What is intermittent fasting? What isn’t it? How does intermittent fasting work its magic? Is it really all that magical? Who should be intermittent fasting? Who shouldn’t? We answer all these questions and more in this episode where we take a deep dive into intermittent fasting where we reveal 10 of the top benefits plus what NOT to do. Enjoy!
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Just like with Keto and other diets, there’s a lot of noise out there when it comes to intermittent fasting — even though it’s NOT a diet — with people buzzing on both sides of the fence. There’s also a ton of confusion about what is (and what isn’t) intermittent fasting as well as the benefits of intermittent fasting — with chasms between what’s evidence-based and what’s simply hype.
In this episode of BioTrust Radio, Shawn and Tim will help you clear through the intermittent fasting clutter. Here’s what you can expect to learn:
- What the heck is intermittent fasting anyway? Is it really “new”?
- What are the different types of intermittent fasting? (Hint: Time-restricted feeding is a form of intermittent fasting, but not all intermittent fasting is time-restricted feeding.)
- What are 10 of the top research-based benefits? (Spoiler alert: cognitive clarity, weight loss, appetite management, anti-aging, reduced inflammation, improved oxidative stress management, better metabolic function, increased ketone production, detoxification (cellular autophagy), and improved mitochondrial function)
- Who should practice intermittent fasting? Who shouldn’t?
- How do Shawn and Tim incorporate intermittent fasting?
- How does intermittent fasting work? When it comes to weight loss, is it really magical? In other words, does what and how much you eat really matter if you’re fasting?
- What can you eat — if anything — when you’re fasting?
- How can you use intermittent fasting to help you combat jet lag?
- What the heck is social jet lag and how can you avoid it?
- How does intermittent fasting affect circadian rhythms?
- Are most people doing time-restricted feeding WRONG?
And much, much more…Enjoy!
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And remember… you’re just one decision away from better health and a better body!
Resources from This Episode:
- The Warrior Diet by Ori Hofmekler
- Natural Hormonal Enhancement by Rob Faigin
- The Every-Other-Day Diet by Dr. Krista Varady
- The 2-Day Diet by Dr. Michelle Harvie [website]
- The Longevity Diet by Dr. Valter Longo [website]
- Satchin Panda: My Circadian Clock & The Salk Institute
- Dominic D’Agostino
- Intermittent fasting resources from Tim Ferriss
- 7 Circadian Rhythm Tips to SUPERCHARGE Your Energy and Health [BioTrust Radio #19]
- The ABCs of the Keto Diet: Avocados, Bacon, Coconut oil, and beyond! [BioTrust Radio #28]
- Health Benefits of Intermittent Fasting (Does it Work? Is It Safe?) [BioTrust Blog]
Transcript – A Deep Dive into Intermittent Fasting (DON’T do THIS)
Shawn: And we are back with another episode of BioTrust Radio. I am here, Shawn Wells, with my fellow host, Tim Skwiat.
Tim: I am here as well.
Shawn: And he’s just amazing, and I love this show. I love being on with him. I love the content we provide to you, the community, the BioTrust fam, BioTrust Nation. So, thank you for everything that you guys are doing in terms of supporting us and directing the content, and sharing the content, and all that good stuff.
This episode, you know, we’ve talked a lot about keto, we’ve talked about paleo, and we’ve talked about dieting strategies. One that we’ve gotten some questions about that people want to know about, that’s certainly hot right now, a lot of talk about it: intermittent fasting. There’s time-restricted feeding, there’s fat fast, there’s dry fast and wet fast, and bone broth fasts.
Tim: Bacon fast.
Shawn: Bacon fast, egg fast, different windows for the time-restricted feeding; 16 and 8, 20 and 4, every other day, alternate day, whatever. There’s so much that it really demands its own episode, because there’s just a lot of confusion and a lot of things that are called intermittent fasting.
Tim: Yeah, definitely.
