I want to do something maybe a little different than the typical interview where we talk about nutrition and lifestyle and all that great stuff, which is really important, but I want to start by just learning a little bit more about your background and how you got to be where you are now. You’re really well known in the functional medicine community, nine-time New York Times bestselling author, heading up the Cleveland Clinic’s functional medicine initiative, but I’m curious to know a little bit more about how you even got interested in all this stuff. You were trained originally in conventional medicine. How did you get from there, in medical school, to where you are today?

In this episode, we cover:

4:44 How Mark got to where he is today

7:50 Where has conventional medicine failed?

15:04 Research that supports functional medicine

24:36 Future developments in the delivery of care

28:28 Mark’s new book, Eat Fat, Get Thin

Chris Kresser: Hey, everyone, it’s Chris Kresser. Welcome to another episode of Revolution Health Radio. Today I’m really excited to welcome Dr. Mark Hyman as a guest.

Dr. Hyman is a practicing family physician, a nine-time #1 New York Times bestselling author, and an internationally recognized leader, speaker, educator, and advocate in the field of functional medicine. He’s the Director the Cleveland Clinic Center for Functional Medicine. He is also the founder and medical director of The UltraWellness Center, chairman of the board of the Institute for Functional Medicine, a medical editor of The Huffington Post, and was a regular medical contributor on many television shows including CBS This Morning, Today Show, CNN, The View, Katie, and The Dr. Oz Show.

I met Mark, I think it was maybe a year and a half ago, at an event that we were both at in Arizona, and we immediately hit it off and became fast friends. He’s an extremely intelligent person and one of the sweetest guys you’ll ever meet. I have tremendous respect for his contribution in this field. He’s a real inspiration for me and many other functional medicine practitioners. He has done probably more than anyone that I can think of to move the field of functional medicine forward and help it to gain the recognition that it deserves and so badly needs in order to become a greater part of the delivery of medical care not only in the US, but around the world. Every time that I’ve had a chance to cross paths with Mark at other conferences or events that we were at, we’ve just had a great time together. I’ve been wanting to get him on the show for a number of months, but because of our schedules, we weren’t able to make it work until today, so without further ado, I’d love to introduce you to Mark Hyman. We’re going to talk all about functional medicine and the future of medicine. I hope you enjoy this interview as much as I did.

Mark, I’m so excited to have you on the show. I’ve wanted to do this for a long time, and I’m glad we could finally make it work.

Mark Hyman, MD: I’m so glad to be here, Chris.

Chris Kresser: I want to do something maybe a little different than the typical interview where we talk about nutrition and lifestyle and all that great stuff, which is really important, but I want to start by just learning a little bit more about your background and how you got to be where you are now. You’re really well known in the functional medicine community, nine-time New York Times bestselling author, heading up the Cleveland Clinic’s functional medicine initiative, but I’m curious to know a little bit more about how you even got interested in all this stuff. You were trained originally in conventional medicine. How did you get from there, in medical school, to where you are today?

How Mark Got to Where He Is Today

Mark Hyman, MD: Well, I got there the way that no one really should get there, which is similar to your story, which is getting very sick and having to figure out how to get myself better when the conventional medical approach that I was an expert in had no answers.

Chris Kresser: Right.

Mark Hyman, MD: It was through that exploration of the body from the inside out that I actually began to realize that everything I learned about how the body is organized, how we get sick, how we get better, how we define disease, is all completely wrong! There are elements of what I learned that are the foundational science, but how the pieces got put together is just totally wrong and had actually nothing to do with how human biology is organized. Through that exploration of my own illness, I began to sort of see what was out there, and I discovered Jeffrey Bland, I discovered Sidney Baker, Leo Galland, guys like Russell Jaffe—pioneers in this field who really began to rethink our approach to disease and put together a story that, it turns out, is actually probably the biggest medical discovery since sanitation and antibiotics and vaccines. I think we just really have leapfrogged forward in medicine dramatically in the last few decades with the discovery of systems thinking in biology, and functional medicine is really the clinical application of all that.

