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How Long Does It Take To Get Into Ketosis? [Real Case Study]

A self experiment to see how long it takes to get into ketosis. Find out how long it took me along with best practices to reach ketosis as quick as possible.

Chances are, you landed here because you’re considering a ketogenic diet or maybe you’ve even started your ketogenic journey. Usually, the first question people ask when considering a ketogenic diet is:

A. What is ketosis?

B. How long does it take to get into ketosis?

How long does it take to get into ketosis? How long it takes to get into ketosis can vary from individual to individual, but it will take on average between 24 and 72 hours.

Just like I always say about almost everything… IT DEPENDS, but we’ll get into the nitty-gritty along with tips and tricks to get you there as quick as possible.

So hold your horses.

how long does it take to get into ketosis pinterest cover

When you enter a state of ketosis, your body switches its primary fuel source from using glucose (sugar) to using FAT, most notably ketones and free fatty acids. This has been associated with many health benefits including:

  • Reduced hunger and increased satiety
  • Increased and steady energy levels
  • Decreased inflammation

So just how long does it take to get into ketosis and experience these wonderful benefits?

How Long Does It Take To Get Into Ketosis

 It’s been my experience that we can achieve ketosis, producing ketones, possibly within just a day or two of fasting or ketogenic dieting…  but, I figured I would show you how long it took to get into ketosis rather than just telling you how long it does.

How long it takes to get into ketosis – the experiment.

This led me to run an experiment on myself to answer that very question.To do so, I couldn’t already be in a state of ketosis.

Therefore, part one of the equation was knocking myself out of ketosis. I accomplished this by doing exactly what you’re thinking, I ATE CARBOHYDRATES! In fact, I ate just shy over 500g of carbohydrates a day for over 4 weeks.

Why so many and for so long?

Part of the reason I ate so many carbohydrates was that my calorie intake was around ~3500 calories. Since my fat intake was kept relatively low (~75g a day) the only way to get my calories up to that level was to increase carbohydrates and/or protein.

Why not just eat carbohydrates for a day or two?

They say it takes about 3 to 4 weeks to become “keto-adapted,” basically when you become efficient at utilizing fat/ketones and experiencing most of the benefits of ketosis. I decided to do the opposite, but with carbohydrates, and take the same amount of time to revert back to becoming primarily a sugar burner.

And just maybe this was my excuse to eat tons of rice and cereal for a month.

Just kidding.

OK, kind of kidding.

Once you’ve been fat adapted for so long, it’s a lot easier for your body to dip in and out of ketosis. I wanted to kind of hit the “reset button,” and make sure I was starting without an advantage for lack of a better term. 

Below is a typical breakdown of my macros over the four-week period.

~3500 calories 500g of carbohydrates, 200g of protein, 75g of fat

A typical day during the experiment

There you have it, this was my typical intake for over four weeks before this experiment. It’s almost impossible for me to be in a state of ketosis given the sheer amount of carbohydrates I’ve been consuming.

Before getting started, I will be defining entering a state of ketosis as registering .5 mmol/L or higher on the blood ketone meter.

It was Dr. Stephen Phinney and Dr. Jeff Volek whom coined the term “nutritional ketosis,” which is a ketone production that lies between 0.5 mmol/L and 5 mmol/L. So that’s the definition I will use.

how long does it take to get into ketosis ketone chart

Day 1

I’m confident I’m not into ketosis, so I decided to hold out and not test until the evening of day 1. Below is a picture of my blood ketone reading via my keto mojo. Obviously, I am far from being in ketosis! So here then begins the journey.

how long does it take to get into ketosis day 1

Activity for day 1

I didn’t want to do anything out of the ordinary, so I decided not to work out at all today (even though that would be ordinary for me). However, I do aim for a minimum step count each day and ended my day with around 11k steps.

Macro breakdown for day 1

I decided to kickstart the process a bit while also giving my digestive system a break. I did fast for all of day 1 and didn’t have anything except coffee and water until breakfast the next morning.

What I failed to mention was that I ended my last carb day with a good amount of pizza and a very hefty serving of ice cream 😉

Day 2

Well, looks like I’m still not technically in nutritional ketosis territory, but at least I’m registering something vs. just getting a “LOW” reading. It may only say 0.1, but I’ll take it!