Shawn: So, it’s worth kind of diving in here, and hopefully providing some clarity to the listeners regarding intermittent fasting. First off, so we can better understand intermittent fasting, I guess I’ll define fasting. Fasting just means the simplest definition would be not eating, and potentially, not drinking something. But most basic is not eating. It gets a little bit more complex if you’re talking about liquid calories and shakes. Right now that’s a little bit of like an anomaly that is a real thing now. But, you know, it’s not eating. For thousands and thousands of years, it was just not eating. And it was often used to gain clarity. It’s used in the Bible to get yourself prepared for a repentant state, a state of spiritual cleansing, a state of spiritual awakening and vision and clarity. With repentance, it was to cleanse yourself of certain sins.
And it’s interesting because—and this is really true across almost all religions you can look at like—there’s some degree of fasting to get into a certain spiritual state, a heightened state of awareness. And that’s interesting because we know that fasting does a few things.
Fasting detoxes is your body. Not in the way that traditional detoxing is described in in the stores and the GNCs and whatnot, but through something called autophagy, where there’s cellular detoxing, where your cells actually clean themselves out. Now there’s something that they’re talking about called my mitophagy, where your mitochondria are getting cleaned out. And we all know that mitochondrial dysfunction—remember that powerhouse of the cell that creates ATP—that mitochondrial dysfunction is basically the genesis for almost all disease; aging on down, cancer, diabetes, Parkinson’s, Alzheimer’s, you name it. Everything is related to mitochondrial dysfunction. So, this state of autophagy and mitophagy, this detoxing, is important
The other aspect that I just mentioned that’s thousands of years old, that’s part of the spiritual enlightenment and awakening, is that you get cognitive clarity. Why? Because you’re increasing blood ketone levels and your brain’s using these ketones for fuel, and you get that clarity that a lot of executives are now chasing. This diet’s hot for executives and people that are trying to get the most out of their cognitive performance. It’s not just for people trying to lose weight and whatever. Now it’s intermittent fasting is more about cognitive clarity.
So, those both align with things that are thousands of years old. Whether you’re looking at Muslim faith or Judaism, or Christianity, or almost all these religions. I think even Native American. You can look at almost anything and fasting is integral to a part of that spiritual awakening and awareness. And interestingly, intermittent fasting is a hot topic right now, and it seems to be back. Ten years ago, I wasn’t hearing much about intermittent fasting and now I am.
Tim: That’s interesting, and that was a fantastic introduction, by the way, and really set the table for an important topic, a popular topic.
Shawn: Set the foodless table.
Tim: Set the table that’s empty. No tablecloth. Thanks. But actually, I first came across the idea of a type of intermittent fasting called time-restricted feeding. I think it’s important. We’re going to get into some definitions and delineation because intermittent fasting is commonly just kind of thrown around as a time‑restricted feeding thing, but there’s other options.
Back in 2002-2003, when I was in grad school at the University of Texas, I read a book called The Warrior Diet. And I read another book—because that was quite interesting to me—called Natural Hormonal Enhancement. And in these two books, these authors were basically talking about something that was completely novel to me. You might remember around that time being into bodybuilding and sports nutrition. It was basically etched in stone that you were supposed to eat every 2‑3 hours, at least six meals a day. And these guys, Ori Hofmekler was the author of the Warrior Diet, and Rob Fagin was the author of the Natural Hormonal Enhancement.
They basically saying something completely different, basically that you should fast all day for the most part, and eat whatever food at the end of the day. There were some exceptions, but that’s basically the take-home point was to fast for this long period of time and eat at the end of the day. And being in grad school, being a graduate assistant, taking classes, working a part-time job, that actually worked really well for me from a scheduling standpoint. So, it kind of became a bit of a habit. And still no one was doing it.