Chris Kresser: When you were getting started in all this, you mentioned discovering Jeffrey Bland. Was “functional medicine” even a term that was in use at that point, or was that still kind of evolving?

Mark Hyman, MD: Yeah, the Institute for Functional Medicine started 25 years ago, whatever that was… 1990 maybe or ‘91.

Chris Kresser: Yeah, ‘90.

Mark Hyman, MD: They started putting on conferences. The first one I went to was in ‘97. Then I went to their first certification program, the AFMCP, and I began to sort of realize that I thought this was all a well-established field, but little did I know it was just getting figured out, and I was sort of figuring it out with everybody else. With the faculty that we built, we were able to really kind of come together and put together the basic foundational principles that have now because the Institute for Functional Medicine and the certification program and laid down the paradigm of a new way of thinking about how we get sick and better that is based on causes and not symptoms. It’s based on treating the whole organism, not just organs. It’s based on not geography or where is the problem in your body, but on the mechanisms underneath the symptoms. That’s what’s really been exciting, and I got to try it on myself, I got to try it on literally tens of thousands of patients, first at Canyon Ranch as the medical director and then my own practice at The UltraWellness Center and now at Cleveland Clinic, where we launched the first academic medical center to have functional medicine in it, and it’s just exploding there.

Where Has Conventional Medicine Failed?

Chris Kresser: Yeah, I definitely want to come back to that and spend some time talking about it. This is probably a good segue into talking a little bit more about what some of the biggest problems are in conventional medicine today. You speak publicly about this, your role at IFM and the Cleveland Clinic. You’re well acquainted with all of these challenges, but let’s break it down a little bit. Where has conventional medicine really failed?

Mark Hyman, MD: I think we failed in that we’ve focused on a system of classification of diseases based on symptoms and geography—where is it in your body and what’s the symptom? If you have joint pain, you go to the joint doctor; head pain, you go to the head doctor; stomach pain, you go to the stomach doctor; you have diabetes, you go to the diabetes doctor. But as we’re learning about how the body works, this way of organizing and thinking doesn’t really work, and all it allows us to do is to group people according to symptoms, not causes, and then treat the symptoms with drugs that are usually suppressive and have a lot of side effects, so they block, inhibit, or interfere with some mechanism instead of learning how to create health. Functional medicine is really the science of creating health as opposed to the science of treating diseases.

Conventional medicine fails in that the model we have is great for acute illness. If we have a serious injury or an acute end-stage problem, it’s great. I mean, I’m at Cleveland Clinic, and absolutely I would go there if I had some serious acute problem.

Chris Kresser: Right.

Mark Hyman, MD: They’re great at it, but what they’re not great at is dealing with the burden of chronic disease, which now affects 1 in 2 Americans. It’s 83 or 84 percent of our healthcare costs, or $3.8 trillion, and we are now recognizing that we don’t have a good model to deal with this burden of chronic illness, everything from autoimmune diseases, which affect 80 million, diabetes, heart disease, cancers, digestive disorders, inflammatory disorders, skin disorders, mood disorders, cognitive disorders, anxiety, depression—these things just are not well dealt with by our conventional approach.

Chris Kresser: Do you find that there is a strong awareness of that, even within the deeper, more-entrenched establishment within conventional medicine? Are you seeing a change in the openness and awareness of this problem? What’s your experience with that?

Mark Hyman, MD: I think what’s happening is that science is catching up with everybody and that the paradigm is beginning to crack. As I got to Cleveland Clinic, I was sort of shocked to find some doctors saying to me, “What took you so long to get here?!”

Chris Kresser: Yeah!

Mark Hyman, MD: One of them was Dr. Charis Eng, Head of Personalized Genomics, and she’s one of the leading genomic researchers in the world. She told me she’s studying the microbiome in cancer and how to regulate breast cancer. I mean, this is a radical idea. No oncologist is thinking about your gut flora, but she is!

