Mark Sisson, New York Times best-selling author and former endurance athlete, covers how to train our metabolism to run more efficiently. As we develop this “metabolic flexibility” – a reliance on fats and ketones for energy – we will likely reduce hunger pangs, burn body fat and increase our energy in the process.
Mark explains how to teach the body to source energy from stored fat and liver-generated ketones and wean ourselves of our dependence on carbohydrates. He describes what it looks like to adopt a more ketogenic diet and how to incorporate intermittent fasting as a tool for training. He also speaks to how to apply the concept of “metabolic flexibility” to other aspects of our lives.
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Within the below transcript the bolded text is Hilda
We can train our bodies to build strength and flexibility on the outside and on the inside. We can train our metabolism to work optimally, helping it to get its energy from fat that our bodies might run more efficiently on the inside and stay strong inside and out. This is episode 286. Our guest is Mark Sisson. Mark is a New York Times bestselling author, a former endurance athlete and the Founder of Primal Kitchen Foods, Mark’s Daily Apple, Primal Health Coach Institute, and a number of Primal Blueprint Enterprises. Mark breaks down what it takes to develop metabolic flexibility. The idea is to teach the body to source energy from stored fat and liver-generated ketones.
He explains how most of us have turned to carbohydrates for energy rather than fat. He describes how to make the switch to wean the body off of carbohydrate dependence which can lead to a number of problematic health conditions like diabetes and obesity. He explains what it looks like to adopt a more ketogenic diet to reduce hunger and burn more body fat while increasing energy at the same time. He also speaks about how to apply the concept of metabolic flexibility to other aspects of our lives. Mark speaks to us about the benefits of intermittent fasting and how that works in tandem with metabolic flexibility.
Welcome, Mark. Thanks for having me. It’s great to be here. It is such a strange time. It was tricky to set this up to see you in person with everything that’s going on. I know gyms have been closed, and I see you as this fortress of strength, somebody who knows how to manage and take care of his body. What have you been doing to stay strong during this time?
Physically, I’ve hit the ground running literally. I’ve been spending more time outside, walking, doing sprints because the streets are empty. It’s a perfect venue. I have a friend who has a house in the Sunset Islands here. I go over to his house and I paddle a couple of times a week. That’s more paddling than I did before this thing started. I have a fat bike which has these big 4.5-inch wide tires that I normally ride on the beach, on the sand. Now that the beach has been closed, I’ve been doing long rides up the streets twice a week. I went with my good friend, Andrew. We did an hour and a half all-out hard ride. The only drawback has been because I haven’t had access to some of the equipment I use in the gym. I’ve been doing way too many pushups and I mess my elbow up a bit. I started playing tennis, so the elbow thing has been a bit of a kibosh on my tennis, but otherwise, I feel like I’m in better shape than I was before.
You’re working harder physically. What about emotionally or mentally? How are you managing these times where there’s a lot of tension, uncertainty and fear?
It’s tough times if you are someone who’s at risk for catching this COVID. It’s tough times if you lost your business because it’s been forced to be closed. It’s tough times if you’ve lost your job. You’re not certain whether you’re going to have a job when this is over. There are a lot of reasons that people are having some turmoil in their lives and it’s a difficult thing to center and get back to, “Who am I? What is it that gives me pleasure in my life?” It’s family, friends and reading. I’ve taken the time to focus on learning. I bought a keyboard, I bought a drum set and I’m spending two hours a day banging away on the drums and trying to learn a couple of songs. Part of it is dissociation. Part of it is getting out of that mindset of, “Poor me. I’m a victim. Why did this happen to me?” Part of it is saying, “How can I take this time and reframe it as an opportunity, not as a misfortune.” That’s the key.
It makes me think about how we can stay young at heart and maybe even young biologically by having that learner posture. Do you think so?
