Intermittent Fasting- How it Works and 5 Types Explained

Why is this important now?

As we enter a new month I’m reminded of the power of intermittent fasting. I’ve recently gotten over an acute seasonal illness, my immune system has recovered, and I’m reminded of how good it feels to be healthy again. With that in mind, it’s time for my quarterly prolonged fast to help bolster healthy aging and allow many of my organ systems time to recover and rejuvenate. As I brushed up on the research online and available resources, I couldn’t find many good articles that covered the different time frames of intermittent and prolonged fasts from an hourly perspective and beyond. The goal of this piece is to walk you through how intermittent fasting works, five types/progressions of intermittent fasting, a brief look at prolonged fasts, and their potential use cases. 

Who is this approach not for?

Individuals who are diabetic should always consult their physician before adopting an approach to intermittent fasting. If you have type-1 diabetes it is extremely unlikely that this approach is for you. Individuals who have past or current experience with disordered eating should also refrain from using this approach as the time-based “rules” are likely to trigger a relapse. 

How Intermittent Fasting Works

There are many approaches to intermittent fasting but today we are going to focus on sustainable strategies that are based on a daily target for fasting to eating ratios. This approach provides you with a simple way to scale up or down based on your lifestyle. We will work our way up from the smallest to the largest fasting to eating ratio. 

There are four significant stages of fasting in the human body. 

1. 0-3 Hours- Fed State, Growth Period (Anabolic)
   Your body is still digesting and putting the nutrients to work.

2. 4-24 Hours- Catabolic
   This is where your body starts tapping into stored energy for fuel, stored glucose (glycogen) for the majority of the window, and stored fats (ketones) towards the very end.

3. 24-72 Hours- The Ketone Zone
   Now you’ve depleted the majority of your stored glucose (glycogen) and you are primarily relying on ketones as your main source of fuel.

4. 72+ Hours- Prolonged Fasting State
   Here you experience further reductions in circulating insulin, glucose and can see a lowering of IGF-1 among other factors that have been shown to promote healthy aging.

Intermittent Fasting will focus primarily on the second stage, 4-24 hours or the Catabolic window.

With this understanding in mind, you can see that the goal is to tap into existing energy stores daily, making our way further into rest and repair by tapping into stored glucose and fats for fuel. We do this each night when we sleep, so one tactic that many find helpful is to use this natural fasting period as an anchor for their daily fast. We will cover a systematic way that you can use your daily sleep to level up your recovery with intermittent fasting. So without further delay, let’s dive into the 5 types of intermittent fasting from bottom to top. 

1. Before Bed Fast- 11:13
   This is a great starting point for most individuals. Even if you have no interest in fasting this approach can help you sleep better and improve daily recovery as a result. If you remember above, we are in a fed state up to three hours after eating. Our bodies are digesting the meal, processing the nutrients, and distributing the energy, building blocks, and more throughout the body. By finishing your last meal at least three hours before bed, you are going to bed post-digestion, in a catabolic state which helps you to begin the rest and repair process even faster. With the average night of sleep being eight hours in length, adding this three-hour fast before bed gets you to an 11-hour fasting window each day. For example, if you go to bed at 11 pm each night, try finishing your last meal by 8 pm.

2. Breakfast Extension- 12:12
   Step two is extending your fast in the morning before your first meal. By waiting an hour before you have your first meal you are able to capitalize on your pre-existing fasting success. You can still have black coffee, water, etc. to begin your day and hydrate. I typically have water, LMNT electrolytes, and black coffee with a touch of stevia sweetener. Many people can see significant health benefits from just these two stages in combination. Using the example from above, if you’re asleep by 11 pm, wake up at 7 am, then you can hydrate and wait until after 8 am to have your first meal.

3. The Middle Ground- 14:10
   This stage of intermittent fasting provides a nice transition into a longer fasting window. At only two hours more than the previous step, it allows you to experience a slightly deeper fasted state without altering your daily routine too much. Many individuals who don’t typically eat breakfast find this to be an easy (and often welcomed) adaptation. If we continue with the example used so far, you would have your first meal after 10 am.

4. The Fan Favorite- 16:8
   This protocol is one of the most popular approaches to intermittent fasting. It provides you with a daily 2:1 fasting to eating ratio which provides an even deeper fasted state that allows the body more time for recovery and repair processes. This is the protocol that a few of us on the team use daily as it is sustainable and fits our lifestyles. With this level, you would begin eating at noon using the example scenario.

5. Extended Fasts- OMAD, 24 Hours, and Beyond
   Now we enter the territory of extended fasting. To repeat, the above intermittent fasting types are more sustainable and can be used daily. The following extended options are not meant to be used frequently, and should only be performed with medical consent from your physician.

   
   Known as the Warrior Diet or OMAD (One Meal A Day) individuals have a 1-2 hour eating window where they consume their primary meal for the day. This approach is not sustainable physically, or socially for many as it’s challenging to get an adequate amount of calories from just one meal, and you’re potentially missing out on two important opportunities (meals) for social engagement daily.

   
   24-hour fasts tap into “The Ketone Zone” mentioned above and begin to significantly lower blood glucose levels. With proper guidance, many people incorporate one day of 24-hour fasting per month or quarter as an opportunity to dive into the benefits of a deeper fasted state a few times per year.

   
   Finally, we approach 72+ hour fasts. These are more significant mentally and physically. It’s imperative to incorporate adequate hydration and electrolytes when embracing this approach. Individuals who do use this tend to incorporate it less frequently on a quarterly or yearly basis to experience the benefits of autophagy and give the body a deeper reset.

   Whatever you choose, be sure to enjoy the meals you have with the ones you love!

In Health, 

- Shiloh