Then Stan Hazen at Cleveland Clinic is looking at the role of our diet in regulating bacteria and how that affects your risk of heart disease and that by altering your diet you can change your gut flora and reduce your risk of heart disease. Again, nobody who’s a cardiologist is thinking about your gut flora, but now these ideas are becoming almost mainstream. Things like leaky gut, which was heresy years ago now is all of a sudden written about in the medical literature as, “Oh, yeah, of course, we always knew that.” We’re seeing these concepts of inflammation, for example, across all the specialties, not just in autoimmune stuff and allergy and asthma, but in diabetes and heart disease, cancer—

Chris Kresser: Depression.

Mark Hyman, MD: Depression and dementia. Who would have thought that depression is an inflammatory disease of the brain? We thought it was a psychological issue.

Chris Kresser: Yeah.

Mark Hyman, MD: We had ideas, for example, about autism, that it was from bad parenting, right?

Chris Kresser: Right.

Mark Hyman, MD: And now we know it’s not. It’s a metabolic problem in the brain, metabolic encephalopathy. We know that depression may not be all the reasons we think people are depressed, maybe emotional issues and maybe something very physical. Obviously it can be emotional, but there are just different ways of thinking that are now emerging so that anybody who is paying attention who is a doctor or scientist can’t avoid these ideas. They’re shaking up the very paradigm of what’s going on.

It’s like all of a sudden Einstein came up with the theory of relativity, then all of a sudden the world as we know it changed. Even though people still don’t really get his ideas even today, they really altered our view of reality, that time and space are not what we thought, that time is not linear, that space is curved. I mean, how could time not be linear, but it isn’t! That solid objects are mostly empty space, that atoms are energy and not just matter. These are crazy ideas, right? The same thing is happening today in biology, and yet we’re still, from a structural and a practice point of view, mired in this old system. I think it’s starting to crack in a big way, and I’m excited about what’s happening.

Chris Kresser: Yeah, I’m really glad to hear you bring that up when you were referring to research that’s being done in the “conventional” world that supports functional medicine methodology. One of the biggest criticisms that we hear from some people in the conventional world is that there isn’t any research to support functional medicine, and I’d be curious to hear how you’re addressing that challenge both in terms of just redefining or reframing that question or what kinds of research do support functional medicine and then any specific initiatives that you are working on at the Cleveland Clinic to develop more research that could support functional medicine.

Mark Hyman, MD: There are many, many scientists working in their silos on different aspects of what’s happening, guys like Dr. Alessio Fasano who has been a pioneer in understanding gluten and the fact that there is a whole spectrum of gluten sensitivity, not just celiac, that it does cause leaky gut and it is related to a whole host of disorders that aren’t typically what we think of as gluten related. This guy is at Harvard!

You have guys like David Ludwig, also at Harvard, who is shaking up ideas about calories, that all calories are not the same, that fat and carb calories act completely different in the body. In his new book, Always Hungry?, he talks about the fact that when you increase your fat in your diet, you shut off hunger, you boost your metabolism, you increase fat burning and reduce fat storage, whereas if you eat refined sugars or carbs you do the opposite. These are really crazy ideas, that all calories are not the same. This is a heretical idea that contradicts our conventional world view, but these are coming out of the highest levels of academic research. Then there are guys at Cleveland Clinic doing studies on the gut microbiome and heart disease. These are kind of… out there.

Research That Supports Functional Medicine

Chris Kresser: Yeah, and the important thing to realize here is those are not studies about “functional medicine,” per se.

Mark Hyman, MD: No.

Chris Kresser: But there are studies about discovering what the underlying roots of illness are and how to address it at that level, which, of course, is consistent with the functional medicine approach.

Mark Hyman, MD: Right.

Chris Kresser: I think that’s a really key point for people to understand. There’s tons of research that supports functional medicine. It’s just not called “functional medicine research.”

