Intermittent Fasting on Keto: What to Know Before Combining the Two

The keto diet and intermittent fasting are two diet practices often done together due to their powerful benefits. If you’re here because you want to know if you should try it, we’ve got the answers you seek.

Read until the end of this article to know the definition of each, how intermittent fasting on keto works, and any risks to be aware of.

What is the Keto Diet?

The ketogenic diet, or the keto diet for short, is a very low-carbohydrate diet. It works this way: Lower your carb intake to 20-50 grams per day. Meanwhile, increase your fat and keep protein moderate.

By depriving your body of carbs, its usual energy source, it enters ketosis. This is a normal metabolic state in which your body utilizes its fat stores for fuel. Many studies demonstrate the effectiveness of nutritional ketosis for weight loss, better brain health, skin health, blood sugar control, and more (1).

What is Intermittent Fasting?

Intermittent fasting is a fasting method where a person alternates between periods of eating and fasting.

People on any diet, keto or not, can fast intermittently to limit their calorie intake for weight loss. Aside from weight loss, intermitten fasting lowers inflammation and improves health conditions like diabetes, heart disease, and even cancer. This is according to hundreds of studies (2).

How Does Intermittent Fasting on Keto Work?

Intermittent fasting on keto can be done in various ways. Your method of fasting depends on what you can tolerate, how long you can go without food, or your schedule.

Here are the different intermittent fasting methods:

  • Spontaneous meal skipping – This is a great option for beginners and those who don’t want to follow a structured fasting plan. Just skip a meal or two. Breakfast is the easiest. This would be a shorter fast compared with the rest.
  • 16/8 method – This method entails eating within an 8-hour window and fasting for 16 hours. You can do the 16/8 plan every day if you like. You might enter ketosis while doing this fast if your glycogen stores aren’t full and you’re engaging in lots of activities.
  • One Meal a Day (OMAD) – As the term implies, OMAD requires you to eat only one meal in a day and fast for the remaining 23 hours. If you live an active lifestyle, it’s best to save your eating time after your active hours.
  • 5:2 diet – On this approach, you’ll only need to limit your calorie intake to 500-600 for 2 days and eat normally for the remaining 5 days.
  • Eat stop eat – This is a 24-hour fast that can be done once or twice a week. If this is your first attempt at fasting, we don’t recommend jumping into this method. Start with shorter fasts and slowly work your way up.
  • The warrior diet – This diet has been based on the eating patterns of ancient warriors. To do it, you’re going to consume as much food as you like in the evening while eating very little within a 20-hour period during the day.

Any intermittent fasting strategy works for you. But the one that will make you feel your best all depends on your circumstances.

How Many Hours Should You Intermittent Fast on Keto?

When it comes to the number of hours, intermittent fasting on keto can be as short as 4 hours if you do spontaneous meal skipping – breakfast, for example. It can also be as long as 24 hours. The longer you fast, the more likely your body enters ketosis due to a depletion in your liver’s glycogen stores (3).

Why Combining Intermittent Fasting and Keto Is Popular

By now, you already know that keto and fasting both help with a person’s fitness and health goals. Using them together brings about greater results for a lot of people.

This is especially true for individuals who have a very hard time losing weight on a typical regimen. For example, exercising alone while taking your diet for granted won’t offer much help (4).

Individuals who need to improve their health numbers such as blood glucose, cholesterol levels, and blood pressure, will also benefit from this combined approach. This is done to lower their risk of disease or control/reverse their condition (5).

Who is Intermittent Fasting and Keto Combination For?

If you’ve been sticking to the keto diet for quite a while now, incorporating a keto fast will take your efforts and results to the next level.

Assuming that you’re already fat-adapted on keto (no cravings, brain fog, and low energy anymore), then fasting would be easier to do. For beginners, I would recommend trying meal skipping first.

Certain individuals with diabetes, PCOS, epilepsy, and cancer may have been advised by their doctors to follow a ketogenic diet. Including a fast in their regimen may improve their health and well-being (6)(7). Note: Because the keto and intermittent fasting combination is more restrictive, medical supervision is required.

Last but not least… Let’s say you’re interested in the keto diet and a strategy that will speed up ketosis. Intermittent fasting will increase your ketone body production. But here’s the catch: While it’s effective, you’ll probably feel so uncomfortable if you’re not used to fasting in the first place.

What Are the Benefits of Combining Intermittent Fasting with Keto?

