Starting Intermittent Fasting on Keto [Guide]

  • Date: June 7, 2022
  • Time to read: 10 min.

Intermittent Fasting (IF) is a dieting method where you eat only during certain times of the day. IF can have fantastic results on its own, but when combined with the keto diet, the results can be phenomenal. If this is something that you think you may fancy having a go at, we’ve got the ultimate guide for you on getting started with intermittent fasting on keto.

There are a number of health benefits of intermittent fasting. In order to list the benefits of intermittent fasting on keto, we polled our community, these were the answers which we got back in no particular order.

Benefits of Intermittent Fasting

The benefits of intermittent fasting are numerous. Different people will get a different experience out of fasting. When intermittent fasting is combined with the keto diet, the results of both can be amplified, and some people feel unstoppable.

Some of the most common health benefits of keto and intermittent fasting include:

Fat Loss

As your body transitions to using fat for fuel (known as becoming fat adapted), your body will be burning through your fat stores (aka glucose stores). This is a process known as fat oxidation.

This reduces the amount of fat in the body and can be measured by tracking your fat percentage. Changing body composition is one of the key things we advocate tracking as a non-scale victory.

Body fat can be an indicative factor of overall health, lean body mass being preferable.

Muscle Definition

This links in with fat loss above. The more fat you lose from around your muscles, the more you will see the definition of your muscles.

This is why extended fasting is often used by bodybuilders, before a competition.

Rebuild Your Immune System

Extended fasting for 72 hours has been shown to have a significant impact on the immune system. It encourages the repair and renewal of cells that support the immune system.

Improved Heart Health

Studies have shown that combining the keto diet with intermittent fasting may improve heart health by improving ‘bad’ LDL cholesterol, amongst other things. 

Deeper Ketosis

Ketosis is when your body uses fat for energy instead of glucose, ketone levels increase the deeper into ketosis our body goes.

Entering into ketosis is what everybody eating a keto diet is seeking to achieve.

Deeper ketosis (and increased ketone production) brings with it its own list of health benefits, allowing the body to repair and regrow as well as better sleep and an increase in energy levels.

With more energy, people naturally feel more inclined to do things, including having an increased sex drive.

Check out this article for more on the benefits of ketosis.

Increased Autophagy

Autophagy is a process where cells degrade themselves through lysosomes. This process helps the cell recycle damaged proteins and organelles. The process of autophagy is essential for cellular homeostasis and survival.

This is just one of the many metabolic health benefits of intermittent fasting on keto.

Reducing Inflammation

Fasting helps reduce inflammation because it causes the body to release hormones such as glucagon, which reduces blood sugar levels. This leads to lower insulin levels, which decreases inflammation.

Resets Gut Microbiome

By fasting for 24 hours, or longer, our bodies begin to detoxify and cleanse themselves from toxins. When our gut microbiome is in balance, our guts will help us digest food easier, leading to less bloating and discomfort.

This also can have a knock-on effect of clearer skin

Mental Clarity

After your body cleanses itself of toxins, your mind has access to a cleaner bloodstream, which results in clearer thoughts, faster processing, better memory, and sharper senses as a whole.

Greater focus is one of per personal favorite side effects of the keto diet, which is only amplified with intermittent fasting.

When you have greater mental clarity, your stress levels naturally reduce as you can get through more tasks with efficiency, i.e. you are more productive.

Hormonal Balance

Extended fasting gives the body the time it needs to reset its hormonal balance. This can help with a whole host of issues such as mood, and skin condition.

Insulin and Leptin Rebalance

As with hormones above, the ‘rest’ that extended fasting gives your body allows your body time to reset its insulin and leptin levels. Insulin sensitivity improves, which can be good for those who suffer from health issues such as diabetes or other conditions that insulin resistance may be a side effect.

Improved Blood Pressure

Intermittent fasting has been shown to improve a number of metabolic markers in the body, blood pressure being one of these.