Mark Hyman, MD: Right. Now what’s changing is that for the first time, really, in the history of the world, we’re actually doing targeted functional medicine research. Cleveland Clinic is funding literally millions of dollars of research. We’ve raised $8.5 million so far this year.

Chris Kresser: That’s great.

Mark Hyman, MD: And there’s funding that’s coming from the Cleveland Clinic directly to fund this research. We’re doing studies on reversing diabetes, getting people off insulin, on migraines, on asthma, on inflammatory bowel disease, and on autoimmune diseases. We just got a $5 million grant to study autoimmune disease, and we’re going to be looking with some of the most sophisticated researchers in the field at psoriatic arthritis and other autoimmune diseases. It’s super exciting.

We’re looking at dementia and working with the brain people. There’s a whole program there called the Lou Ruvo Center, where they’re focused on dementia research. We’re going to look at early on in the spectrum how we can actually treat the brain in a way that lead to reversal of dementia. I think we’re really seeing exciting things happening.

We’re working with one of the urologists who’s just fanatic about functional medicine and nutrition, and we’re doing a whole nutritional intervention with functional medicine to reverse prostate cancer. We’re actually looking at sophisticated genetic tests in prostate cancer because you can actually see changes quickly. You can do biopsies before and after, so you can really get tissue easily, and it’s a wonderful way to actually look at the effect of these interventions.

There’s so much happening, and I wish I had 10 of me because we could do so much. It really is a powerful shift in the paradigm. In fact, Toby Cosgrove, who’s the head of Cleveland Clinic, has seen the future and understands that this is the future of treating chronic disease and has brought it not in the periphery as an add-on to their services, but really into the center. In fact, we are literally in the heart of Cleveland Clinic. We are in the main building, right in the heart, and we’ve grown so fast that we have 1500 people on the waiting list. Last week I saw four doctors in my practice—two deans of medical schools, two chairmen of departments of institutes—that are coming to see me as patients.

Chris Kresser: Right.

Mark Hyman, MD: When the deans of medical schools and the heads of institutes from major centers are starting to understand that they need help and they’re actually asking for care from functional medicine, then we’re seeing real changes.

Chris Kresser: Yeah. That’s exactly been my experience—on a smaller scale, definitely! I have to say 20 to 30 percent of my patients are physicians or healthcare practitioners from the conventional model. They’re athletes and people who are really in prominent positions in many different fields who are becoming aware of this work. It makes sense to them! It’s kind of a no-brainer, really.

Mark Hyman, MD: Yeah, it’s really true.

Chris Kresser: This is kind of a little bit of a tangent, but I’m a research nerd, as you know, so I think about these things! Functional medicine, one of the principles is it’s individualized, right?

Mark Hyman, MD: Yeah.

Chris Kresser: We don’t necessarily give the same treatment to the same patient even if they have the same condition because we know that for one person with depression could be an inflammatory disorder, but for another person it may actually be more situational and related to what’s happening in their life, or maybe it’s related to the gut-brain connection and the gut microbiota. When you’re designing a study to test functional medicine, how do you take those individual differences into account? Or are we at the point where we can’t really do that yet and it’s just one step at a time?

Mark Hyman, MD: I think we absolutely can and do. I mean, this is what we do as practitioners of functional medicine. We treat everybody differently based on what their problem is. I always give the example of depression. If someone comes in and they’re hopeless and they’re helpless and they have no interest in daily life or sex or they don’t want to eat or can’t sleep, you have depression. Well, that’s just a name that we give people who have those symptoms, but then we can figure out what the cause is for each person. In one person it may be because they’re eating gluten and have developed an autoimmune thyroid condition called Hashimoto’s. Another person may need thyroid replacement. In another person, it may be because they have been taking an acid blocker for 10 years and have B12 deficiency, or because they have vitamin D deficiency from living in the Northwest or it’s winter, or because they have taken antibiotics which altered their gut flora and created inflammation, or because they eat sushi and have mercury poisoning, or hate fish and have omega-3 deficiency, or maybe eat a lot of sugar and have prediabetes. In each one of those patients, you need to figure out what their issue is that’s causing their depression. It’s not like everybody gets an antidepressant. You have to figure out an individual personalized approach to every patient.