For sure. I’ve always fancied myself as a researcher, and research is learning. I spent 35 years as a writer, as an educator, as a blogger, as a podcaster. I’ve been doing mostly reading and learning on a daily basis and the beauty of the times that we live in, it’s also a bit of a drawback. The beauty is the rabbit hole which you can go, trying to find out new information by Googling something and then seeing a link to this and the link to that. I want to consider myself a lifelong learner. On the other hand, I don’t want to accumulate information for the sake of accumulating information. For me, it has to be directed, hence the discipline behind practicing music, learning a new language or writing a new book. On one hand, it’s good to say that you’re into education, learning, being open and receptive to new information and new ideas. Part of that is however the discipline that goes along with making certain that it’s corralled, focused and gets you to where you want to be.
We want to learn from you more about metabolic flexibility. This is a term I’ve heard thrown about and it was featured in your book, Keto for Life. Talk to us about what that means and how we can apply it to our lives?
Metabolic flexibility describes a condition of the human being wherein you are able to extract energy from a number of different substrates. Most people by the time they’re 3, 4, 5 years old have already been forced down this carbohydrate-focused, carbohydrate-dependent, sugar-burning lifestyle that requires that they eat complex carbohydrates or simple carbohydrates every couple of hours to get them through the day, to maintain blood sugar, to maintain energy. They never get back to their genetic roots, which are as a fat-burning beast. Most people have the ability to extract energy from the fat that’s stored on their body or from the fat that’s on their plate of food, from the glycogen that’s in their muscles, from the glucose that’s in their bloodstream, from the carbohydrate that is on their plate of food, from the ketones that their liver makes in the absence of glucose.
Even from some amino acids being combusted such as protein. There are lots of ways in which we can extract energy if we are metabolically flexible. If we built the metabolic machinery to be able to burn fat efficiently and to use ketones effectively, but because many of us not rightly or wrongly, we were brought up this way in a carbohydrate-dense environment, we never get the chance to tap into our body fat. We go through our lives not only requiring a fresh meal every 2, 3 or 4 hours throughout the day, or in the absence of which we get low blood sugar but never tapping into our body fat stores, so we tend to accumulate 1, 2, 3 pounds a year for decades.
That’s the condition that most Americans find themselves in, overweight or obese, metabolically inflexible. They can’t even burn the fat that they have on their bodies in order to maintain energy because of the way their genes have adapted to the behaviors that they’ve adopted. They wind up being out of energy all the time, in pain, and unable to handle the amount of glucose that they take in through the carbohydrates that they eat. It becomes this roller coaster that puts everyone on the road to some metabolic dysfunction. We can call it Type 2 diabetes. We can call it metabolic syndrome. There are all manner of ways in which it manifests itself, but none of them are good.
All you have to do is walk down the street and you see people who are suffering. They can’t move about properly. They’re unhappy. They are fatigued. They’re dependent on pills for sleeping and for every other bodily function.
It’s horrible. It’s become the human condition, unfortunately. That’s why we have over $3 trillion spent on medical attention every year. $3 trillion used to be a big number, now it seems to be bandied about left and right like, “Let’s throw another $3 trillion at this or that.” The good news is that we can all require this metabolic flexibility. We are born with a factory setting that wants us to burn fat efficiently, wants us to be metabolically flexible, and wants us to be metabolically efficient. With this innate system, which is hardcoded in our genes, all we have to do is change the way we eat, the types of food we eat, when we eat, how much exercise we do. If you pick the right levers, you can achieve this metabolic flexibility and get back to the point where you are burning your own stored body fat most of the time and not needing to eat.
You can get to the point where you maintain muscle mass while you are losing weight and increase strength while you’re losing weight. You get to the point where you have energy all day long, not these wild energy or mood swings. Most importantly, you get to the point where hunger, appetite and cravings no longer run your life. You no longer think, “Lunch was so great, when is dinner?” Which most people do. With metabolic flexibility comes this superpower that allows you to tap into your own stored body fat, to go not just hours at a time, but skip meals at a time without having to think about it, without getting hungry or angry, without losing energy and muscle mass, without getting sick and to have this ability to cruise through life untethered from regular mealtimes. To use that skill to tap into next level consciousness when it comes to longevity and anti-aging, which is autophagy, this ability that the body has to, in the absence of food being consumed, the body tends to want to make repairs and do some house cleaning. That’s a remarkable benefit of metabolic flexibility that some people in a lifetime never have an opportunity to tap into.
