Fasting has many benefits, yet little research has been done on it. Why is this? Probably because it’s not a financially-lucrative topic…afterall, how much money can be made off people who aren’t consuming anything?
There’s also the conflation of fasting with starving, but I’m guessing that the latter is not an issue for those of you reading this.
So I was surprised and delighted when I saw a review article titled, “Effects of Intermittent Fasting on Health, Aging, and Disease,” that came out at the end of last year. Read it here.
I’ve been doing fasting of one type or another for about 16 years now. I’ve looked over most of the research that exists. Yet, I learned some new things in this article. If you’re a fan of fasting, then buckle your seats while we dive in.
(Before starting, one very common question we get is about whether or not you can take herbs while fasting. I’ve previously covered this topic in another article, read it here.)
Resilience and Disease Resistance
This would require a full weekend course in itself to fully teach, however, I’ll address some of the key points.
First up notice “Metabolic Switching,” it up near the top. On this topic, the review states,
“Periodic flipping of the metabolic switch not only provides the ketones that are necessary to fuel cells during the fasting period but also elicits highly orchestrated systemic and cellular responses that carry over into the fed state to bolster mental and physical performance, as well as disease resistance.”
Your body has several methods of producing energy. The dominant one is burning the sugar glucose. The back-up or alternative system relies on burning fat through ketones.
Yes, this can also be done through a ketogenic diet, which is currently popular and trending right now. And this diet certainly has a place. But I would argue the main way in which we enter ketosis is through fasting. (This is also historically true and more likely now, with our modern food supply which enables us to eat a lot of fat divorced from protein, at least in most locations in the world.)
Some people claim you need to be on an extremely low carb diet for several days before you get into ketosis. And that may be true, depending on how we define ketosis. But it’s not an all or nothing thing. In fact, simply reducing food intake begins to enhance ketone production. The authors, Cabo and Mattson, write,
“Diets that markedly reduce caloric intake on 1 day or more each week (e.g., a reduction to 500 to 700 calories per day) result in elevated levels of ketone bodies on those days.”
What this review points out is that it is the process of switching between these energy systems (glucose and ketones) where a part of the fasting benefits happen. My friend Dr. Mike T. Nelson calls this metabolic flexibility as covered recently on my podcast. (Listen to it here) Metabolic flexibility is a great thing to have.
Now, take a look at the final column, “Long Term Adaptations.” There are some fascinating benefits listed here that most people are unaware of.
Many may be obvious. Better use of sugars and fats is pretty obvious. And how this then impacts other systemic effects like inflammation and blood pressure are only another step from there. However, here are a couple of things that may not be so obvious…
Increased heart rate variability which is a good measure of the health of your nervous system and stress response. (Hey, I also talked to Dr. Mike T. Nelson about HRV- listen here.)
A healthy gut microbiome is important for so many healthy functions. It is interesting to think about how a lack of food is always present, as it occurs in fasting, and how it can put selection pressure on all those microbes living within you. I bet we’ve barely begun to scratch the surface as to finding all the benefits of this one.
And notably, in the end, we come to “Resilience and Disease Resistance”. Not a specific disease. IN GENERAL.
Caloric Restriction vs. Fasting
“According to Weindruch and Sohal in a 1997 article in the Journal, reducing food availability over a lifetime (caloric restriction) has remarkable effects on aging and the life span in animals. The authors proposed that the health benefits of caloric restriction result from a passive reduction in the production of damaging oxygen-free radicals. At the time, it was not generally recognized that because rodents on caloric restriction typically consume their entire daily food allotment within a few hours after its provision, they have a daily fasting period of up to 20 hours, during which ketogenesis occurs.”
Caloric restriction has long been recognized as one of the main activities that can extend lifespan. This has been shown across a wide range of species, from worms to rats to humans.
But an interesting point that was previously missed is mentioned here. The benefits that were shown in previous studies, may not have occurred due to eating less food, but rather how that food was eaten, aka intermittent fasting.
Almost all of the attention focuses on WHAT people are eating. But the WHEN and HOW is also every bit as important.
How much of the benefit comes from simply having fewer calories vs. fasting? This is a good question and one that will require more research in the future. Like all things in biology, the answer is complex and almost certainly a little of both.
