The Ultimate Guide to Intermittent Fasting II – Not All Fasts Are Created Equal
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When you hear the word fasting you either recognize it from its spiritual origin or when your doctor makes you starve before a blood test. Either way it doesn’t sound inherently fun. I mean, you don’t eat any food during a fast so, how could it be fun? Well, believe it or not, there really are a lot of reasons to at least toy with fasting even for the anti-aging and longevity benefits alone.
Clearly, health in this country has hit an all-time low so taking any precautions you can should be a priority. Caloric restriction, intermittent fasting and alternate day fasting are three forms of dietary interventions that can be used to improve your health and physique.
By properly implementing and utilizing fasting you can potentially:
- Lose fat
- Live longer
- Improve health
- Reshape your physique
- Improve your muscle to fat ratio
- Improve insulin sensitivity, cholesterol, blood glucose levels and more
That’s a lot to promise from simply not eating for a few hours, right? It sure is, but if you look closely at what happens in the body during fasts you will start to understand how this is possible.
It’s well established that caloric restriction (reducing calorie intake without malnutrition) extends lifespan, provides anti-tumor effects, delays the onset/severity of chronic diseases (cancer for example), and has positive effects on cognition . To this day, caloric restriction remains the most potent dietary factor in preventing aging and maximizing lifespan .
As one group of researchers put it:
“Few environmental manipulations have been reported to consistently extend the lifespan of multiple species. CR (Caloric Restriction), the reduction of macronutrient intake while maintaining sufficient micronutrient intake, is one notable exception.” 
Restricting your calories doesn’t sound too thrilling though, especially in today’s day and age. Luckily, intermittent fasting and alternate day fasting have been shown to exhibit a lot of the same benefits as CR (caloric restriction), and still allows you to eat the calories you are accustomed to.
It’s important to recognize the difference between intermittent fasting, alternate day fasting and calorie restriction; though a lot of the benefits are the same.
- Intermittent Fasting (IF) – refers to periods of no food followed by a pre-determined window of food intake. Ramadan is an example of intermittent fasting, those who follow this will abstain from food during the day and then have a large dinner at night. Common examples of this are the 16/8, 18/6, and 20/4 fasting and feeding windows.
- Caloric Restriction (CR or DR) – refers to taking your normal daily required caloric intake and reducing it by a certain percentage (15-60%). However, during calorie restriction there is still a need for sufficient micronutrient intake to avoid malnutrition.
- Alternate Day Fasting (ADF) – is a form of IF and is exactly what it sounds like; you have a feed day followed by a fast day. This type of eating allows for more leniency on your feed days in terms of the food choices. This is a more radical approach and should only be used by advanced dieters in my opinion as the hunger pangs can be tough at first.
- Modified Alternate Day Fast (mADF) – Similar to an alternate day fast, this style of dieting has a feed day and a fast day. However, on the fast day you will break the fast with one small meal, 300-700 calories. Ideally, you’d like this to be a balanced meal. Your feed day will supply the majority of your calories.
Common fasting variations you may have heard of:
- 16/8 – 16 hour fast followed by an 8 hour feeding window – often referred to as “lean gains”
- 18/6 – 18 hour fast followed by a 6 hour feeding window
- 20/4 – 20 hours of fasting or “under-eating” in some practices, 4 hour feeding window – often referred to as the “warrior diet”
- Once a week 24 hour fast
- Twice a week 24 hour fast
- Every other day feeding and then fasting
- Feed day followed by a long fast and 1 meal on the fast day
- Using fasting periods for a “detox”
The point here is that there are many ways to fast. If you find one that fits your lifestyle and it makes adherence much easier, then go for it. But please be wary of people who bash fasting while grouping them all together. All of these forms of fasting have their own results to offer, from fat loss to life extension. So what style of fasting should you use? First, define your goals.
What Can Your Fast Do For You?
Whether you are starting a new training block or diet, you need to determine what the goal of said program is. For this plan, let’s look at what we want to achieve from our fasting period. Different forms of intermittent fasting can be included in any sort of a program, from mass gain to trying to shed body fat. Dependent upon the goal, you can tweak the timing, frequency and length of your fasting periods.
Fasting for Fat Loss:
If your current goal is a reduction in body fat, there are a lot of ways you can implement fasting into your routine. In this circumstance, the fasting period is the catalyst for igniting fat loss. During your stretches of low food intake/low insulin levels, you want to burn energy, specifically fat. You are also trying to teach your body how to run smoothly and efficiently on its stored fat. By using this fuel more often and limiting the refilling these fat stores, you can work towards a steady loss of body fat until a leaner equilibrium is reached.
In order to accelerate fat loss, you need to create an environment where fatty acids are freed and utilized. This can be done by extending your overnight fast until lunch (12 or 1pm), or stretching that fast even longer. The theme here is making sure you allow some periods where insulin remains low.
Some fasted cardio or activity during the fast, followed by some additional fasting afterwards, is a perfect way to jump start fat burning that day. Fasted exercise has been shown to lead to greater mobilization and utilization of fat for fuel as opposed to fed exercise  and has been shown to burn 20% more fat . For more information on fasted exercise read my previous article – Fasted Cardio for Fat Loss.
