Will A 24 Hour Fast Put Me In Ketosis? [+TOP TIPS]

  • Date: June 8, 2022
  • Time to read: 7 min.

Will a 24 hour fast put me in ketosis? If you’re asking this, I’m guessing you’re making the move into the world of fasting and are seeking to get all of the health benefits from ketosis too. Here we will take you through everything you need to know about, fasting, keto, and how to get into ketosis fast. Don’t skip our top tips on how to get into ketosis FAST!

Ketosis And The Keto Diet

If you’ve landed on our little corner of the internet, you’re probably interested in the keto diet.

One of the main goals of keto is to get into the metabolic state known as ketosis. In this article, we will take you through what ketosis is, whether you are able to get into ketosis in 24 hours, and what the health benefits of this are.

Finally, we will take you through our top tips for getting into ketosis in 24 hours, to try and help you on your way.

Ketosis In Brief

Ketosis is when your body uses fat for energy instead of carbohydrates. This state occurs naturally after fasting, or when you eat very few carbohydrates (sugar). At this stage, your blood sugar levels will have started to decrease.

When you are in ketosis, your body burns fat for fuel rather than carbs.

When we enter ketosis, ketones are produced by the body.

Ketones are molecules produced when fat is broken down for energy. When we eat carbohydrates, our bodies break them down into glucose which is then used for energy. But when we don’t eat carbs, our bodies use stored fats instead.

To find out more about ketosis check out our article which will take you through everything you need to know including what ketosis is and how to know if you are in ketosis.

If keto as a whole is new to you, check out our keto for beginners guide.

Intermittent Fasting Combined With Keto 

If you are already eating a keto diet, adding intermittent fasting combined with this can have some amazing health benefits.

Getting into ketosis is just the beginning of that.

So, lets get onto answer the question, will a 24 hours fast put me in ketosis?

Will A 24 Hour Fast Put Me In Ketosis?

Below we will take you through all of the different stages of fasting, as you will see, if you have been fasting for around 12-14 hours, your body will start producing ketones.

It is only after 48 hours that your ketone levels will have increased and your level of ketosis will deepen.

So getting into deep ketosis within 24 hours is going to be a challenge.

There are other factors that will affect how quickly you can get into ketosis, which we will discuss below. 

Stages of Fasting

4-6 Hours  –  Blood Glucose Drops

10-12 Hours  –  Liver Glycogen Used

12-14 Hours  –  Rise In Ketones (Ketosis begins)

18-20 Hours  –  Fat Oxidation Increases

22-24 Hours  –  Liver Glycogen Depletion

24 Hours  –  Gluconeogenesis Progresses

24-36 Hours  –  Growth Hormone (HGH) Spike

36-48 Hours  –  Autophagy Increases

48-72 Hours  –  Ketosis Deepens

Day 3  –  Gluconeogenesis Peaks

Check out our article on the intermittent fasting timeline to find out about the different health benefits that you can achieve after different periods of fasting. It should also help you decide whether starting off with a 24 hour fast is for you.

Factors Affecting How Quickly You Can Get Into Ketosis

Whether a 24 hour fast will put you into ketosis will depend on a number of different factors. We have listed these for you below.

Factors Which Will Affect How Quickly You Get Into Ketosis

There are a number of factors that will affect how quickly you can get into ketosis including all of the below.

  • Age
  • Carb Intake
  • Fat Intake
  • Protein Intake
  • Exercise Level
  • Alcohol Consumption
  • Metabolism
  • Health issues

Carb consumption is going to be the biggest factor for the majority in this. If you have already been in ketosis and have been eating a keto diet for a long period of time, and you have dropped out of ketosis for any reason, you MAY be able to get back into ketosis within 24 hours.

The same is true if you have been eating a low-carb diet for a long period of time.

However, if you have been eating a high-carb diet for years, you are going to struggle to get into ketosis within 24 hours.

As you will see from the timeline above, and if you have read our beginner’s guide to keto, you will be aware that the first stage of getting into ketosis is that the body needs to burn through (metabolize) all of the glucose stores in the body.