So then I became a trainer and I still wasn’t ready to throw intermittent fasting out there because it wasn’t conventional wisdom just yet, but started experimenting a little bit with some of the clients who were open to it. And they were experiencing some success, so it was kind of cool to see. I’m not saying that I’m some kind of pioneer, but it has been around for a while, a long time, like you talked about, from the standpoint from religious practice. But also, I think there’s other applications that have been around for a while, too.
So anyway, I just thought that was interesting to get into the fact that there’s some additional history there from a sports nutrition or body composition standpoint, as well. But maybe it’s a good opportunity to get into some terminology, like the different types of intermittent fasting that we may have. But one other thing that I just wanted to throw out there is that intermittent fasting or fasting is voluntary, is what we’re talking about. So, we’re not talking about starvation, necessarily.
Tim: So, just to preface that when we’re talking about intermittent fasting we’re talking about voluntary fasting.
Shawn: Right, and so what’s the difference? You mentioned time‑restricted feeding.
Tim: So, time-restricted feeding is one of probably five or six different types of intermittent fasting, and it’s the most popular and one that we’ve probably talked about the most frequently on the show. And basically, where you have a “fasting window” where you’re not eating anything. Like we talked about, it’s a voluntary fast for that period of time. And then you have a “feeding window.” And this this pattern is repeated every day. And most people, I mean everyone pretty much already has a fasting window as it is. If you eat dinner or a snack and then you go to bed, and then you eat your next meal. That phase that you’re going where you’re not eating is your current fasting window.
And for most people, I mean if you look at some of Satchin Panda’s work, like some people have a feeding windows of like 16 hours, so that’s pretty long. But with intermittent fasting time-restricted feeding, some common numbers would be 16 hours fasting and 8 hours feeding, or 20 hours fasting and 4 hours feeding. But even some people just go 12 and 12. So it’s basically just extending that fast. So, for some people it would be skipping breakfast or something like that. So that would be time-restricted feeding.
Shawn: Well, interestingly, and it’s worth saying, breakfast is about breaking the fast. Often the longest period that we would go without eating includes our period of sleep. And so, what would you do in the morning, potentially? You would have something to eat and you’re then breaking the fast. That’s where that term actually comes from. It’s not coincidental.
But then there’s other things, Tim, that’s coming up a lot. How strict are you with your intermittent fasting? Some people promote a dry fast, where you don’t even have water, which there’s some potential problems there. I don’t know I feel super‑comfortable recommending that on the show. And I would say that definitely with all this stuff, you’re going without eating, and if you have blood sugar issues, blood pressure issues, and some things like that, don’t go into this thing full steam, and do this with the advice of your doctor.
Shawn: Start with smaller windows and kind of work your way up. Don’t go crazy with this. Don’t say, “I’m going to go do a five-day dry fast.”
Shawn: And some people think that actually taking medications or supplements isn’t allowed on your fast either, which is whoa. So, I don’t want to run into any of this kind of stuff, so people be smart. We’re just trying to provide some education of what these are. But I would be more inclined, if I was going to do a longer fast and I had the advice my doctor, and I was otherwise healthy, I would do a “wet fast” and I would have electrolytes. Make sure you get your sodium, your potassium, your magnesium, and your calcium. And that includes just getting enough water every day. But sometimes, yes, you can go on a multiple day fast.
One of the things that’s kind of hot right now, from talking to Dom D’Agostino and some people like that, is they do the time-restricted feeding six days a week, where they might do a 16 and 8. I like to do like an 18 and 6. I feel like that’s the best hybrid for maintaining lean body mass and getting the most benefit.
But the next one is that one day week they do a full day fast. And that’s good for that autophagy thing we were talking about, that cellular detox, where you get some true anti-aging benefits. And we have seen that in the past with caloric restriction, which is very difficult.
Shawn: That when you’re calorically restricted, you have lower rates of cancer, you have longer telomeres, which is a marker for aging, a direct marker for aging. You have improved SIRT genes. And the Sirtuin genes are related to aging. You have improved systemic inflammation, reduced oxidation, and reduced glycation, blood sugar damage. So, all these things that are kind of mechanisms for aging are all reduced. So, by fasting and by doing caloric restriction.