Beyond Free Radicals and Weight Loss
“Studies in animals and humans have shown that many of the health benefits of intermittent fasting are not simply the result of reduced free-radical production or weight loss. Instead, intermittent fasting elicits evolutionarily conserved, adaptive cellular responses that are integrated between and within organs in a manner that improves glucose regulation, increases stress resistance and suppresses inflammation. During fasting, cells activate pathways that enhance intrinsic defenses against oxidative and metabolic stress and those that remove or repair damaged molecules.”
Just check out all the different mechanisms and pathways by which fasting impacts cellular metabolism. (And even this picture is an over-simplification!)
Once again, most people focus on fasting as a weight-loss tool. And it’s absolutely great for that. But even more so, fasting is great for making your cells stronger, more resistant to stress, and healthier.
“The research reviewed here, and discussed in more detail elsewhere, shows that most if not all organ systems respond to intermittent fasting in ways that enable the organism to tolerate or overcome the challenge and then restore homeostasis. Repeated exposure to fasting periods results in lasting adaptive responses that confer resistance to subsequent challenges. Cells respond to intermittent fasting by engaging in a coordinated adaptive stress response that leads to increased expression of antioxidant defenses, DNA repair, protein quality control, mitochondrial biogenesis and autophagy, and down-regulation of inflammation.”
Fasting in Blue Zones
Are you familiar with Blue Zones? This was a phrase first used by the author Dan Buettner to describe certain geographic regions in the world that are home to significant portions of the world’s oldest people. These include:
- Sardinia, Italy
- Nicoya Peninsula, Costa Rica
- Icaria, Greece
- Loma Linda, California
- Okinawa, Japan (important for later)
The idea was that if lots of people are living longer (and not just longevity, but the more important increased health span too, aka living longer with good health in those years), then perhaps a few things could be identified that they were doing right.
Mimic those things and you too could enjoy greater and longer-lasting health. Some of the common traits include:
1. Physical activity as part of life
2. Social and family engagement
3. Plant-based diet (not meaning vegan or vegetarian in most cases, just more plants in proportion to animal foods)
4. Moderate alcohol intake, especially wine
5. Spiritual or religious engagement
6. Stress reduction methods
You’ve heard all these things and most of them would fall into the category of common sense.
Yet, the following quote jumped out at me…
“On the island of Okinawa, the traditional population typically maintains a regimen of intermittent fasting and has low rates of obesity and diabetes mellitus, as well as extreme longevity.”
Now I can’t say for sure about the other blue zones, but my guess is we would see some type of fasting involved in most if not all of them. (Some types of fasting are rituals in many religions.)
Buettner completely overlooked this point. As previously covered, when to eat is just not on the radar of most people…at least until recent years.
“First, a diet of three meals with snacks every day is so ingrained in our culture that a change in this eating pattern will rarely be contemplated by patients or doctors. The abundance of food and extensive marketing in developed nations are also major hurdles to be overcome. Second, on switching to an intermittent fasting regimen, many people will experience hunger, irritability, and a reduced ability to concentrate during periods of food restriction. However, these initial side effects usually disappear within 1 month, and patients should be advised of this fact. Third, most physicians are not trained to prescribe specific intermittent-fasting interventions.”
This quote covers why fasting is still seen as weird by the average person, including most doctors. (Understand that mainstream doctors are not really trained in nutrition at all, and even less so on fasting.)
While fasting in all its forms is still a fringe thing, it is becoming more and more mainstream. This is good because so many people could get significant benefits from starting the practice.
This review covers intermittent fasting, but extended fasts are also a useful tool. Understand that most fasting research is only looking at people for short periods of time. Longer time frames are harder to do and will thus be more expensive for any study. But as more research begins to analyze this, I predict we’ll see even more benefits from those who engage in fasting of any type on a regular and consistent basis.
I know for a fact that extended fasts take further some of the benefits that just get started in shorter fasts. Autophagy, for example, starts up but will really get turned up as more time goes on.
You can find more details about all types of fasting and how to get started inside my book, Powered By Nature.
1. Cabo, R. D., & Mattson, M. P. (2019). Effects of Intermittent Fasting on Health, Aging, and Disease. New England Journal of Medicine, 381(26), 2541–2551. https://lostempireherbs.b-cdn.net/wp-content/uploads/2020/02/EffectsOfIntermittentFasting.pdf
2. https://en.wikipedia.org/wiki/Blue_Zone (Accessed online 2/7/2020)