Keto and intermittent fasting results in the following:

  • Weight loss (water weight) in the short term
  • Fat loss as you maintain this approach
  • Overcome a weight-loss stall or plateau
  • Helps you reach nutritional ketosis faster
  • Lowered blood sugar and insulin levels
  • Reduced inflammation via autophagy
  • Improved heart and cognitive health
  • Helps achieve clearer skin

Doing both diet techniques together rather than alone has a compounding effect on your body. And if you’re looking to boost your general health, there’s no reason why you shouldn’t give it a try.

How to Start an Intermittent Fasting Keto Approach

Want to know how to intermittent fast on keto? In this section, you’ll learn five helpful strategies to get started while making this experience as manageable as possible.

Don’t do them together right away

Implementing both techniques early in your journey might overwhelm your body. Start the low-carb keto diet first, then include intermittent fasting after a few weeks. This should give your body time to adjust to its new fuel source which is fat.

Decide on the best timing

The duration of your fast on keto is totally up to you. Consider how long you’re able and willing to fast. If you’re not accustomed to going longer without food, try skipping breakfast first. Then slowly increase the duration. Also, keep in mind that longer fasts, such as 24-hour hour fasting, are not necessary for optimal health.

Plan your meals ahead of time

Planning is everything! During your eating window, you’ll want to nourish your body with nutrient-dense foods. Make sure they’re low-carb, keto-friendly. Avoid processed foods. They’re more likely to trigger overeating and weight gain. If possible, prepare your meals in advance.

Keep yourself accountable

What do you think will help you stick to your intermittent fasting plan? Is it telling your friends and family about your goal? Writing it down in a journal? Doing it with an “accountability partner”? Setting milestones and rewarding yourself for reaching them? To succeed at fasting on keto, being accountable is important.

Stay hydrated

Water won’t break your fast. Plus, it’s essential to stay hydrated during a fast to prevent or relieve headaches, tiredness, and mental fog.

And in case you’re wondering, coffee and tea can also be consumed while fasting. Just keep it under 50 calories to maintain a fasted state.

Intermittent Fasting Keto Meal Plan

A lot of people ask “What should I eat during my eating period?”. Here’s what you should know: The right meals will nourish you properly and help you feel your best so you’ll go into your next fast with ease.

I’ve anticipated that you might be needing a keto intermittent fasting meal plan. So here’s one for you. Feel free to tweak/modify it according to your preferred timing or food choices – for those on a keto sub diet like Mediterranean, Carnivore, or Pescatarian!

Day 1

  • Meal 1: Scrambled eggs and bacon
  • Meal 2: Ground beef casserole

Day 2

  • Meal 1: Black coffee with butter and/or MCT oil
  • Meal 2: Grilled chicken breast with seasoning

Day 3

  • Meal 1: Breakfast sausages with scrambled eggs
  • Meal 2: Avocado and grape tomato salad

Day 4

  • Meal 1: Slices of ham and cheese
  • Meal 2: Bunless keto cheeseburger

Day 5

  • Meal 1: Boiled eggs
  • Meal 2: Cream cheese-stuffed peppers

Are There Any Health Risks of Doing Keto and Intermittent Fasting Together?

While the keto diet with intermittent fasting has many potential benefits, it is not for everyone.

If you’re trying to recover from an eating disorder like anorexia nervosa, this isn’t the right plan for you. This restrictive approach might just trigger unhealthy behaviors and put you at risk for nutrient deficiencies (8).

Pregnant or breastfeeding women should not do it. This is a crucial time in their lives to support their bodies by eating enough calories and their baby’s growth and development.

And finally – if you think that this isn’t the best weight loss or healing approach for you, then don’t do it. Being able to enjoy your journey will increase your likelihood of long-term success. So, find another plan that resonates well with you!

Final Thoughts

Intermittent fasting appears to be a natural approach for people already on a keto diet. In fact, many studies demonstrate the effectiveness of combining them for faster ketosis, weight loss, and overall health improvement.

But like with any other diet approach, a keto fast is a great fit for certain people. For example, those who are mentally and emotionally ready for it, and aren’t pregnant or breastfeeding.

Finally, talk to your doctor about this before getting started. If you’re currently taking any medication, it may require some adjustment to avoid an extreme drop in your blood sugar or blood pressure. Any diet techniques won’t be worth it if they end up causing you harm. You’ll want to do this the safest way possible.

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Evidence based

This article is based on scientific evidence, written and reviewed by experts.

The founders of Ketogenic Buddies are health care professionals. As we grow, we include other qualified subject matter experts as part of our content team.

This article contains scientific references. The numbers in the parentheses (1, 2, 3) are clickable links to peer-reviewed scientific papers.