This doesn’t need to happen every single day. All lengths of fasts can be useful here but I’d recommend starting at 11-14hr fasts (including your overnight fasting hours) at first. So if you have never tried a fast, wake up and don’t eat for 2-4 hours to ease your way into it. As you get more comfortable or begin to desire even greater fat loss, you can add hours to your fast.
However, it’s important to remember that what you are doing during your feeding window is equally as important as what you do during the fasting period. Remember, it’s all a part of a larger plan. The calories aren’t being forgotten, only shifted around.
How it helps:
– Control appetite and therefore successfully reduce calories
– Improve carbohydrate metabolism through increases in insulin sensitivity
– Allows stored fat to potentially be released and used for energy
Anti-Aging and Health:
If your interest in fasting stems from hearing of its purported longevity effects, you want more than just the reduction in fat stores. Even though shorter fasts still offer health benefits, it’s what happens deep into the fast period that those looking for longevity are after. In the later stages of fasting, 24-36+ hours, there are a host of unique hormonal changes that I’ll discuss in more detail later on.
Aging and certain diseases like cancer occur as a result of cellular damage and the body’s response to these dysfunctional cells. The long fast is a potent stressor to the cells and the body. That doesn’t sound good, why do we want that?
It’s this stressor that boosts the resiliency of our cells to oxidative stress – this is good. This can be viewed as a potent defense mechanism that the body employs to boost our chance of survival. During this time you want damaged cells to undergo repair (through a process called autophagy), increases in neuro-peptide y (NPY), and activation of certain “longevity” genes like SIRT1.
Fasting has been linked to potentially protecting against Alzheimers , Cancer , Type II diabetes , Cardiovascular disease  and more. There are also beneficial effects seen from intermittent fasting, calorie restriction and alternate day fasting in regards to improving LDL particle size/distribution , lowering LDL levels , and reducing the risk of atherosclerosis . Another recent study found that 10-12 hours of fasting in pre-diabetic patients led to LDL (bad cholesterol) being pulled from fat cells and used for energy . With the ever increasing use of statins I think these protocols deserve more research.
Even more recently, a study out of the University of Southern California found long stretches (up to 72 hours) of fasting to trigger stem cell regeneration of the immune system . In their terms, the fasting shifted stem cells from “a dormant state to a state of self-renewal.”  They also found that fasting prior to chemotherapy treatment could prevent toxicity and limit the damage done to the immune system.
Knowing this, I think you should appreciate how easy it is to reap these benefits, simply don’t eat for a few hours. If there was a pill that showed all of the promise that fasting does, it would be a best seller. Stop and think about that for a second. Dr. Oz is on tv selling supplements that are literally proven to be utterly useless, yet people are rushing out to buy them. On the other end of the spectrum, fasting has been a part of our life (intended or not) since the inception of mankind and unlike 99.9% of supplements, actually has research supporting it’s effectiveness.
Caloric Restriction is another option when you are searching for a diet aimed towards “longevity.” The problem becomes compliance and assuring you are getting proper macronutrient and micronutrient intake. This is why intermittent fasting gives you the best of both worlds. When comparing the two, CR to IF, fasting typically leads to more lean muscle mass being retained. This is why fasting is likely to be a better option for sustainability and progress.
So, for those with these specific goals, a once or twice a week 24-36 hour fast (or longer) can be used effectively.
How it helps:
– Autophagy (cellular degradaton process)
– Activiation of certain “longevity genes” (SIRT1, NPY, AMPK)
– Increases the cells ability to tolerate stress
Why would you use fasting when trying to gain muscle? Mainly because it can help keep your cells sensitive to insulin, increase growth hormone, improve nutrient repartitioning and keep body fat in check. A fast is a useful way to resensitize your body’s response to nutrients because it serves as a break from your constant surplus of calories. Usually when people think “muscle gain,” they think that they need a lot of food. While a powerful training stimulus + adequate nutrition is necessary for muscle gain, superfluous calories and excess body fat is NOT.
Yes, fasting is technically catabolic in nature, but your understanding of catabolism is skewed. You aren’t looking to gain muscle during the fast period, but you’ll be surprised to learn the benefits some stretches of catabolism will serve you. For starters, it’s a good idea to allow your body to get rid of some of the defunct tissue that you don’t need and may become problematic in the future.
Critics will say, “Well when you’re trying to get big you can’t do it in less meals.” Just because YOU can’t do it, doesn’t mean nobody else can. Some people prefer large, less frequent meals. Get over it. Nobody is forcing you to try it. The other criticism is the over-hyped “muscle loss,” I will cover this a bit later. Where does the truth lie? Somewhere in between.
Some research suggests that having periods where anabolic processes are shut off will allow for the replenishment of satellite cells. Satellite cells are vital in our muscle building efforts as skeletal muscle can’t regenerate without them . That coupled with increased resting glycogen stores, are part of why fasting can be useful when gaining muscle is the goal.
If you are looking to gain muscle but want to use fasting you just need to time it appropriately and keep the focus on having productive workouts and ingesting the proper amount of protein and calories. For this, I’d recommend keeping fasting limited to non-workout days only. I really believe that periods of low caloric intake or fasting during “bulks” can be highly effective at keeping body fat at bay.
How it helps:
– Increase in resting glycogen stores
– Replenishes satellite cells and increases mitochondrial biogensis
– Improves nutrient repartitioning
– Increases in growth hormone
In the next part of this series I will start to breakdown what is happening at a deeper level during times of fasting and low caloric intake.
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