7 Fundamentals You Should Know About Intermittent Fasting

nutrition Dec 07, 2021
7 Fundamentals You Should Know About Intermittent Fasting


Are you trying to work on your mid-section? Do you want to reverse diabetes? Are you worried about your cellular adaptability and longevity?  

One of the oldest but recently in vogue trends in nutrition is intermittent fasting (IF). 

Fasting has been practiced for thousands of years. More recently, it has been adapted as a means for improving the obesity crisis. In addition to weight loss, benefits of IF include:

  • Reduced cardiovascular risk
  • Mitigation of diabetes
  • Improvement in neurodegenerative disease
  • Improvement in inflammatory conditions

Best yet, this new/old tradition costs zero dollars, requires little extra thought, no special products, and IT WORKS! Read on about the highest-yield, passive thing you can do on your path to #maximalbeing


Traditional Fasting

In many religious cultures, fasting is a means of spiritual cleansing and is an example of sacrifice. Traditional fasting may limit a specific food, eating at a specific time of day, or restrict of all food and water. IF is different than traditional fasting as it allows certain liquids in liberal quantities.


How does IF work?

Metabolically, we utilize our food for energy to fuel cellular processes. Glucose is stored in the body in the form of glycogen. Glycogen lives in muscle and liver cells and can be accessed quickly to give energy for activities (like exercising). When you take in more fuel than needed the excess energy is stored as glycogen in muscle and liver cells and as fat. When glucose and glycogen are in short supply, our bodies utilize fat in the form of ketones as energy.

Think of your body as a hybrid car. Fat is your battery, glucose, and glycogen are your gasoline. If your car is low on gasoline it uses the battery as backup.



The process of mobilizing fat stores as energy is what the ketogenic diet relies on for weight loss (A new post on the Ketogenic diet is coming soon!). Ketones are the byproduct of fat breakdown.

During fasting, the body’s glucose is depleted and fatty acids are released as a source of energy. These fatty acids travel to the liver, where ketones are produced. Ketone levels rise at around 8-12 hours of fasting and reach higher levels at 24 hours.

Regardless of your dietary approach (ketogenic or non-ketogenic), IF will cause ketosis. Therefore, IF pairs well with a ketogenic diet and the two have additive effects.  


The Biochemistry

When in ketosis, ketones enter cells to make energy using the tricarboxylic acid (TCA) cycle. They signal FGF21, CREB, brain-derived neurotrophic growth factor (BDNF), and NF-kB. These compounds improve your ability to use glucose in the cell, particularly BDNF in the brain. (Figure from https://www.nejm.org/doi/full/10.1056/NEJMra1905136).



During ketosis, the body also uses cellular machinery to shift the ratio of vital cofactors (NADH, ATP or energy, cAMP) leading to increased transcription factor signaling (messengers in the cell-like FOXO, PGC-1alpha, NRF2, and SIRT). These signals lower insulin-like growth factor 1 (IGF1), which improves insulin sensitivity and decreases the anabolic mTOR pathway which is responsible for growth in cells.

The cumulative effects of all of the above are:

  • Improved insulin sensitivity (better diabetes control)
  • Greater cell efficiency for power production
  • Improved recycling of damaged cell structures (decreased cancer cell production, slowed aging, better responses to stress)
  • Weight loss, one study demonstrated decreased body weight (6%), decreased fat (11.4%), and no change in muscle or bone mass (concerns about blocking cell growth do not appear to apply to muscle mass and on a personal note, this has not been my experience)

Figure from https://www.nejm.org/doi/full/10.1056/NEJMra1905136)



What does this look like in people? 

There are data to support fasting for obesity, diabetes, cardiovascular disease, cancer, inflammatory states, neurodegenerative diseases, and possibly autoimmune diseases.



IF leads to weight loss! Studies of IF have shown long-term maintained weight loss results that are equivalent to calorie-restricted diets. This means that you can eat a normal amount of food during non-fasting times and that you don’t need to be calorie-restrict.



IF regimens (4:3, or three 24-hour fasts) lead to improved insulin sensitivity in people with pre/diabetes.



Cardiovascular Disease

In studies, IF prevented the development of cardiovascular risk factors. These results were seen at 2-4 weeks into the regimen. In obese persons, weight was reduced, as were surrogate markers for cardiovascular disease.



IF shows promise in certain cancer populations. Using the mechanisms of mTOR suppression and autophagy (cell recycling), IF has the potential to impact tumor biology. Preliminary research demonstrated delayed tumor progression in glioblastoma patients. Studies are ongoing in many other cancers (colorectal, breast, prostate, endometrial) and this area demonstrates the potential for more benefits of IF.


Inflammatory States

Inflammatory conditions are often exacerbated by foreign proteins (ie. gluten), as well as higher caloric intake. In asthmatic patients, alternating-day IF led to improvements in asthma-related symptoms as well as weight loss.


Neurodegenerative Diseases

A 2-month IF regimen showed benefit by reducing the symptoms of MS.


Autoimmune Diseases

Potential conditions that may improve with IF include rheumatoid arthritis, lupus, stay tuned for results!

With a world of potential benefits, the next question is…how do I FAST? 


How to Fast, Intermittently

Seems simple enough right? Just don’t eat. A lot of questions can come up can I have liquids? What liquids can I have? What if I GET HUNGRY?

You may notice that you are hungry at a specific time each morning. The stomach does function on a circadian rhythm, so yes it wakes up when you do. This is why your stomach may “get thrown off” when traveling across different time zones. Yet, a lot of the hunger mechanism is psychological.