Chris Kresser: Right, so how do you approach that in research? That’s what I’m wondering.

Mark Hyman, MD: How do you approach it in research?

Chris Kresser: Yeah, like doing research on functional medicine.

Mark Hyman, MD: In our studies, what we’re designing an approach. We’re studying an approach, not a particular therapy. We’re not saying, “Well, let’s study CoQ10 in X,” or “Let’s study this diet in this.” We’re actually saying, “Everybody who comes in is going to get a personalized evaluation, personalized diagnostics, and based on what we find, we’re going to customize a treatment.” It’s like a black box. They’re going to come into the box, they’re going to get treated, they’re going to go out, and then we see who gets better.

Chris Kresser: Right.

Mark Hyman, MD: Then people go, “Well, how do you know what worked? What’s going on? How do you prove it?” and the truth is that we won’t know exactly what it is. We’re just testing the method, and then we can go back and start to look at mechanisms and what’s working and what’s affecting it. I think it’s really the approach.

Chris Kresser: Is there a control group that gets standard care for that, or at this point, is it just testing the functional method?

Mark Hyman, MD: Well, we’re testing the approach and looking at how these different approaches, compared to conventional therapy, work or not. We’re going to take people and an autoimmune disease or with migraines or diabetes and we’re going to randomize them to either a conventional approach or functional medicine, and then we’re going to see how we do.

Chris Kresser: Well, see, that makes perfect sense to me, and this is where I think the whole RCT thing has gotten a little out of control. It’s been a tremendous development in research, and it has really changed medicine in a lot of positive ways, but when it comes down to it, patients have a choice to make in terms of what kind of care they get, right? They can either go see a functional medicine doctor or they can see a conventional doctor. That’s really what it boils down to. In the end, it doesn’t matter as much whether it was this intervention or that intervention that made the difference in the functional approach because the decision that they have to make—and the decision from a public policy perspective that needs to be made—is what is the model of medicine that’s going to produce the best results.

Mark Hyman, MD: Exactly. Then we can dig into what the issues are or what we want to do, but I think it’s really important to get the initial comparison and saying, “What are the benefits?” What we’re looking at are what I call the “holy shit studies” instead of the “so what? studies.” In other words, it’s not like, “Oh, well, you got a person a little better,” it’s like, “Oh, you fixed a problem that nobody else could fix.”

Chris Kresser: Right, that we’re spending hundreds of billions a year treating.

Mark Hyman, MD: We’re taking people and getting them off insulin. That just doesn’t happen in medicine. People get progressively more medications. We “manage” their diabetes. We don’t “fix” their diabetes.

Chris Kresser: Yeah.

Mark Hyman, MD: With migraines, we “manage” their condition, and often there are patients who are very resistant to treatment, and we’re going to take the hardest cases who are the ones that no one else really would want to do, and that’s a problem.

Chris Kresser: Yeah. I think that’s right because the RCT model, in some ways it’s antithetical to individualized care because it’s trying to remove everything from the process except for the explicit effects of a particular intervention in a group of people.

Mark Hyman, MD: Right.

Chris Kresser: In fact, really the more accurate way of talking about placebo is the sum total of the effects of the interaction that happens between the clinician and the patient.

Mark Hyman, MD: Right.

Chris Kresser: Up until the advent of randomized clinical trials, that was seen as something to be celebrated and encouraged and a crucial part of medicine, and in some ways, RCTs have made that kind of a bad word, as if we can remove ourselves as clinicians from the interaction with the patient.

Mark Hyman, MD: Right. Of course, it’s not a bad thing!