So, there’s benefits to just not eating as much. Going back to what you were talking about before, when you eat all day long and you graze, that’s not the healthiest thing. I tend to think of us as like a machine that has a battery. Let’s say that battery is our heart and there’s a finite ability for that battery to be effective. And the more you’re tapping into that, constantly, the less of that battery will be available. It’s not quite that simple, but I feel like if you just are eating less then that’s less your body has to do. And it’s nice to give your body, certain parts of your body, a rest at times.
Shawn: Digestive absorption, excretion, all the stuff that your body does with this process of consuming food or beverages, there’s a lot of metabolic processes that need to go on to deal with that food. So, thoughts on this?
Tim: No, because you had brought up ketosis and ketogenic diet to some extent before, it reminds me of like, historically speaking, one of the one of the major proponents of the ketogenic diet early on—I’m talking about the 1920s—was Bernarr Macfadden. He was called like the father of modern physical culture or something like that. He wasn’t a doctor or anything like that but he used to—I use the word “prescribed” loosely—but he used to prescribe fasting to people who were not feeling well. And so basically, by fasting, his thought process was that their body did not have to divert any resources to digestion or any of the metabolic processes there. It could divert all its attention to the illness. And so that’s sometimes maybe the old wives tale like you hear like “starve a fever,” to some extent I don’t know if that’s true or not. I can’t buy into that, necessarily, but there may be some applications to that there.
But I also wanted to just kind of build on some of the things that you were talking about already. So it may be some of the benefits of intermittent fasting come down to two potential things. Really, caloric restriction may be one of the main things that it’s doing. Because by limiting the amount of time or the number of feeding opportunities you have, you tend to spontaneously reduce the amount of calories that you consume.
Shawn: There’s also a one-off of that, that your appetite is actually reduced, so you end up eating less.
Tim: Right, yeah, you’re right. And so we’ve seen that, where the appetite hormones decrease, absolutely. And also, one of the things we had talked about too is the autophagy benefits. I think that it’s probably around the 16 hour mark right where that starts to kick in, just for folks who are interested in that side of things. So the longer fasts—16, 18, 24 hours—tend to be a bit more beneficial from that cellular detoxification. So, maybe having one longer fast each week could be beneficial.
But the caloric restriction, let’s look at it from a weight-loss standpoint. Basically, intermittent fasting also goes by the name “intermittent energy restriction,” so, IER as well as intermittent fasting. There’s trials that compare intermittent energy restriction or intermittent fasting versus your daily caloric restriction. So, most people are like, “I’ve got to eat 500 calories less a day, if I want to lose a pound a fat each week.” Well, the intermittent fasting trials show that you can do different types of intermittent fasting.
One of the most widely studied versions of intermittent fasting is something called “alternate day fasting” or “alternate day modified fasting,” where basically you have a “feast day” where just eat until you’re satisfied, and then the next day you “fast” because you can have up to 500 calories. And so you alternate that over the course a week. Krista Varady, I think, is the one of the researchers behind that, and she wrote a book called The Every Other Day Diet, if you’re interested in looking into that. And then there’s also intermittent fasting protocols called periodic fasting or periodic modified fasting would be more of like five days where you eat normally and then two days where you would have like the 500 calorie dinner. And in the 5:2 diet or the two‑day diet are examples of that.
Well, those types of fasting protocols have been compared to head-to-head with your typical daily caloric restriction, and have been shown to be equally effective in terms of weight loss, if not slightly more effective in terms of metabolic health. So, what that tells us is that it’s an alternative. It’s a tool. Intermittent fasting is a tool to use for weight loss. And it also tells us that probably the reason that intermittent fasting is beneficial is because it’s restricting calories, from a weight loss standpoint.