If you have been eating a high carb diet for years, you are likely to have a bigger backlog of glucose stored in your body to work through. Therefore, it is likely to take longer to get into ketosis.

Exercise is the second factor that is likely to affect most people in trying to get into ketosis. If you are a regular carb eater, and exerciser, you are likely to have fewer carbs stored in your body than somebody who does not exercise.

If you are a regular exerciser, you may be in a better position to get into ketosis within your 24 hour window.

What Is Your Motivation For Getting Into Ketosis Quickly?

If you are asking the question, ‘Will a 24 hour fast put me in ketosis?’, I am guessing that you are falling into one of the below categories;

Keen to get started on keto – If this is the case, that is amazing, but keto is a way of life and not a ‘quick fix’

Fallen off the keto wagon or had a ‘cheat day’ – If you have had a cheat day, and you’re looking to get back into ketosis quickly. If this is the case, fasting is not the answer to your issue. Spend a couple of days ensuring that you eat your keto macros before trying to fast.

This will ensure that your body has all of the right nutrients in it in order to sustain your fast and for your body to continue to function properly without shutting down some of its functions.

Have consumed your body weight in alcohol carbs – Hand’s up – I’ve been there. There is no judgment at all. However, alcohol will slow down the fasting process. So if you are looking to get back into ketosis quickly, fasting is not going to be your answer.

Check out our ultimate guide for drinking on keto for our top tips on enjoying a drink and not getting kicked out of ketosis.

Rather than starting out with a 24 hour fast, why not check out our guide to intermittent fasting, which will talk you through how to build up to a 24 hour fast.

That way you can combine all of the health benefits of the keto diet, with all of the metabolic benefits of intermittent fasting.

TOP TIPS For Getting Into Ketosis Fast

Based on all of the above here are our top tips for getting into ketosis fast;

  1. Reduce your carbs for the days running up to your fast
  2. Ensure you are well hydrated before and during your fast
  3. Do not drink anything during your fast which would raise your insulin levels. Check out our guide for more on what to drink during a fast
  4. If you can, exercise. If you have a smart watch or anything, you will likely be used to seeing when you are in the different ‘zones’ of training. In order to start burning through your carbs at an accelerated rate, you need to be in the ‘fat burning’ zone. I know this seems counterintuitive when you are trying to burn through glucose (carbs), but that is where you need to be. Intense exercise is going to burn through your glucose stores, which will help you achieve your goal of ketosis within 24 hours.

How Do I know If I am In Ketosis [Testing Ketones]

You can test your blood, breath, or urine in order to know whether you are in ketosis or not.

Urine strips are cheaper and easier to use, but will not give you an accurate reading as to how many ketones are in your bloodstream, as these are only measuring the ketones which are leaving the body. Also, ketones will show up in your urine sometime after they are in your blood.

So if you are testing to see how quickly you have managed to get into ketosis as quickly as possible, you may want to test your blood.

Therefore a blood ketone meter may be a better option for you. This will let you know whether you have reached your goal of getting into ketosis within 24 hours.

Don’t Undo All Of Your Hard Work

How you break your fast is key to not undoing all of the hard work you have just done in the last 24 hours. 

Do not suddenly eat a big meal that is high in carbs, as this is going to undo all of your good work and kick you out of ketosis.

Ease yourself back into eating food and ensure that the foods are low in carbs in order to keep you in ketosis. As long as you stick to your macros from here on, you should remain in ketosis.

Fasting Warning

If you are considering fasting and you are on any medications or have any health issues, please seek medical advice before undertaking any fast.

If you are planning on fasting for 72 hours or longer, please seek medical advice, as fasts of this duration should only be conducted under the supervision of a health care professional. If in ANY DOUBT, please seek medical advice first.

Let Us Know

Have you gotten into ketosis in 24 hours? Let us know what your experience was. Do you have any top tips to help us?

If you have mastered 24 hour fasting, why not try OMAD?

So, Will A 24 Hour Fast Put Me In Ketosis?

There are so many factors that will affect you getting into ketosis within 24 hours that it is impossible to say whether you will be able to get into ketosis within 24 hours or not. Why not have a go and let us know your results in the comments below.

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