How did you reacquire this metabolic flexibility yourself? Did you experience it? Did you learn about it first or did you live it out?
All of that. I was an endurance athlete. As a runner and a triathlete, I was consuming 1,000, 1,500 grams of carbs a day. I wasn’t gaining weight because I was burning it all off as a runner. Also, partly because I was metabolically inefficient so that not only did I not gain weight or put on body fat, my body would find ways to increase my temperature to try and burn off the excess fuel rather than stored as fat. This is a condition that some people find themselves in. If they overeat, they don’t get fat, they increase their metabolism. Some people would say, “That’s a good thing. Isn’t that good? Don’t you want a high, fast metabolism?” The answer is no, you don’t, you want to be efficient. The ideal human condition would be to get by on as few calories as possible throughout your life. That includes not being hungry. There’s a point at which when you’re eating food that you say, “That’s enough, I’m done. I’m ready to push the plate away.” Many of us tend not to have that skill and it catches up with us. Through the years, first, I cut back the amount of carbs I was consuming. I increased the amount of healthy fats I was eating. I took a look at protein and how much protein I was taking in.
Over the years when I was doing research initially for my book, The Primal Blueprint, which was focused on eating real natural food. Ironically or not, when you get rid of added sugars and industrial seed oils, the unhealthy fats, grains, getting rid of all of those things, you come down to a shortlist of food. You’ve got beef, pork, lamb, chicken, turkey, some fish, maybe seventeen vegetables. It’s difficult to get a high carb intake when you’re doing that. That’s the first level of access to get to metabolic flexibility. It’s getting rid of the crap, the sugars, and the industrial seed oils.
Our body is not going to like that. Immediately, it won’t like it. When I tried to lower my carbs drastically at one point in my life, my heart started skipping a beat. I remember going to the cardiologist, he was like, “No, it has nothing to do with diet.” I thought, “I think it does.”
Sometimes if you do that amount of bold restriction and you go from 300 or 400 grams of carbs a day down to 40 or 50, you have an electrolyte imbalance, which will manifest itself in heart arrhythmias in some people. I’ve had that happen to me. You can go overboard on this. What I create with The Primal Blueprint and ultimately with Keto for Life, The Keto Reset Diet and my other books is a template. It’s something to try out. You experiment within that template and see what works for you and what doesn’t. As you get rid of the crap in your diet, the sugars, the sweetened beverages, the pies, cakes, candies, cookies, breads and crackers, and a number of other things, and as you get rid of the industrial seed oils, the corn oil, soybean oil, canola oil, and you clean up your diet, you start to notice that you’re not as hungry because you’re eating real food that has real nutrition. It’s got micronutrients that satisfy beyond the palette and the satiety of the meal. You then get to another level where you say, “I feel like I could build some metabolic flexibility. I could train my body to become good at burning fat if I were to cut the glucose and carbs down a little bit more.” That’s what The Keto Reset Diet was about, which was not being ketogenic for the rest of your life. I’m not planning on doing that. I love all kinds of food. I use a ketogenic diet 2, 3, 6 weeks at a time the same way I would train for a 10K to build metabolic flexibility and efficiency.