 When you first start IF, you will have a tough time and YOU WILL GET HUNGRY. With time your body and mind will adapt, and the hunger will subside. Part of this adaptation is psychological, but physiology plays a role as well. 

The levels of two hormones, leptin and ghrelin, change when you do IF. Leptin is your conscious satiety (“full”) signal. When elevated it will say “you are satiated.” The opposite is true with ghrelin. Ghrelin tells you to eat. As pictured below, you can see the variation in these hormones during certain times of the day and the decline in ghrelin during periods of fasting. 

Images are from the book The Complete Guide to Fasting Dr. Jason Fung and Jimmy Moore.



These fluctuations demonstrate that IF is difficult at first, but as you continue with IF, your physiology and psychology will adapt!  

Image from the book The Complete Guide to Fasting Dr. Jason Fung and Jimmy Moore.



The IF regimen allows users to drink:

  1. Water
  2. Water with added minerals or a slice of citrus
  3. Bone broth (stock) with or without added sea salt (video on how to make bone broth is coming soon!)
  4. Kombucha (video on how to make bone broth is coming soon!)
  5. Tea
  6. Coffee with a small amount of fat (cream, half and half, butter, ghee, coconut oil).  

What about sugar in kombucha? The sugar added to homemade kombucha is mostly consumed by your SCOBY to make acid and carbon dioxide making the final sugar content very low. I am not certain about the store-bought stuff; I suggest reading the product labels. Follow this LINK TO OUR DISCUSSION OF KOMBUCHA. 

Adding sugar to your coffee or tea is not permitted during IF as the sugar will interfere with your insulin sensitivity and ketone generation. Definitely do not add artificial products like creamers to your beverages (see this related discussion: Why Your Drink is Your Enemy). Really, you should never drink artificial sweeteners. You can add natural fats like cream, butter, ghee, or coconut oil to coffee or tea. These fats will augment the ketogenic process without impacting your insulin signaling. 


Timing is Important

Several IF regimens are described, each with pros and cons.  

You will lose weight immediately during times of fasting (up to 5 lbs). This weight reduction is water weight. Try not to get hung up on this fluctuation. Remember, the number on the scale is not important!

Why do you lose water weight so rapidly? Water is retained by glycogen (glucose stores). Once your glycogen is depleted from the liver, you retain less water, and you lose weight. Once you refuel, you gain it back…again, don’t worry about this! 


IF Regimens 

12 Hours

This is the typical practice of most Americans (stop eating at 8 pm and start at 8 am). This regimen will only lead to small benefits, for the reasons stated above (ketone generation starts at 8-12 hours).


16 Hours, 20 Hours, Alternating Day, Extended IF

We recommend 16:8, 20:4, alternate day,s or extended plans.



We believe that16:8 is the most practical if you are active. This plan allows you to fuel adequately after fasting to maintain performance in the gym.

The 20:4, alternating day and extended plans require more planning and may require adjustments in your gym routine, depending on your current activity levels. With these regimens, you will see benefits more quickly.



Choice of regimen depends on your goals. The record for the longest fast was 382 days! During this fast, Angus Barbieri went from 456 lbs to 182 lbs. I am not suggesting this as a goal, but it is an example of what a human can do when she or he puts their mind to it!


IF Myths

The number one myth I have encountered is that fasting will “eat up” your muscles. This is NOT true. Suppression of the mTOR pathway may influence the potential for growth. However, your energy backup, once glucose is gone, is fat (as described above). It takes a lot of energy for your body to break protein down to use for energy and it would be a more extreme situation than the fasting regimens described in this article for your body to reach this point. Also, if you take in adequate amino acids during your refeeding time, you will continue to gain muscle.  

Another IF myth is that you are going to go into “starvation mode.” It is very unlikely that you will be in starvation mode with a 24, 36, or even a 48-hour fast. Starvation mode occurs in extreme situations where one is starved of food, liquids, and minerals, particularly phosphorous. This will not happen with IF as you are using liquids with minerals.

The next myth is that it is healthy to eat many meals per day or to eat continuously. Based on the biochemistry described above, this is not true. When food is eaten, particularly glucose, the body will use insulin to decrease the amount of sugar in your bloodstream and will store that sugar as glycogen and fat. Over time, the ability of insulin to control glucose may blunt, which causes changes in fat storage and body composition. Additionally, in response to energy (food) surplus, the body will store the excess in muscle, the liver, and your thighs.


Doc Mok’s Experience

I started IF in January 2020 after reading The Complete Guide to Fasting Dr. Jason Fung and Jimmy Moore. I fast from 8 pm to noon. I exercise in the evening so I have adequate fuel available for exercise. I use the above-mentioned liquids as needed. For me, this is leading to a gradual loss of weight around my middle without a change in my muscle mass or ability to achieve gains in the gym. I have seen an improvement in my squat, bench, strict press, deadlift, clean, press, and jerk while using IF. I have kept my protein intake high (1-1.5 g/lb) and ensured that I take in adequate calories without any suffering in the gym.   



Intermittent fasting is effective, easy to implement, and will help you reach your wellness goals. Numerous health benefits have been shown including weight loss and improvement in diabetes, cardiovascular disease, cancer, inflammatory conditions, and neurodegenerative disease. Use adjunct liquids to maintain your fluid balance, and implement the 16:8, 20:4, or alternate-day regimens to support your journey to becoming an optimal human.


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