A little progress

7am – 9am

On the morning of day two, I did go to the gym for a light workout with weights. I had some coffee before working out mixed with some C8 Oil, grass-fed butter, and a scoop of whey protein.

10am – 2pm

Post-workout I had one of my standard go-to meals of 12oz ground beef with half an avocado and two hard-boiled eggs. About 4 hours or so later I had the same meal… I’m boring, what can I say?

But what do you know, before eating my final meal of the evening it looks as if I am already hitting a mild level of ketosis. This is about 36 hours after consuming about 800 – 900g of carbohydrates.

I could have possibly been registering above .5 mmol/L earlier, but I didn’t test my ketone levels again until I returned home in the evening around 5:30pm.

So, if I were to assume I was starting hitting mild levels of ketosis around this time, it puts me at about ~40 hours after my last carbohydrate-filled meal.

There you have it, it takes precisely 27.231091 hours to get into ketosis.

Just kidding. Like anything, results will vary by individual. It may take as little as a day for one person while it may take four or five days for another. Things that may influence how fast or slow you get into ketosis include:

  • Your previous diet before starting
  • Your activity levels
  • Lifestyle (Stress, sleep, etc.)
  • Carbohydrate intake

But the truth is, it really doesn’t matter how long it takes you to get into ketosis. You have to realize that it’s a lifestyle and how fast you get into ketosis is irrelevant in the big scheme of things.

 What really matters is how consistent you will be over the LONG TERM? Ketosis or not. 

That said, how many days to ketosis will vary from person to person, but there are ways to speed up the transition that we’ll go over below. I just wanted to show you first-hand how long it took me to give you a baseline.

How To Get Into Ketosis Fast As Possible

I know I said it doesn’t matter how fast you get into ketosis, but there’s always those who don’t care or just want to know LOL…  So, the section below is just for you.

7 Tips to get into ketosis quicker

Just like my self-experiment, we will define ketosis as reaching a level of .5mmol/L or above via a blood ketone reading.

My preferred blood ketone meter: keto mojo

how long does it take to get into ketosis 7 tips on how to get into ketosis in 24 hours

Eliminate carbohydrates

We already know we have to limit carbohydrates on a ketogenic diet severely. How many carbs that is will vary by individual and is usually dictated by one's activity levels.

The general carb limit for a ketogenic diet is around 30 net grams per day. [footnote]Net grams are total carbohydrates minus any fiber and/or sugar alcohols.[/footnote] Take this a step further and reduce your carbs to 30 grams or less of TOTAL carbohydrates.

Intermittent fasting

Fasting is often used in combination with keto by many individuals. By prolonging the time in which you eat your first meal, you begin to deplete the body of readily available glucose and stored glycogen.

An easy way to implement intermittent fasting is merely to skip breakfast. A popular intermittent fasting protocol many people start with is a 16:8 fasting to eating window.

In short, don’t eat for 16 hours and eat all your calories within an 8-hour eating window. In practice, this might look like eating all your meals between noon and 8pm.

Drink coffee

Ok, coffee won’t really help speed things along, but it should help out with curbing your appetite, and that’s important for any diet. It’s also a great way to help ease into intermittent fasting if you’re giving that a go.

Low-intensity exercise

Low-intensity exercise, such as walking or light cardio, can help speed things along in the beginning.

People often confuse depleting muscle glycogen (which happens with high-intensity exercise) with achieving ketosis, but it’s when liver glycogen gets low enough that it starts producing ketones as a new source of energy.

Definitely one of many pieces of misinformation I see being spread. Not to say that you shouldn’t do any high-intensity exercise, but for the sake of getting into ketosis faster, it’s not required.


Medium chain triglycerides are one of the quickest sources of energy we can use on a ketogenic diet, especially at the onset. MCT’s are easily absorbed and transported throughout the body since it travels straight from the gut to the liver.

MCT’s can also help suppress hunger and provide quick, clean energy, especially for the brain. Just be careful and start with a low dose before going all in… or you may find yourself scurrying to the bathroom.

  • My favorite MCT Oil.
  • My favorite C8 Oil.

