Sharing is caring!

What Are the Benefits of Intermittent Fasting on Keto?

by | Blog, Healthy Living | 0 comments

What happens when you combine Intermittent Fasting (IF) with a Ketogenic diet? It’s like hitting the turbo button on weight loss! Intermittent fasting involves cycles of fasting and eating while the keto diet is a low-carb, high-fat diet that’s been shown to help with weight loss, among other benefits.

When you utilize both the keto diet and intermittent fasting together, you can accelerate how much weight you lose, how fast you lose it, and enjoy a number of other health benefits.

What Is Intermittent Fasting?

Intermittent fasting is a way of eating where you alternate cycles of eating and not eating. Intermittent fasting doesn’t indicate what you should eat. Instead, it’s all about when to eat.

There are different ways to approach intermittent fasting, and frequently people find that it’s a way of eating that works well for them because it’s fairly flexible in many ways. Also, we all fast for periods without realizing it. For example, when you’re sleeping, you’re fasting.

Intermittent fasting just requires that you extend that period.

During a fasting period, you aren’t supposed to eat anything, but you can have coffee, tea, water, and other beverages without calories.

The following are a few examples of ways you can do intermittent fasting:

16/8 Method

The 16/8 method has an eating window of 8 to 10 hours in a 24-hour period. Your fasting window if you follow this method, is 14 to 16 hours in 24 hours. This specific type of intermittent fasting is known as the Leangains protocol. If you choose to do the simple 16/8 method, you might avoid any food after you eat dinner and then you would skip breakfast. Some people prefer to skip breakfast anyway, for one reason or another.

One way to follow this option is to stop eating at 8 p.m. and then not eat again until noon the following day. Most folks are typically asleep for a big chunk of this window anyway! That gives you a fasting window of 16 hours.

You can have some coffee or water during your fasting window, and this may help you feel less hungry.

5/2 Diet

With the 5/2 plan, you would eat normally for five days of the week, and then during two days of the week, you would aim to eat only 500 to 600 calories a day. So, for example, you might eat normally on Monday, Wednesday, Friday, Saturday and Sunday and use Tuesday and Thursday as your fasting windows.

24-Hour Fasts

A more restrictive variation of the 5/2 intermittent fasting plan would include eating normally for five days of the week and then doing a full 24-hour fast for the other two days. You would stop eating the night before your fast begins after dinner. Then you wouldn’t eat until dinner the next day for example and that would give you a full 24-hour fasting window. You could also do breakfast-to-breakfast or lunch-to-lunch.


There are quite a few alternate-day fasting options. You can have a full, 24-hour fast every other day, or you could limit your calorie intake to a few hundred every other day and then eat normally on the days in-between. This form of intermittent fasting is seen as pretty challenging to follow, however, so it’s best suited to people with experience.

Fasting During the Day and Eating At Night

Fasting during the day and eating at night is also known as The Warrior Diet, which was created by Ori Hofmekler. With this option, you would eat just a few raw fruits and vegetables during the day, and then have a large meal at dinner. Your eating window with this option is usually around four hours—from 4 p.m. to 8 p.m. is what most people will follow.

If it doesn’t work for you, you can still reap the benefits of intermittent fasting even without following a set schedule. For example, if you can manage and it works for your schedule, skip a meal when you can, whether that’s breakfast, breakfast and lunch, or dinner.

What Are the Benefits of Fasting?

You may be wondering why someone would skip meals, but there are some serious benefits of intermittent fasting. The concept of intermittent fasting isn’t new, but it really hit the mainstream consciousness in 2012.

Dr. Michael Mosley released a TV documentary called Eat Fast, Live Longer and also a book called The Fast Diet. Other books then came out, including Kate Harrison’s The 5:2 Diet. The release of the documentary and subsequent books piqued interest in the concept of intermittent fasting. The Obesity Code was another great book covering intermittent fasting and especially the science behind it. 

An article published by Harvard University highlighted some of the benefits of IF:

  • Aids in weight loss: When we aren’t eating, then our insulin levels are dropping. Then, fat cells can, in turn, release sugar stores that can be used as energy. If you let your insulin levels drop enough, for a long enough period of time, you can theoretically burn fat.
  • Fewer Calories: Along with some of the more complex ways IF can help you lose weight, there are simple ways as well. For example, if you stick to a relatively healthy diet, such as the keto diet, during your eating windows, you’re going to be naturally eating less often as a result of more filling, healthy fats in your diet. Therefore, less time is spent eating.
  • Helps Aid in Cellular Repair: Along with insulin blood levels dropping, intermittent fasting can help increase blood levels of growth hormone. When you have higher levels of human growth hormone, it can help boost muscle gains and fat-burning abilities of your body. The body can also launch cellular repair processes during fasting windows, including the removal of waste material from your cells. When your hormone function is working at a peak level, it also helps you lose weight. For example, lower insulin levels and higher levels of human growth hormone help the body break down fat and use it for energy. When you follow a short-term fasting plan, your metabolic rate can go up anywhere from 3.6-14%, which can help you burn more calories.
  • Lowered Risk of Type 2 Diabetes: Fasting blood sugar can be reduced by anywhere from 3 to 6% when fasting, and fasting insulin can drop anywhere from 20 to 31%. This can lower the risk of type 2 diabetes.
  • Reduce Inflammation: Inflammation is linked to almost all chronic diseases. It’s possible, based on currently available research, that if you practice intermittent fasting, it can make your body more resistant to oxidative stress, and it can help reduce inflammation.
  • Cardiovascular Health: There are certain health markers linked to an increased risk of cardiovascular diseases. For example, blood pressure, inflammatory markers, and blood sugar can all be associated with an increased risk of adverse cardiovascular events. Intermittent fasting, at least in animal studies, has been shown to reduce all of these markers.
  • Improve Brain Health: When you practice intermittent fasting and it has positive effects on metabolic markers, including inflammation and blood sugar levels, it may help facilitate the growth of new nerve cells, which can boost the health of your brain.
  • Longevity: Intermittent fasting has shown impressive results in animal studies. For example, in one study, rats that fasted every other day lived 83% longer than rats who didn’t fast.

What About Intermittent Fasting on Keto?

If you look at the benefits of the keto diet and intermittent fasting, you see quite a few similarities, so why not boost the positive effects of both by doing them together?

With the keto diet, you typically reduce your carb intake to less than 20 grams a day, so your body is then forced to use fats for energy instead of glucose. When you enter the metabolic process of ketosis, your body breaks down fats, creates ketones, and uses them for energy.  

Specifically, what are the benefits of doing the keto diet and intermittent fasting at the same time?

  • Intermittent fasting has significant benefits, even if you really don’t watch what you consume during your eating periods. If you were to watch what you ate during that time, particularly in terms of carbs, it stands to reason it would help you lose more weight.
  • Intermittent fasting may help you get to the point of ketosis faster than if you just followed the keto diet. When you’re body is fasting, you’re moving from using carbs to fat as energy and the concept is the same with the keto diet. Your body’s insulin levels and glycogen stores will naturally drop when you’re fasting, and if it’s tough for you to reach ketosis on the keto diet, IF can help you quite a bit.
  • The nutrient-dense foods you eat when you’re following a keto diet are going to help you stay full for longer, and this may help you manage your fasting periods better.

Essentially the benefits of intermittent fasting on a keto diet mean that one way of eating can build on the benefits of the other. It’s a good way to get faster results and achieve your physical goals.

What’s Considered Breaking a Fast?

When you’re doing IF, you have to be conscious of your fasting windows and ensure that you’re not, even accidentally breaking your fast, particularly depending on your goals.

The following are things that you can have while fasting, and as long as your carbohydrate intake stays below 20 grams per day, you can usually stay in ketosis:

  • Water, plain or carbonated
  • Coffee and tea without added sugar, milk or cream
  • Diluted apple cider vinegar
  • You might be able to consume some healthy fats like MCT or coconut oil. You would technically be breaking your fast, but they can help you feel fuller, and they won’t break ketosis.
  • Bone broth can help restore electrolytes if you’re fasting for long periods and only having water.

Anything with calories will break your fast, including bone broth, but won’t necessarily take your body out of ketosis.

Supplements That Break a Fast

Another issue is the use of supplements while you’re in a fasting window. Supplements that will break your fast are:

  • Gummy vitamins which often have sugar and protein
  • Branched-chain amino acids (BCAAs)
  • Protein powder
  • Supplements with cane sugar or fruit juice

Some supplements don’t have many if any calories and likely wouldn’t break a fast, including pure collagen, creatine, fish oil, and prebiotics and probiotics.

How to Break a Fast

When you do break fast, you want to choose foods that are easily digested. It’s better to avoid foods with a lot of fiber or sugar because they can cause bloating after fasting.

This is another place where you’ll see the benefits of intermittent fasting on a keto diet—the keto diet is inherently easier on the digestive system in many cases.

You want to break your fast with protein-packed, nutrient-dense foods like eggs and avocadoes.

Even if you are following the keto diet, you still want to make sure that you don’t overeat when you break your fast because it can reverse the benefits of IF.

No, IF isn’t necessarily rigidly restrictive, but it’s not an excuse to have a free-for-all with what you eat if you want to maximize the benefits.

Importance of Electrolytes When Fasting

Electrolytes include minerals like magnesium, sodium, calcium, and potassium. When you’re fasting, and especially if you do it for long periods or you are also heavily exercising, your stores of electrolytes can be depleted. Electrolytes help your body function at an optimal level, and while you’re following IF and also a keto diet, you may need to supplement with electrolytes.

Following a keto diet can also impact the balance of electrolytes in the body. When you reduce your carb intake, you process electrolytes differently. For example, when you’re on the keto diet, there’s less insulin released, so the kidneys eliminate more sodium. Sodium loss can affect the levels of other electrolytes, so this highlights the importance of ensuring you replenish your electrolytes.