Weigh Loss

It is unsurprising that one of the outcomes of extended fasting for a period of time will lead to weight loss.

A study completed in 2019 concluded that people who underwent several periods of fasting over a year period lost significantly more body weight than those that did not.

Wow! that is quite a list of potential health improvements to be seen from combining intermittent fasting with the keto diet. Some studies have concluded that intermittent fasting has helped in reversing a number of different health conditions, but that is outside of the scope of this article.

Ultimately, the longer you fast for (within reason) the more your body will become a fat-burning machine as it goes deeper into ketosis.

You will reap different benefits the longer you fast. Check out our fasting timeline guide for more on this.

It will also assist you in understanding what type of fast you need to do in order to achieve the health goals you require.

We have more on the different types of intermittent fasting below, as well as how to go about getting started with these.

Also, we are well aware that there are a lot of acronyms and abbreviations that are specific to the world of intermittent fasting, bookmark or print out our keto intermittent fasting key terms guide.

You may also be interested in our keto terms and keto abbreviations guide.

Getting Started With Intermittent Fasting

The first step towards IF is to choose a specific time of the day to start your fast.

This could be anytime after breakfast or after your evening meal the night before.

I personally chose to start my fast after my evening meal – that way I’m full in the evening, and then am asleep for around 8 hours of my fast.

For me, mornings are really busy, running around getting out of the house, and then my first few hours at work are normally crazy busy. This means that fasting from my evening meal, through to lunchtime fits perfectly with my lifestyle.

You will have to assess what time periods work best for you.

So if you choose to do this, make sure you skip breakfast and then eat lunch. If you want to try this out, I recommend doing it for 2 weeks.

After two weeks, you will know how much energy you have and how well you are feeling. Then you can decide whether you want to continue with this diet or not.

Another thing to consider is how long you want to fast.

Some people like 12 hours of fasting while others prefer to fast for 16 hours. There are pros and cons to both options.

For example, some people find that they sleep better when they fast for longer periods of time.

On the other hand, some people find that their metabolism slows down when they fast for longer amounts of time.

As mentioned earlier, there are many benefits to intermittent fasting. One of them is weight loss.

Top Tips To Get You Started With Intermittent Fasting on Keto

How to Start Intermittent Fasting

The first thing you should do when starting intermittent fasting is to make sure that your body is prepared for this new lifestyle change.

This means that you should start eating less than 16 hours before going to bed and eat only during those 8 hours. The next step is to choose the right type of intermittent fasting.

To begin with, you should try one of the below with some suggested fasting/feeding time frames for you :

• 16/8 – Eat normally from 8am to 4pm and fast from 4pm to 8am.

• 18/6 – Eat normally from 6am to 2pm and fast from 2pm to 6am.

Both of these methods work well for most people. However, if you want to get started with intermittent fasting, then I recommend that you try the 18/6 method. It is easier to stick to because you don’t have to think about what time you’re going to eat. Also, you won’t feel hungry at night because you’ll be sleeping longer.

If you decide to go with the 18/6 method, then you should follow these steps:

  1. Start out with a small meal (like a salad) around 5pm.
  2. Eat dinner around 7pm.
  3. At 1pm the next day, eat a small meal.

Times can be altered to suit your personal circumstances. Also, please be mindful of what you eat when you break your fast. For more information on this, check out our guide on how to break a fast.

What you eat post fast will not have much impact if you are only fasting for short periods of time, however, as you move on to longer fasts, good habits will stand you in good stead.

Once you are comfortable with this you can move on to longer fasts such as 19/5 or 20/4.

I would suggest doing a couple of weeks each before moving into the next time period. An example is given in the table below. It may be that you want to up your fasting period by 30 minutes each week, as opposed to an hour every two weeks.

This is up to you to assess. we have done a keto intermittent fasting plan for you below

Two Weekly Intermittent Fasting Time Table

This intermittent fasting timetable will see you building your fasting period by an hour every other week.

