What is Intermittent Fasting?

August 14, 2020

What is Intermittent Fasting?

What is Intermittent Fasting (IF)? 

Intermittent fasting is intended to spend less time in the eating phase versus the not eating phase. Fasting can be done in many different ways. That is why it can be so accommodating to anyone with different shifts, schedules, and lifestyles (Swaine 2020). 

There are several different types of intermittent fasting that can be done with, or without, a keto diet. So, let's look at the process of fasting, benefits, and what it does to our bodies first!

What exactly occurs in the body during a period of fasting?

Right after you eat- Glucose is the quickest energy source to our bodies. Right after eating the pancreas releases insulin as a response to an elevated blood sugar as well as telling our brains that we are full. The remainder of glucose will then become stored, known as glycogen, which we discussed in a previous post.   

Four hours fasted- Insulin levels have dropped, and glucagon is then released from the pancreas to provide us with more energy. This is done by utilizing the stored glycogen, which then gets turned back into glucose. As a result, we have an elevated blood sugar, which then stimulates a release of insulin.

Twelve hours fasted- This is when the body switches over to fat fueled. The stored fat becomes broken down into fatty acids. Insulin levels will remain low, and the body begins to repair and detox. This is when the keto flu symptoms begin to occur while first transitioning into ketosis.

Eighteen hours fasted- Ketone bodies are formed from the fatty acids. This transition  can take up to seven days to fully adapt in order to switch over to the primarily ketone energy source.

History of fasting- Fasting goes back to Paleolithic times. Those individuals during this fasting period had more mental clarity and better physical health. This resulted in them becoming survivors as well as an increased chance of reproduction. These individuals ate nothing but a meat-based diet, for the most part, along with fish, eggs, nuts, roots, and vegetables. As it sounds, they were actually eating a lower carbohydrate diet (Jamka et al. 2020)!

Types of Fasting- Intermittent fasting can be done either by twelve hours fasting and twelve hours eating, sixteen hours fasting and eight hours eating, or something called OMAD. One meal a day, or OMAD, is exactly what it says just one meal a day! Regardless of which method you do, the fasting period begins after your last meal the night or day before. Especially with a ketogenic diet, the sixteen and eight fasting method is known to work the best and is easier to maintain consistently. Typically, with this schedule you would most likely eat two to three meals in a day (Swaine 2020). 

What are the benefits of IF? Weight loss is a benefit to IF due to the changes among our hormones which we will discuss in future posts. Those with type 2 diabetes are beginning to utilize IF to better manage their diabetes, blood sugars, and weight reduction. An individual that is overweight, typically has an increased risk of suffering from nonalcoholic fatty liver. The process of IF allows the liver to rid the excess fat and use it as energy rather than glucose. We are prone to chronic inflammation and pain when we suffer from any type of disease whether that is heart disease or diabetes. The inflammation among the body reduces when IF is practiced routinely. When we think of what happens during the “not eating phase” our cells have the opportunity to repair and regrow; thus, inflammation is able to be reduced. Further benefits of IF include cancer prevention, improved brain health, antiaging, and gut health (Swaine 2020). 


I know this information can be rather detailed and intense, so let’s summarize what we discussed. Ideally, intermittent fasting is designed to eliminate the amount of time that we spend eating in order to allow a continued reduction in insulin levels and blood glucose. During this phase our body breaks down fat to utilize as energy. With fat as the primary fuel source with keto it is very hard to overeat even with your first meal after your fasting window. To be successful at IF, it is helpful to use coconut oil or AMN’s MCT Powder in your coffee or tea. These fats can aid in hunger pangs while eliminating a rise in blood sugar and insulin. There are also studies out there that heavy cream can be utilized in moderation during the fasting period. However, this is a controversial method to use during while fasting. You will read many articles, as well as individuals' personal opinions, pertaining to this controversial method. Personally, through my first year of keto I consistently practiced IF Monday through Friday, and used MCT or coconut oil along with one to two tablespoons of heavy cream. So again, this will be something for you to trial and see what works for you to find the right routine!  


Again, if you have any coexisting comorbidities, you are a minor, pregnant, lactating, and so forth be sure you consult with your physician before proceeding with intermittent fasting.


Jamka, M., Kulczyński, B., Juruć, A., Gramza-Michałowska, A., Stokes, C. S., & 

Walkowiak, J. 2020. “The Effect of the Paleolithic Diet vs. Healthy Diets on 

Glucose and Insulin Homeostasis: A Systematic Review and Meta-Analysis of 

Randomized Controlled Trials.” Journal of clinical medicine, 9(2), 296. 


Swaine, A. 2020. Intermittent Fasting for beginners. Emeryville, CA: Rockridge Press