Once I’ve done those several weeks of that training, I can back off and I can go back to eating some of the foods that I had otherwise omitted, but I’m using them much more efficiently. If I go through a day and I want to do a hard workout at the track, or I want to play a game of pickup basketball, or I want to run around the park with my grandchildren, I can add 50 or 100 grams of carbs with some sweet potato or something like that, and my body says, “I love this. I’m going to burn it and use it for fuel, or I’m going to store it as glycogen.” When I choose not to eat, my body says, “This is great. I’m going to burn stored body fat. I have plenty of it on me.” People hear me say like, “I have plenty of body fat on me.” I’m a 168-pound guy and I’ve got probably 10% body fat. That’s 17 pounds of fat on my body. At 3,000 calories per pound, it’s 50,000 calories worth of fat. At 100 calories per mile, I could walk 500 miles on that. We’re designed to convert extra calories that we eat in our food into energy that we carry around with us on our body. The design through evolution is so elegant, and as long as we’re able to tap into it and burn it for fuel the way we’re designed, it works both ways. You can store it, you can burn it. That’s the metabolic flexibility part. In the absence of carbohydrate for any lengthy period of time, the body says, “There’s not going to be much glucose to run the brain.” That’s fine. I’ve got a liver that’s good at making ketones. That liver can crank out 750 calories a day worth of energy from ketones if need be. Most people don’t even need half of that, even when they completely restricted their diet to zero food for five days. The liver is capable of making ketones, which the brain loves, the brain prefers it over glucose.
You have this elegant system where if you’ve become metabolically flexible, metabolically efficient. If you decide you don’t want to eat for 3 or 4 days, a lot of people now do this because they have this new skill. They can fast, water only or water and electrolytes for a couple of days. The body gets all the energy it needs from the fat that’s stored in the subcutaneous storage and some visceral fat for some people. It gets all the energy for any muscular activity. It gets enough energy to run the brain conveniently from the ketones. How do we make ketones? We take more stored fat, we convert it in the liver into ketones, and then there’s this amazing epigenetic regulation that happens in the absence of glucose, and in the presence of ketones, beta-hydroxybutyrate, which directs the body to spare protein and amino acids, and not use them indiscriminately for fuel, but to save them for structural repair and for making enzymes. You become this closed-loop system. It’s amazing how few calories you realize you need to thrive when you get to this point.
I remember talking with my father about intermittent fasting and he was telling me about the studies that show that mice that eat less live longer. I thought, “Who wants to live longer because eating is so enjoyable?” It doesn’t sound like you’re describing a diet of deprivation either.
Do not get me wrong, I love to eat. That’s one of the reasons that I’m not keto all the time because I like a variety of foods. I make sure that every bite of food I put in my mouth is enjoyable and fantastic. I don’t eat anything that doesn’t taste great. I don’t eat anything because somebody said, “You should try this dry kale salad because it’s good for you.” That does not appeal to me. I’m as hedonistic when it comes to eating as anybody. I’m not a glutton. I’ve gotten to the point where I understand not only how the body works and how little fuel I need to get by, but I also understand the nature of the wiring of the brain that would suggest that you put a giant piece of cheesecake in front of somebody. That first bite is a 10 out of 10. That’s amazing. That second bite, that’s close, that’s a 9.5. By the time you get to the 3rd or 4th bites, it’s still good, but it’s an 8, 7.5. At some point you go, “I could keep eating and finish this cheesecake, but why? I’m not getting the same enjoyment out of it.” If I know that by eating the 10th and 12th bite, I know intuitively that my heart is going to start racing, my temperature is going to increase, I won’t sleep that night well, my insulin will go up.
There will be a lot of things that happen that I could easily avoid by saying, “I’m going to stop at 4 bites or 5 bites.” The theme of my company is live awesome. I want everybody’s experience to be as awesome as it can be. I want you to extract the greatest amount of pleasure, enjoyment, contentment, fulfillment from every possible moment in your life that you can. That includes food. If you can find a way to understand how the body works and how your brain is wired with food and overcome that basal, crunchy, salty, fatty, sweet need that we all have, and understand that food is fuel, but it’s also a pleasurable, hedonistic experience. At some point, it’s too much. You can’t have too much of any good thing. I like getting a massage, but a six-hour massage, I’m not sure I’m there. You can get too much of a good thing, and food is where people go when they’re stuck in their emotions.
What do you think of this? I sometimes tell people, “Instead of trying to avoid certain things, if you fill up on the good stuff, then that will have less allure because you’ll be changing your palette.” Is that true? Has that been your experience? If you fill up on the good stuff.I mean the nutrient-dense foods that you were describing.