Chris Kresser: Yeah, so it’s really cool to hear what you’re doing there, Mark. It’s inspiring and I’m so glad to know that this is happening. A lot has changed just even in the past few years.

Mark Hyman, MD: It’s unbelievable.

Future Developments in the Delivery of Care

Chris Kresser: Yeah, it’s really exciting. What future developments in medicine or the delivery of care are you most excited about at this point? If we had a crystal ball… I mean, so much has changed, as we just said, in the last five years. Let’s say we’re having this conversation five years from now, what do you think we’ll be looking back on and celebrating and talking about?

Mark Hyman, MD: You know what’s exciting to me, Chris, is I think that we’re going to rethink not just what we’re doing, but how we’re doing it, the delivery of care. I think one of the challenges is that we have very centralized, top-down medicine. What’s the uberization of medicine look like? How do we connect together information, people, services, products that empower people to take things into their own hands and what we call disrupt or disintermediate the medical profession? We see this with Airbnb. We’re cutting out the middleman!

Chris Kresser: Yeah!

Mark Hyman, MD: And there’s an access issue, and I think we can do that with scalable solutions. I can imagine a future where functional medicine is built into a bioinformatic system which analyzes your history, medical history, analyzes lab tests that can be done by yourself at a local pharmacy or anywhere or maybe a kit that’s sent to your home. That data gets put into a system. It’s driven through an artificial intelligence decision support system. It spits out guidelines and recommendations for you to do. You find other people to do it with in your community. You learn how to actually connect the resources that are around you that link everything together. I mean, Uber didn’t invent anything new; it just linked together all sorts of resources to make things easy, and that can happen in medicine to help people change their lifestyle and behavior. It can link people in the community who want to get healthy together, who want to learn how to shop and cook and do all kinds of things.

I think we’re going to see future healthcare without walls. We’re going to see folks like you and me only dealing with tertiary care, really very severe problems that require a different level of expertise, that most problems will be able to be dealt with by people by themselves at home without healthcare providers or maybe health coaches or maybe online groups or whatever the Facebook of healthcare is. That’s where I think we’re going that’s going to change the face of medicine, and I think functional medicine is the operating system that can drive that so that people get the most powerful change in their biology.

Chris Kresser: Yeah, that’s really exciting. Lest people think that this is a totally sci-fi, unrealistic vision, I’ve seen research showing that apps where you take a picture of a skin lesion or rash and upload it to this database are more accurate in diagnosing correctly the skin problem than going to a dermatologist in some cases!

Mark Hyman, MD: Yeah!

Chris Kresser: I don’t think we’re very far away from many of the things that you just talked about.

Mark Hyman, MD: Exactly. No, we’re not. Then maybe it’ll be linked to telemedicine, where people can link to you and me via telemedicine and we can do a consult and guide them. It makes it super easy, yeah.

Chris Kresser: That, as you alluded to earlier, will hopefully solve the access issue. Right now functional medicine, at least in the kind of private one-on-one scenario, is really only for upper-middle-class people and above. We’re looking at offering group visits, both in person and video using video conferencing software, and integrating some of these algorithms and delivering content from ebooks and audio and video that can complement the courses.

Mark Hyman, MD: Yeah.

Chris Kresser: It’s exciting to see what’s possible. And I think not only in our lifetimes, but really in the next five to ten years we could see this stuff really make a huge dent in how things are done.

Mark Hyman, MD: It’s pretty exciting.

Mark’s New Book

Chris Kresser: Speaking of exciting, you just published a new book two days ago, I think, and it is, what… book number 10? Is that right?

Mark Hyman, MD: No, actually it’s like 13.

Chris Kresser: Thirteen?! Wow! That’s amazing. I can’t keep up.

Mark Hyman, MD: Maybe it’s 12. I don’t know. I’m losing count.

Chris Kresser: This book is all about fat. What made you decide to write about fat?