Tim: It’s not like intermittent fasting is magically helping you lose weight, per se. So that’s another thing that it’s helping with. But one of the things that I love about it is that it’s telling us that we don’t have to have that 500 calorie deficit every single day. It’s about that energy deficit over time.
Tim: So, you could have 3,000 calories one day, 500 calories the next, and it would be like the same thing as having 1,750 calories one day or two days in a row, right?
Tim: So, I think intermittent fasting is powerful from a weight-loss standpoint for that reason, because it gives us that option and flexibility.
Shawn: There’s a new trend, a new discussion that seems hot right now, beyond intermittent fasting, to do these many day fasts. These 3-day, 5-day, 7-day fasts. Which again, I’m not necessarily recommending. You need to have your physician involved. But what do you think about that discussion?
Tim: That that’s not anything I’ve tried personally. Twenty-four hours is about the longest that I go because it’s just dinner-to-dinner, basically.
Tim: And it’s something I’m comfortable with and I feel fine with that. I haven’t really seen much data on that or much research, but I have heard people that I respect talk about it, like Dr. Dom D’Agostino, and Tim Ferriss does that every once in a while.
Shawn: Right. And I will throw out that when these people that are healthy do this, they do it every once in a while. It’s like maybe once a quarter or something like that. It’s not something that they’re doing every other week or whatever. That would be way too extreme.
So we hear egg fast, you said bacon fast, fat fast. It seems like there’s a lot of fasts out there. I don’t know. There’s a lot of different fasts.
Tim: Well, just before I get into that, one other thing I was going to mention one more type of intermittent fasting called the fast mimicking diet. So, Dr. Valter Longo and his research team have come up with this fast mimicking diet. And that’s maybe for someone who wants to kind of reap those benefits of longer fasts, but is not ready to go 3-5 days. This may be a viable option.
And so, basically, with the FMD or fasting mimicking diet, what you do is they’re on cycles of like 30 days. I think it’s a five-day period out of each month where you significantly reduce your caloric intake. So talking about like 40% of what you would normally eat. So, it’s a low calorie. Not super-low, but that’s pretty low for most people. And it is low protein also. So I think calories are like 10-15% protein and then the rest carbohydrate and fat, for five days. And what he’s seen in his research is that the biomarkers are very similar to what you would get from an actual full‑fledged fast. So, that may be an option to experiment with for people that want to really get the autophagy metabolic benefits of longer fasting, without fast.
Now going into what the question that you asked, it’s kind of a pet peeve of mine, I guess, to hear some of these things. Because first of all, the question, what is fasting? You answered it perfectly. Well, there’s no debate over what a wet and dry fast is, but fasting is the voluntary abstinence from food. So, basically that’s like anything besides water, essentially, would fit in that bucket because we said a wet fast is water only and dry fast is nothing.
Tim: At least that’s how I interpreted it. So, to me, fasting, consuming anything besides water would break the fast from a metabolic standpoint. This goes back to our topic on circadian rhythms because all the organs in our body have these circadian clocks. And so, like the liver is going to be responsible for metabolizing anything that we bring into the body besides water, pretty much. And so once it senses these other things in the body—whether it’s coffee or MCTS, or butter, or whatever—that clock is going to get started.
Now, does that matter for some of the benefits? I don’t know, but I do think it’s important to point out that pretty much anything besides water essentially starts the clock. Now, if your goal is just weight loss, then it still comes down to just how much energy you’re bringing in, how many calories. So, if you’re still reducing your calorie consumption, then intermittent fasting is still going to be effective for you. However, if you have some of these larger anti-aging and autophagy types of benefits in mind, I would suggest just sticking with water during fasting periods.
Shawn: And electrolytes.
Tim: And electrolytes won’t hurt either.
Shawn: One thing that I know is popular, it’s like sometimes people use like hot salt water, because you can get cramps. Another one that is popular is bone broth. That’s getting very popular with intermittent fasting. Well, I’ll say this. So, intermittent fasting ties in very well to other diets, right?