Fasting Period (hours)Feeding Period (hours)How Long For? 
1682 weeks 
1772 weeks 
1862 weeks 
1952 weeks 
2042 weeks 
2132 weeks 
2222 weeks 

Weekly Intermittent Fasting Timetable

This intermittent fasting timetable will see you building your fasting period by 30 mins every week.

Fasting Period (hours)Feeding Period (hours)How Long For? 
1681 week
16.57.51 week
1771 week
17.56.51 week
1861 week
18.55.51 week
1951 week
19.54.51 week
2041 week
20.53.51 week
2131 week
21.52.51 week
2221 week

These timings are not prescriptive, and you will find your own way through. There will be times when you can’t stick to your intermittent fasting schedule, family and friends will have events you will be expected to go to.

Don’t worry, just ensure that your meal sicks to the keto macros principles and then you can fall back onto your fasting plan.

Also, it’s important to listen to your body when fasting, as well as intermittent fasting on keto.

It may be that you are comfortable with a fasting period of 18/6 and you do not want to go any further than this. That’s ok too. the beauty with keto is that you can make it work for you in order for you to reach your keto goals.

Getting Started With Intermittent Fasting And Keto: Intermediate Guide

One Meal A Day

Once you are comfortable with the basics of intermittent fasting and you have mastered the above, you may want to consider eating one meal a day (OMAD).

OMAD stands for ‘One Meal A Day’, sometimes people will refer to this as one meal per day. The concept of this is simple, you only eat one meal a day. If you have already mastered 20/2 fasting, you are more or less doing this already.

For more on OMAD, we have a guide, on what is OMAD on keto.

Alternate Day Fasting

From here, you may want to try Alternate Day Fasting (ADF)

Alternate day fasting comes under the broader heading of ‘intermittent fasting’. It is one of the different takes on this concept.

For more information on fasting check out our guide to intermittent fasting on keto.

It involves fasting for a period of 36 hours, followed by a feeding window of 8 hours.

Some people interpret ADF as not eating on one day and then eating on the next. We would advocate the 36 hours due to the health benefits that the body starts to see at 36 hours.

What Do You Eat During Your Feeding Window?

As always, for anybody eating a keto diet, high carbohydrate, starchy foods should be avoided. Your carb intake should remain within your keto macros as should your caloric intake. You do not need to consume any extra calories, just because you are eating a keto diet.

For more on the basics of keto, check out our keto diet for beginners guide.

What Can You Drink During Your Fasting Window?

In short, you can drink anything that does not impact your insulin resistance. In reality this is very few drinks and you are limited to;

  • Black coffee
  • Black tea
  • White tea
  • Green tea
  • Still Water
  • Sparkling water
  • Mineral water

Check out our article if you want to find out more on what to drink when intermittent fasting

What Intermittent Fasting is Not For

Medical Conditions

Consult with a medical professional, or registered healthcare provider before undertaking intermittent fasting on keto, or even if you are not combining intermittent fasting with keto.

Intermittent fasting is not particularly not advised for those with amenia.

Out Eat A Bad Diet

Intermittent fasting is not designed to be the solution to eating a bad diet. The idea is not that you go out on a weekend, binge eat junk food, and then fast at the beginning of the week to compensate.

The reality is that without eating good quality, nutrient-rich foods before a diet, your body will not have what it needs in order to keep you going through your fast.

Fasting following binge eating/ drinking will be extremely difficult.

Can Athletes IF?

Yes, athletes can use intermittent fasting, and studies have shown that it can actually improve athletic performance.

Just get a meal plan and a fasting plan together that supports your athletic and IF goals, i.e muscle loss, muscle gain, improved performance etc. 

As well as athletes, there are a number of celebrities who swear by IF. Just Google and you will see for yourself that there is a whole hose of amazing success stories out there for people who have combined keto with IF.

As you will have seen from the above, getting started with intermittent fasting on keto has no end of potential benefits, and it does not have to be daunting. Follow our step by step guide to ease yourself into the work of IF.

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