Mark Hyman, MD: I’d been telling the sugar story for a while, and then I realized it’s pretty clear that we now know that sugar is the driver of most chronic disease, but no one has really told the story of fat, which is when you stop eating sugar, what do you eat? Well, you have to eat something. You can’t just eat steak all day long. You need fat.

Chris Kresser: Some of my listeners might beg to differ!

Mark Hyman, MD: By the way, for those of you who don’t know this, when you eat too much protein, it actually turns to sugar in your body through a process called gluconeogenesis, so it actually can spike insulin and do all those things if you’re eating excess amount of protein. That’s another story.

Chris Kresser: That’s the next book.

Mark Hyman, MD: That’s the next book! But I realized that no one really kind of dug into the slippery science of fat and separated, well, I say, fat from fiction and actually kind of helped us emerge from this low-fat craze that we’ve been in for 35 years that’s caused this epidemic of obesity and diabetes, so I decided to tackle fat. It’s the most difficult book I’ve written because the controversies are so deep and the paradigm shift is so big, but I felt that I really needed to go into it.

The book is really a detailed analysis of the science of how we got in this mess, what we know about fat today, and blowing up two of the biggest myths, which are that fat makes you fat and that fat causes heart disease. Then it lays out a step-by-step program for people to learn how to include the right fats in their diet, how to increase fat without getting into trouble, for example, like eating refined omega-6 oils or having trans fats, and actually eating a diet that is overall well balanced and healthy.

Chris Kresser: I know that if I look back at just even five years ago, some of my beliefs about food and nutrition have changed significantly since then, and I hope they continue to change because it means I’m still learning and growing. I know that in the past you maybe leaned more towards a lower-fat kind of approach, and I’m just curious how your transition to this… maybe it’s not so new for you, but maybe for some people that in the past were familiar with your work, how that’s been received by some of your colleagues in the lower-fat, plant-based world, and what that’s been like for you. I’m just curious.

Mark Hyman, MD: Well, I wrote Ultraprevention 15 years ago, and in that book I wrote fat is not a four-letter word because it was becoming clear even then, in the heyday of the low-fat era, that there were benefits to fat and that we shouldn’t all be low fat. So I’ve been talking about this for a long time, although my thinking has evolved and I realize that I though saturated fat was evil, and now I realize that based on the science, I don’t think it’s so bad. I don’t know if it’s a health food, but I think if I had to choose between butter and a bagel, I would definitely choose the butter, where I used to choose the bagel.

Chris Kresser: Yeah.

Mark Hyman, MD: I think that’s really shifted for me. I used to be a vegetarian. I used to eat low fat. I used to eat a ton of pasta. I thought pasta was a health food. And when I look at my own health and my own body, it’s just stunning to see the difference. I’m just amazed. I see pictures of myself when I was in my 30s and what my body looked like, and I was more flabby and just not as fit. Now with less exercise, I’m more muscular and have more levels of fitness than I did. It’s pretty fascinating to see what happens. I lost 15 pounds, and my waistline went down two inches. I feel more fit and lean at 56 than I did when I was younger, and I thought I was eating a healthy diet. It wasn’t like I was eating junk food. I never had soda. I never had processed food. I never had junk food. I ate tons of fruits and vegetables, but I did tend to eat more starches and more refined carbs and more pasta and more rice and more whole grains and more beans. Now I don’t not eat any of those things. I sort of joke about something called the “pegan” diet because I was once on a panel with my friend Joel Kahn, who’s a vegetarian cardiologist and a vegan, and my friend Frank Lipman, who’s a doctor and on the paleo end, and I’m like, “I’m in the middle here. I must be a pegan.” I sort of joked about it, and then I began to think, “Well, what is a pegan? What are the principles that are in common?” In fact, I realized there are a lot of principles that are in common between vegans and paleo if they just kind of stopped for a minute and stopped being religious and started being curious.

Chris Kresser: Yeah.