Shawn: And there’s been kind of a trinity of sorts with paleo, keto, and intermittent fasting. And we know that, as you were saying before, that intermittent fasting is not a diet per se. It’s really the absence of eating, like we laid out. But intermittent fasting stacks well with certain diets. I feel like it stacks well with low carb, maybe from starting with Mediterranean on down to low-carb, on down to lowest carb with keto.
But the one really neat thing about why the keto community is kind of embracing it is because nutritional ketosis can only get you so deep into ketosis. And even though let’s say in this range of like 1-3 millimoles of BHB, blood BHB—I know that’s technical for you guys listening, but stick with me—that’s probably a range where you’re getting a decent amount of weight loss. You’re metabolizing fat for fuel and all that kind of stuff. But it’s in that deeper state of ketosis that you’re getting kind of the magic that happens in the mind.
And there’s a lot of people out there that the ketogenic diet for years and years and years and they’ve never actually experienced the magic. They’ve never felt the clarity. Why? Because they’re doing net carbs, they’re doing this and that, and they’re not really that adapted. They’re in, they’re out, they’re up, they’re down, cyclical, targeted ketogenic diet. They’re eating all day long, kind of grazing like you were talking about, but eating keto. And it’s effective. It’s working for them, but they’re not getting that cognitive clarity because they’re not adding in intermittent fasting.
And I believe, with fasting, that it’s more powerful than the ketogenic diet is at raising ketones. So, my example would be a low carb diet plus intermittent fasting will get you deeper into ketosis than a ketogenic diet.
Tim: Without intermittent fasting.
Shawn: Without intermittent fasting. So, obviously, the best-case scenario is the ketogenic diet with intermittent fasting. But it’s interesting, I think, to look at how powerful intermittent fasting is for maintaining some of the results that people want, achieving the results people want like cognitive clarity, like these executives that are chasing better brain function, or students that are chasing better brain function, or some athletes.
We also know that the higher ketone levels is also one prophylactic, meaning preventing damage to the brain, at least the extent of damage with traumatic brain injury, like with MMA, like contact sports, football, soccer, all these kinds of things. But we also know it’s therapeutic, meaning ketones provide energy to those neurons when you’ve had traumatic brain injury. So, it helps with the recovery. So, it’s both preventive and therapeutic, and that’s where there’s a lot of power, potentially, in ketones. And certainly we hear ketones are hot, but intermittent fasting does have some degree of synergy with the ketogenic diet.
Tim: Right. That’s awesome. That’s a really good point that you made. And maybe even from a weight management, we’ve talked before how ketones themselves may have an appetite suppressing effect, too. So, if you think, “Oh man, with intermittent fasting aren’t I going to be super hungry?” Maybe at first, just because if you’re used to eating at certain times, your body’s going to secrete hunger hormones at those times. But as you kind of get used to not eating, it’s actually not really that big of a deal and you probably feel better without eating, or have better cognitive clarity.
It’s also super important that you pointed that synergy out between keto and low carb and intermittent fasting, because like you said at the beginning, one of the mechanistic beliefs behind why intermittent fasting may be effective is because it’s flipping a metabolic switch. And we’ve talked about this before, how the ketogenic diet does the same thing. It switches you from being a sugar-burner, predominantly sugar-burner, to that fat or ketone-burning machine.
One of the most recent papers I saw, tracing the benefits back and finding out where do those benefit from intermittent fasting, suggests that it’s this flip of the metabolic switch, shifting the body into ketone metabolism, or reliance more heavily on ketones. So, that was really cool that you mention it.
That also kind of gets us thinking mechanistically a little bit, like what are where the benefits coming from with intermittent fasting. And another one of the things that’s coming to light recently is perhaps related to circadian rhythms. And so, basically our bodies—we’ll link to the circadian rhythm show and the show notes to get more background on that. But circadian rhythm basically refers to our light/dark cycle or sleep/wake cycle. And there’s clocks throughout the body, not just that one main clock in the brain. But even our organs, like liver, has a clock in it.