C8 Oil (caprylic acid) is a form of MCT Oil, but C8 converts explicitly to ketones much quicker. I also find C8 oil a bit easier on the stomach. The one drawback is it is slightly more expensive than straight MCT Oil.

Increase fat intake

At the beginning of your keto journey, I usually recommend keeping fat intake up. We don’t want to cut calories drastically at the beginning, and we must replace those calories that were once filled with carbohydrates with healthy fats.

You can accomplish this easily by eating fattier cuts of meats, whole eggs, and including fat sources like avocados and nuts.

There’s often another misconception that to enter a state of ketosis that you must eat a high-fat diet. Truth is, the only requirement to enter a state of ketosis is a reduction/elimination of carbohydrates.

Exogenous ketones

Taking exogenous ketones can possibly help decrease the amount of time it takes to reach a state of ketosis. Another benefit is that taking exogenous ketones can almost act as a buffer in helping avoid common side effects while transitioning to a ketogenic diet.

Basically, it can help avoid the dreaded “keto flu.”

My favorite Exogenous Ketones supplement.

Ok, but what is the absolute FASTEST way to get into ketosis if you had to pick one?

How To Get Into Ketosis In 24 Hours

That’s an easy one.


 Fasting to get into ketosis is literally the fastest way to get into ketosis. 

As mentioned previously, when liver glycogen is depleted, the liver will start producing ketones. The easiest way to get rid of liver glycogen is not to eat combined with a bit of low-intensity exercise like walking.

How Many Hours To Get Into Ketosis?

If you're up to the challenge and want to exercise your way into ketosis, no matter the pain you must endure, this may interest you.

In this study, liver glycogen stores were substantially depleted within ~90 minutes of moderate to high-intensity exercise.1 

If you've run a marathon or know someone who has, you may have heard the term “bonking” or “hitting the wall.” These terms describe the sudden onset of fatigue and loss of energy you may experience.

From first-hand experience, it's not a great feeling. Your legs feel like cement, you get a bit dizzy, and continuing to run is the last thing your body wants to do.

Liver and muscle glycogen are both severely depleted. 

It's not uncommon to be producing ketones by the end of a marathon run, even by those not following a ketogenic diet.

Additional Tips While Transitioning Into Ketosis

Stay hydrated

People often experience rapid initial weight loss at the beginning of a ketogenic diet. Most of this weight loss in the first few days is due to water loss. For each gram of carbohydrate, your body carries with it a good ~3-4 grams of water.

Plus, staying hydrated can help keep you from overeating since many people sometimes mistake hunger for thirst. Aim for four to five clear urinations per day as a good general rule of thumb.

Increase electrolytes

Increasing electrolytes goes hand in hand with staying hydrated, most notably sodium. Aside from reducing carbohydrates, when most people switch to a ketogenic diet, they are also eliminating a lot of pre-packaged foods that were high in sodium.

Double whammy.

A lot of the side effects such as the keto flu can be mitigated or significantly reduced just by drinking more water and increasing electrolytes. Don’t be shy and salt your food to taste.

Get enough sleep

It always surprises me how much people don’t pay attention to sleep. Proper sleep is vital for hormone function, and it’s the time our body repairs itself from the stresses of everyday life.

Try to aim for a solid 7-8 hours of sleep each and every night.

How Can You Tell If You Are In Ketosis?

There are three primary methods to test your ketone levels:


Probably the most accessible and most affordable method, but also the most inaccurate and messy of the three.

You can likely find ketosis sticks at your local pharmacy or order them online via the link below.


More accurate than urine testing, breath testing measures acetone being exhaled on your breath. You can measure the level of acetone on your breath using a breath monitor, such as a Ketonix or LEVL meter.

The upfront cost of a breath meter is the highest of the three, but you don’t really have to repurchase test strips or pee on sticks making it cost-effective over time and probably the least messy of the three.


The most accurate way to test whether you are in ketosis and what I’ve been referring to previously in my experiment. Testing for blood ketones is the same way someone with diabetes would check their blood sugar levels.

The drawback to a blood ketone meter is it can get expensive purchasing the ketone test strips over time. Also, if you have an aversion to blood, it might not be the best option.