Part of what happens with people who are continuously hungry is if they’re eating crunchy, salty, fatty sweet, processed foods that do not have a lot of deep nutrition. The brain says, “I felt you crunching and swallowing. I sent all the hormones to where they needed to be, and I’m not getting my hit, my fulfillment here, my micronutrients that I need to operate optimally.” The body is wise in this. That’s why some people tend to not only overeat, but overeat the bad food, partly because they’re choosing bad food or low nutritious food, and the body says, “We’ve got to eat more because if that’s all we’re getting and we’re not getting enough of these vitamins, minerals, phytonutrients and other things, we need to keep chowing down on more and more food.” The opposite is that if you eat nutrient-dense foods, the body gets satisfied quickly and says, “That’s great. I’m done. I don’t need anymore.” The first thing that happens is most people say, “I was eating way too much food. I don’t need to eat that much food. It makes me uncomfortable to eat that much food. Three meals a day is a lot of food.”
Most people who have gone through this process, the first thing they’ll do is find one meal to not eat every day. For most people, it’s breakfast. You get up and you have a cup of tea, a cup of coffee or nothing. You go back to your day and then eat your first meal at 12: 30 or 1:00, then maybe have dinner. That’s part one of what happens. Part two of what happens is that first meal doesn’t even become a full meal. That first meal is like, “Take the edge off, but I don’t even need to feel full from the lunch that I’m eating.” I’ve gotten to the point where several days a week, I’m like, “I don’t even feel like eating lunch. I’m not that hungry. I’m not ravenous for anything. Nothing is appealing to me. I want to enjoy my dinner. I’ll have one meal a day.” It’s an awesome dinner. It’s not a huge dinner. It’s the same size as it would have been if I’d had another meal in the day. It’s just that I’ve skipped the first two meals. We weigh too much food not just as a society but typically as a species. You start to go into how much do we throw away, how much is wasted, and how much could be better suited for other people. With that, you start to understand we could feed the world healthy food if we wanted to because there’s enough to go around.
Mark, it sounds like you have this metabolic flexibility thing down. Please tell me a story when you didn’t have it down. Let us know that you’re human and there have been days when you’re like not pushing the plate away or not skipping a meal.
It’s most of my life. In college, I was a distance runner and I weighed 138 pounds, 140 pounds. There used to be a TV show a long time ago called Green Acres. One of the characters was this 1,100-pound pig called Arnold Ziffel. The connection there is that all my college buddies called me Arnold Ziffel because I could eat more than any of those guys in the football team. I could slam down thousands and thousands of calories of food a day. I could eat a few steaks for dinner and then have 6 or 8 desserts. It was obscene because I could, I got away with it, and I hadn’t yet understood the impact. The fact that I could get away with it didn’t mean it was good for me and didn’t mean that I should get away with it. It’s human nature for all of us to see, “What can I get away with? What’s the biggest meal I can eat and not get fat? What’s the biggest piece of cheesecake I can have and not feel like a glutton?” We tend to do that. For a lot of my life as an athlete, I had a half-gallon of ice cream every night for ten years. That was at the end of the day where I’d had at least six beers and I spread them out. I never got drunk. I would take two with lunch, one after my 15-mile run in the evening and one with dinner.
I would have a loaf of bread every day. I would have a 2-pound chicken, a 2-pound bag of frozen peas. I ate a lot. Most nights I did not sleep well. I would hear my heart beating through my eardrums on the pillow. It wasn’t until years later I realized it’s from how much food I was eating. It wasn’t from the training I was doing. I was overwhelming my body, and my body was trying to jack up my body temperature to deal with the excess calories. I was not metabolically flexible in those days. I will add to something that’s maybe a little TMI. I had IBS most of my life from the age of 14 to 47. It was horrible. I would suggest that a lot of what was going on with me was also leaky gut syndrome. I probably passed a lot of food through me undigested because of this, so the calorie that I consumed didn’t get processed as a calorie.
Thank you for telling us that information. Even though on the outside, you’ve might have looked super buff or well, but something wasn’t right on the inside. We’re getting near the end of our conversation, but I wanted to ask you a couple more things. How do you see us applying this metabolic flexibility to something other than diet in our lives? Is that a thing?