And so, our bodies are really designed to eat at certain times during the day, and with the prevalence of light and food these days, it’s easy for most people to eat a lot toward the tail end of the day. In fact, if you look at some of the work from Dr. Satchin Panda, that 50% or so of calories come like after 6:00 p.m., for most people. But what his research is showing is something that you and I’ve talked about before, and that other people like Dr. Rhonda Patrick is helping spread the word, is that it’s probably going to be more beneficial for us from an overall health standpoint to be consuming the majority of our calories during daylight hours.
Tim: So, most people who do time-restricted feeding intermittent fasting tend to have their feeding window at nighttime. There may be application to moving that feeding window up during the day, from an overall health standpoint. And when I talk about that, probably specifically referring to things like metabolic health, insulin sensitivity, glycemic responses, and things like that.
Shawn: Well, it makes sense. Evolutionarily, we wouldn’t be finding food in the dark. We would be finding animals, we’d be finding plants, we’d be picking berries, we’d be digging things up in the light. Maybe it’s possible that on a full moon like some things could happen, but typically, it would be during the light, so it makes sense with our circadian rhythm, the sleep/wake cycle, that food should be consumed during those hours. And we shouldn’t be late at night eating food, getting blasted with blue light from our TVs and our phones, and listening to noise and watching violent shows that are amping up our sympathetic nervous system. And doing all the stuff to stress us that are really disrupting our circadian rhythm, disrupting our natural cycle.
There’s an endocrine cascade that all their hormones kind of follow in-suit with each other, and neurotransmitters following in-suit. So your brain health, your hormonal health is kind of all attached to this rhythm.
Shawn: So we’re destroying the rhythm. It’s literally like, if you think of circadian rhythm, and rhythm like a drum, you eating at night, you’re getting blue light exposure at night is literally someone that’s throwing an extra hand in every now and then on your drum and screwing up the beat.
Tim: Yeah, the orchestra. They’re just not playing together.
Shawn: Right, so you’re screwing up what’s natural, what’s healthy. And when you do actually have proper sleep hygiene, when you do eat on a proper cycle, when you reduce your blue light exposure, then you feel better. You feel like you’re now optimizing your body for what it’s meant for, instead of fighting what it’s not meant for. And we’re the only creatures that literally fight sleep.
Shawn: I mean, this is a prime example. So, we do a lot of dumb things with eating, as well. So, I would say that intermittent fasting, if I was going to like go back and say what’s the best execution of all this stuff, I think if you’re a ketogenic dieter, intermittent fasting makes sense. If you’re a paleo dieter, I think it makes sense for intermittent fasting. If you’re low-carb, it makes sense. I would have intermittent fasting. After I’ve adapted to intermittent fasting, started at 12 and 12, work my way up to 16 and 8, or even 18 and 6, where I was going up to maybe 18 hours without eating and 6 hours with eating. And then I would have that six days a week, and then one day a week I would just not eat for 24 hours. And I would have a wet fast for that day, where I had things like salt water, bone broth, hot tea, and things like that, and I think that would be the healthiest execution. I think keto pairs really well, with paleo it pairs really well with intermittent fasting, so those all make sense together.
I think there are autophagy benefits, like we said, for people of any diet, but it just seems like it’s the best execution paired with some of the ones that I mentioned. So, that’s probably my advice on that.
Tim: I think that’s awesome, Shawn. I’m just going to add one interesting tidbit about intermittent fasting, and this kind of fortifies its position for us to eat during daylight hours is that one of the main applications of intermittent fasting before it became popularized for weight loss was for travelling across time zones. And so, basically, what researchers found was that—and this is probably particularly for longer travel east or west, whichever way you’re going—but you can adapt more easily to your new time zone if you fast until breakfast of the next day.
