven days
If a full day or two of fasting isn’t for you, you can still achieve ketosis quickly.
If you are a relatively healthy person and begin eating a strict keto diet, keep your carb intake under 20 net grams and around 5% of your total calories, you’ll most likely get into ketosis within seven days.
To speed up the process of getting into ketosis, consider adding Intermittent Fasting to your eating style.
This daily 12 to 16-hour period without eating (8 hours of that you’ll be asleep) will encourage your body to become better at burning fat for fuel.
Some people take longer to get into ketosis.
If you have been very reliant on carbs for your entire life, and if you have other health issues, it could take much longer to see measurable ketones using any of the below ketosis measurement tools.
Before you begin a Keto Diet or any major change in diet or exercise, you should consult your medical professional to find out if you have any conditions that would make it more difficult or even dangerous to change your lifestyle in such a fundamental manner.
While there have been reports of people taking up to a month to get into ketosis, we believe cases like these are rare outliers.
If you are one who has taken a long time to get into ketosis, or perhaps you still haven’t achieved ketosis, it may be that your body is struggling with underlying health issues and needs a little help with the transition to such a big change in diet. Maybe you should consider a longer but more gentle way to get into ketosis.
Now you know how long it takes most people to get into ketosis, but how will you know when you personally have achieved ketosis? Read on…
When your body burns fat as fuel, it first converts that fat into ketones. You will use the presence of those ketones to know how long it took you to get into ketosis. We can detect those ketones in three ways using various tools. Each method to detect ketones is discussed below with affiliate links for your convenience.
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- Method. There are urine strips that you pee on and the color of the strip after a specific time will indicate your level of ketosis.
- Pros. Most pharmacies carry urine strips, and they come at a very affordable price. This is good for people who are just starting a ketogenic diet and want to know if they are in ketosis yet.
- Cons. Acetone is the first level of ketosis. Other types of ketones like AcAc (Acetoacetate) and BHB (Beta-Hydroxybutyrate) will not be detectable with urine strips anymore.
Method #2 for knowing if you have achieved Ketosis: Measure Ketones in Blood
This is a very accurate method of testing the ketone level in your body. The ketone BHB is transported through your blood, so this may be the most effective and accurate method to test your ketones.
- Method. Using a blood glucose meter, you use the lancet of the device and press it onto your finger to draw a little blood. The test strip monitor will show the levels of your ketones.
- Pros. This is by far the most accurate way to test your ketone levels, mainly because there are few factors that can alter the results.
- Cons. One strip can cost anywhere from $1-$10. It can be costly if you test frequently.
Method #3 for knowing if you are in Ketosis: Measure Ketones in Breath
This method is useful during the initial stages of ketosis. This is where the “fruity breath” of people who are new to reaching ketosis comes to light. This is the third method listed for a specific reason. It doesn’t seem very reliable. Following our commitment for complete honesty, we have never even tried a breath ketone meter, and we wouldn’t recommend anyone spend this much on a gadget that seems likely to disappoint. In our opinion, you should go with a blood meter if you want more accurate testing of ketones to know when you are in ketosis.
- Method. You can buy a ketone breath meter as a means to test the level of acetone you have in your body. This is not a very reliable method.
- Pros. Once you buy the meter, you can use it continuously without additional cost.
- Cons. It is not a very reliable method because only acetone can be easily detected by breath, and usually only early on in your ketogenic journey. Once again, this is a very expensive gadget that seems very likely to disappoint. To know if you are in ketosis, we recommend method one or two.
How to tell if you are in ketosis without testing.
While most of us on a Keto Diet want to test for ketones regularly, it is not necessary. Many times you can know if you are in ketosis by watching for signs and seeing the benefits. By watching for these ‘symptoms’ of ketosis, you’ll have a pretty good idea when you have achieved ketosis and begun burning ketones as your body’s primary source of fuel.
What are the signs or symptoms of Ketosis?
- Weight Loss
- Suppressed Appetite
- Breath Smells Fruity
- Clearer Mind
- Changes in Sleep
- Changes in Energy
- Improved Blood Markers (lower triglycerides and higher HDL “good cholesterol”)
- Lower Blood Pressure
Starting a keto diet is a big transition for many people. Your body takes a little time to adjust. Stick with it, be patient with your body and yourself, and you’ll soon be feeling and seeing the benefits of a ketogenic diet!
Tell us how long it took you to get into Ketosis in the comments below!
Founder Advantage Meals
Angela earned her Master’s Degree in Holistic Nutrition 14 years ago and began her lifelong journey of nutrition and wellness learning. She began keto meal planning and cooking over a decade ago when she began working with local clients who were under the direct supervision of a medical doctor. Angela is the author of No Cook Keto, the easiest keto meal plan available.
Disclaimer: I am neither a licensed nutritionist nor a medical professional. I never prescribe diets. I only share my personal experiences and those of my clients for informational purposes only. Nutrition details are provided for informational purposes only, and should not be considered medical nutritional data. You should consult your medical professional before making any major changes in the way you eat