Metabolic flexibility is specific to diet, but the concept of flexibility, the concept of being pliant, mobile, non-rigid, able to pivot with the times and things that are happening in our lives that may or may not be perfect, that’s an important aspect of longevity. When they look at centenarians, these are people who have lived to be 100 years old. They look for commonalities. I know the blue zone is trying to find that there were some commonality that had to do with the minimal amount of meat consumption. Then you find populations where the people are 90, 100 years old and they smoke a full cigar every night. They drink a half a bottle of Jack Daniel’s, but the one common theme among all of these people is what we call roll with the punches. They took massive life hits, survived, rolled with the punches, pivoted and moved on whether it was a loss of a spouse, loss of a child, a massive job change or whatever it was.
In many cases, it was multiple times of this attribute, this ability to understand that life is 90% how you deal with it. It’s only 10% of what happens to you and 90% of how you deal with circumstances. People tend to want somebody to pat them on the shoulder and tell them, “That’s too bad. You’re the victim here. You were wronged and it’s not your fault.” That’s a horrible way of going about life. The way to do this is to take full responsibility for everything that happens in your life and not blame. Blame is different, but a responsibility. You get rear-ended at a stop sign where you were stopped there. It’s not your fault, but you’ve got to take responsibility for how you move on from there, whether that involves rehabbing because you got injured or forgiveness for the person behind you who may have been having a bad day. There are a lot of aspects of life that require flexibility. When we become rigid, that’s when we break when we get under a stressful situation.
What helps you forgive and roll with the punches?
It’s tough. You have to think about it. For me, it’s a conscious thing. I have to go deep when I find myself in that space and walk it back and go, “This didn’t happen to me. This happened for me. What is the lesson here? How do I move on from this?” I’ll give you a tiny example. I was in the restaurant business for about two and a half years, and I lost a ton of money and it was horrible. I’m like, “This is a terrible experience. I never want to do it again. I’m not a restaurant person.” I beat myself up for having done it. What if we had 6 or 8 successful locations? Look at what’s going on with the restaurants. If I did 6 or 8 locations, I’d be in deeper stuff now. It’s incumbent upon people to reframe whatever is going on with you as an opportunity, as a lesson. I thought I was going to do a TV show. One time, I spent a lot of money doing my own TV show because I thought this is what I was born to do. I talk about health, fitness, diet, exercise and medicine. I’ll be my own advertiser. I’ll buy time on Travel Channel. People who saw the show loved it. I lost $1.5 million quickly doing it. That was $1.5 million I didn’t have that could have been feeding my family and housing my family.
Yet, in retrospect, it’s one of the best things that ever happened to me because it was the beginning of Mark’s Daily Apple as an alternative to this. I was rigid for a number of years. I’m selling vitamins and supplements and that’s all I’m going to sell. One day I said, “I should do food. I should do sauces and dressings.” That’s what I’m writing about. My passion is food. That’s how Primal Kitchen started. Once I got out of, “I’ll make this whole supplement thing work if it kills me.” It almost did, but then greater good came out of it. Only because at some point, I said, “I’ve got to rethink this. I’ve got to reframe this. What’s the wisdom I’m trying to impart to people? It isn’t about taking supplements, but it’s about food, how to eat food and how to make food healthy and better for you. Why don’t we do that?” We did.
Now, you’re educating many people about metabolic flexibility, Keto for Life, how to live our most awesome life. I appreciate that. As we wrap up, I want to ask you the question I often pose at the end. If the reader could do one thing to improve their health, what would you recommend that they do, Mark?
Walk as much as you can. Walking is the single best exercise anybody can do.
Thanks again for your time. It’s my pleasure. It’s great being here.
About Mark Sisson
- Primal Kitchen Foods
- Mark’s Daily Apple
- Primal Health Coach Institute
- Primal Blueprint Enterprises
- Keto for Life
- The Primal Blueprint
- The Keto Reset Diet
- @MarkSissonPrimal – Instagram