I recommend the keto mojo blood ketone meter as they offer the cheapest ketone test strips at 99 cents each. The test strips also require the least amount of blood compared to that of their competitor.

how long does it take to get into ketosis how to test your ketone levels

And the fourth method…

But you said there’s three?

The fourth way is subjective as it doesn’t require an actual test to measure your ketone levels.

Instead, if you don’t have access to a blood, urine or breath ketone test OR just don’t want to test then you can use the below signs and symptoms to gauge whether you may be in a state of ketosis.

But of course, you won’t REALLY know unless you test.

Increased focus

When you are in ketosis, your brain switches its primary fuel source from carbohydrates to ketones. You might start to notice a marked increase in mental clarity and less brain fog than before.

Decreased hunger

Ketosis has been shown to affect both satiety and hunger. Basically, satiety and hunger are two of the most critical aspects that cause people to quit their diets.

This may be another reason why a ketogenic diet is the preferred form of dieting for weight loss for many individuals.

Increased energy

When you’re in ketosis, you tend to suffer less from energy swings as you have a constant supply of fat for energy, both from your body and from your diet.

Compared to that of a carbohydrate-based diet where insulin and energy levels tend to spike and dip in relation to a meal.

Keto breath

In the beginning, many people report a slightly sweet smell coming from their breath. Better yet, their friends and family start to report the smell since you probably won’t notice it on yourself at first if you’re not paying attention.

Since acetone is expelled via your breath, you may notice your breath smells like that of nail polish. I find this smell usually goes away after a few weeks on a ketogenic diet.

Reasons Why You May Not Be In Ketosis

how long does it take to get into ketosis reasons you may not become keto adapted

You’re eating too many carbs

Sometimes people simply underestimate how many carbohydrates they are actually consuming (along with calories in general).

They also try to see just how far they can push their net carbohydrate consumption and have a tag along of 100 grams of sugar alcohols and fiber from “keto friendly” protein bars and other miscellaneous snacks.


If you’re not eating these keto friendly snacks filled with sugar alcohols and prebiotic fibers… there’s a slight chance you may be eating something with enough carbohydrates to keep you out of ketosis.

Your best bet is to track your food intake, and be honest because you’re fooling nobody but yourself if you’re not.

You have too much stress in your life

There’s a reason they say stress is the silent killer. Below are 9 ways to help eliminate or at least lower your stress levels.

For myself, meditation and a gratitude journal have been a game changer. Personally, I use the headspace app for meditation every morning along with the five-minute journal.

You're pretty sedentary

I’ve personally found that those who combine a mix of low-intensity exercise and strength training not only get into ketosis faster but have exponentially more significant results. 

Nobody says you have to become a bodybuilder, but I firmly believe everyone should be including some form of resistance training and trying to stay active when possible.

A great way to get in more activity is to use a fitness tracker like a Fitbit. Start small and work your way up. A great goal is to aim for 10,000 steps a day but don’t let me stop you there.

If you're still stuck wondering why you're not in ketosis, I wrote an entire article all about it.

Getting Into Ketosis Quickly: The Takeaway

Hopefully, you’ve followed along from my self-experiment to the tips on how to get into ketosis faster. If you skipped everything just to read the summary, then shame on you! Go back up and obtain some edu mi cation.

There are some things that I listed above that might seem obvious, but sometimes it takes hearing it from someone else before we actually start implementing it.

In short, how many days to get into ketosis will vary from person to person, but in general, you can expect to reach a nutritional level of ketosis between one and four days for most individuals.

If you are looking to get into ketosis at lightning speed for some reason, then fasting to get into ketosis is the FASTEST way to get into ketosis.

Tips on how to get into ketosis fast include:

  • Utilizee intermittent fasting
  • Eliminate carbohydrates even more or completely
  • Drink coffee / consuming caffeine
  • Use MCT Oil and/or exogenous ketones
  • Incorporate low-intensity exercise
  • Increase your fat intake

And to really close it out.

I just want to reiterate that your goal shouldn’t be to get into ketosis as fast as possible. What you should really focus on is how to make ketosis more than a diet, but a lifestyle that you can sustain over the long term.

Would love to hear your thoughts or maybe if a lightbulb went off. Simply let me know in the comments down below.

Founder of The Art Of Keto.

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