So, if I was traveling, I would skip meals until I got there. And if I slept, then I would eat breakfast the next morning, and that got the circadian clock started and helped with adaptation to time zones. Because, I don’t know, for listeners who’ve traveled much can understand that it can take its toll on the body when you’re traveling across time zones. In fact, I’ve heard it’s like for every hour you travel east, it takes one day for your body to recover from that time travel difference.
Shawn: But you can experience jetlag without traveling.
Tim: It’s called social jetlag.
Shawn: This is a cool term.
Tim: So, social jetlag—thanks for teeing that one up for me—social jetlag is really interesting and it actually ties into the intermittent fasting conversation because of this effect on circadian rhythm. And basically, what social jetlag refers to is that people tend to stay up on average an hour or so later on the weekends.
Shawn: I think that’s conservative.
Tim: I think it is, as well. And they tend to sleep in an hour or so later.
Shawn: That’s conservative.
Tim: That is also conservative. Which moves back their first meal of the day on the weekend, typically. And so, just that one hour, you’re basically traveling one or two time zones just by doing that. And remember what I just said, it’s takes one or two days in order for your body to recover from jumping from one time zone to the next. For every hour, that’s one day. And so when Monday comes, and you have the case of the Mondays, it could be because you have social jetlag. Now, there’s probably other factors involved, but you probably feel like a little bit of a social hangover because a little tired, a little harder to get into Monday because of that social jetlag.
Shawn: So I gave my plan of how I incorporate intermittent fasting. I do the keto diet. For intermittent fasting, I do six days with a 16 and 8, or an 18 and 6. And I like to try and do one day a week with a wet fast. What is it that you do?
Tim: Most days, for me, my intermittent fasting would be a 20-hour fast, and there’s usually at least one day, if not two days a week, where I can go 24 hours and fast from dinner to dinner. It just works well for me. That’s just something that’s become a habit over time. It’s not to say I don’t ever eat breakfast. Like on the weekends, one day I’ll have breakfast with my girls or something like that, or if my wife wants to go out and have lunch. I have a ton of flexibility built in with my intermittent fasting, but on a normal day it’s going to be usually at least 20 hours. But if like I need to eat something, I will.
Shawn: But what about beverages during that?
Tim: Now, I will have I do have coffee in the morning and I do have some tea throughout the day, but that’s it. Salt water also. I do salt water during the day as well. Now, earlier I did say that I think that coffee and tea and stuff like that counts as like breaking the fast, so to speak. But I think it’s actually a healthy thing by, having some kind of beverage like that, especially in the morning. And the reason I say that is because it does still get your clock started.
Tim: And I think it’s important to still get the clock started. In fact, in an ideal situation, I think that it’s probably better to eat breakfast and have your 6-8 hour window if you’re going to do time-restricted feeding, from say breakfast time until mid‑afternoon and then fast. It’s just socially more difficult to do intermittent fasting that way.
Shawn: Yeah, totally agree. Well, I hope this was helpful. This is a pretty deep dive into intermittent fasting. I actually haven’t heard much of this on most podcasts or shows out there. I mean, there’s a lot of shows on keto, a lot of shows on paleo, but not much on fasting, despite it being so popular. So, I think it’s good that we did a deep dive into it. You guys have been asking for it.
Let us know if there’s some things that we missed and we can always revisit it, if it’s hot for you and you’re still wanting to know more. But hopefully, we gave you our execution of it. I gave mine, Tim gave his, so you saw the practical side of it.
And I appreciate you guys listening. We’re huge fans of you. This show is here for you. Check out BioTrust.com/VIP for the VIP Facebook community, where they talk about things like keto and intermittent fasting, and how they’re executing on it. We also have the blog and you can check out this show on BioTrustRadio.com. You can download us and subscribe on iTunes, Google Play, and Stitcher.
We appreciate you guys deeply, so thank you very much for tuning in and we’ll talk to you soon.
Tim: Take care, gang.