How to Start Intermittent Fasting

If you’re sold on the benefits of a keto diet and intermittent fasting, getting started is often the biggest hurdle to overcome. If you’re already following the keto diet, to start intermittent fasting, consider the following tips:

  • Find a plan that works for your schedule. A good starting point for beginners is often to stop eating after dinner around 8 p.m. the previous night and continue your fast through breakfast, breaking it at noon. This is often considered a somewhat gentle fast.
  • Have a meal plan in place so that you can make sure that you’re getting enough calories and nutrients. Having a meal plan will also help you stick with the keto diet. You can ensure that you’re making your calories count by getting nutrient-dense, protein-packed foods that are going to fuel your body.
  • If you find that you’re not ready to start with a full fasting plan, even one that’s fairly easy to follow, you can also build up to it as a beginner. Take small steps. For example, start by not eating anything after dinner. Then, once you get the hang of that, maybe you delay your breakfast, and finally, when you’re ready, you can skip breakfast.
  • Consider meal prepping. When you break your fast, you’re going to be hungry, and that might tempt you to eat the wrong foods or not follow the keto diet. If you meal prep, you’ll have keto meals ready so you can break your fast in a healthy way.

Summing Up—The Keto Diet and Intermittent Fasting

Based on current research, the keto diet and intermittent fasting are two of the best things you can do for your health and wellness. By combining them, you can maximize the benefits of the keto diet and intermittent fasting and meet your goals faster, including;

  • weight loss
  • reduced risk of type 2 diabetes
  • and improved metabolic markers like inflammation and blood pressure.


Gunnars, Kris. “What Is Intermittent Fasting? Explained in Human Terms.” Healthline, June 4, 2017. Accessed January 20, 2020.

Gunnars, Kris. “6 Popular Ways to Do Intermittent Fasting.” Healthline, January 1, 2020. Accessed January 20, 2020.

Holmer, Brady. “Keto and Intermittent Fasting: A Beginner’s Guide.”, December 10, 2019. Accessed January 20, 2020. 

Kabala, Jillian MS, RD. “Intermittent Fasting and Keto: Should You Combine the Two.” Healthline, November 5, 2018. Accessed January 20, 2020. 

Izumida, Yoshihiko et al. “Glycogen shortage during fasting triggers liver-brain-adipose neurocircuitry to facilitate fat utilization.” Nature communications vol. 4 (2013): 2316. doi:10.1038/ncomms3316. Accessed January 20, 2020.

Clarke, Craig. “Intermittent Fasting on a Keto Diet.”, October 5, 2019. Accessed January 20, 2020.

Gunnars, Kris. “10 Evidence-Based Health Benefits of Intermittent Fasting.” Healthline, August 16, 2016. Accessed January 20, 2020.

Goodrick, C.L. et al. “Effects of Intermittent Feeding Upon Growth and Life Span in Rates.” Gerotology, 1982. Accessed January 20, 2020.

Lee, J et. al. “Dietary restriction increases the number of newly generated neural cells, and induces BDNF expression, in the dentate gyrus of rats.” J Mol Neuroscience, October 2000. Accessed January 20, 2020.

Barnosky, Adrienne R. “Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings.” ScienceDirect, October 2014. Accessed January 20, 2020.

Johnson, JB, et. al. “Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma.” Free Radical Bio. Med., March 2007. Accessed January 20, 2020.

Ho, K Y et al. “Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man.” The Journal of clinical investigation vol. 81,4 (1988): 968-75. doi:10.1172/JCI113450. Accessed January 20, 2020.

Tello, Monique MD, MPH. “Intermittent fasting: Surprising update.” Harvard Health Publishing, June 29, 2018. Accessed January 20, 2020.

Mawer, Rudy. “The Ketogenic Diet: A Detailed Beginner’s Guide to Keto.” Healthline, July 30, 2018. Accessed January 20, 2020.

Panoff, Lauren MPH RD. “What Breaks a Fast? Foods, Drinks and Supplements.” Healthline, September 26, 2019. Accessed January 20, 2020.

Born, Steve. “Electrolyte Replenishment: What It’s So Important and How to Do It Right.” Hammer Nutrition. Accessed January 20, 2020.

Rodal, Ryan. “Keto Electrolytes: Tips and Concerns.” HVMN, November 15, 2019. Accessed January 20, 2020.

Disclosure: As an Amazon Associate I earn from qualifying purchases. This article may contain some affiliate links and I may receive commissions for purchases made through links in this post, but these are all products I highly recommend. I won't put anything on this page that I haven't verified and/or personally used. Full terms can be viewed here: Disclaimer

Medical Disclaimer: Just in case you missed it, there is NO MD after my name. This means all information you see and read here should be taken as informational, and is no substitute for actual medical advice or treatments. Please see our full medical disclaimer here for detailsDisclaimer

Sharing is caring!