Mark Hyman, MD: I think that the concepts of a very-low-glycemic diet, of an unprocessed whole foods diet, of a diet rich in fruits and vegetables that are colorful and full of antioxidants, a diet that’s low in antibiotics, hormones, or pesticides, that’s non-GMO, a diet that’s absent of artificial sweeteners, additives, and ingredients, a diet that is actually higher in good quality fats, a diet that is very, very low glycemic. These are standard principles. Even a diet that’s not having any dairy in it is common to both, and having good quality proteins, whether they’re plant based or animal based, I mean, that’s the biggest difference.

And then grains, I think there’s a view and my perspective is that some amount of grains can be OK for some people. I think gluten grains are probably the least healthy, and I think if you have things like buckwheat or quinoa or teff or other things that are what I call “funny foods,” they actually can be OK for some people.

I think we really have to look at what’s that person’s individual health issue, what’s their genetics, and there’s a whole field of nutrigenetics. You and I, Chris, have talked about this, that there isn’t a one-size-fits-all, and some people need more or less fat.

Chris Kresser: Yeah.

Mark Hyman, MD: We’re now just beginning to understand how that might work. I think it’s really just being curious, not religious, about the whole thing.

Chris Kresser: Yeah, and eating real food.

Mark Hyman, MD: Yeah.

Chris Kresser: That’s so much of it, what it comes down to. We’ve shared a few meals together, and if you looked at both of our plates, you’d have a hard time knowing who was the “paleo” guy and who was the other guy! People want to make it into a black-and-white thing and it’s really not.

Mark Hyman, MD: Mm-hmm.

Chris Kresser: Was there anything in the process of researching and writing the book that just totally surprised you, you weren’t expecting, or it was kind of out of left field? You just did the Fat Summit a couple of months back, and you had people from all over the spectrum talking about fat. You really put yourself in that position of being in the middle, the mediator, so I’m curious. This is what you do, it seems like, when you get into a topic, you really dive deeply in and look at all the different sides of it, so I’m just curious to know anything that came out of that experience that is worth sharing.

Mark Hyman, MD: Well, I try not to have a preconceived notion of things and just try to listen to perspectives and combine that with common sense and some sense of what I call the sniff test, you know?

Chris Kresser: Yeah.

Mark Hyman, MD: Like, does this actually make sense? Gee, if we’re being told to eat 20 percent of our calories as soybean oil, is that something we’ve done for millions or years or has that just happened in the last hundred years? And if that’s so, is that a good idea? Probably not. That’s what I call the sniff test!

I think the thing that really struck me as I began to do the research was just how much fat we probably should be eating and how 40, 50, 60-percent-fat diets actually can be very healthy and correct a lot of the problems that are affecting people, including weight gain and particularly metabolic syndrome or type 2 diabetes. Looking at the studies, I was sort of amazed to see how we can really impact those conditions through higher-fat diets. I had a patient, she was prediabetic, overweight, struggled to lose weight for years, had cholesterol of 300 and triglycerides of almost 300, 200-something. She was trying to eat a basically healthy, whole-foods diet. It just wasn’t working. And I said, “Well, why don’t we try a ketogenic diet? Why don’t we try, like, a 70-percent-fat diet. I want you to have coconut butter and grass-fed butter, saturated fats. Just try it for, like, two months and let’s test your blood and see what happens.” She called me back. She was like, “Oh, my God, Mark. My weight went down 20 pounds for the first time in 30 years. My cholesterol dropped a hundred points. My triglycerides dropped 200 points.” I was like, “Your cholesterol dropped a hundred points having butter and coconut butter?!”

Chris Kresser: Yeah.

Mark Hyman, MD: Even for someone like me, I’d been so indoctrinated, like the rest of us in this culture, that saturated fat causes abnormal cholesterol, that I just… The other thing that was shocking to me is that I thought that saturated fat was bad because it raised saturated fat in your blood and that actually we know that high saturated fat levels in your blood are dangerous and cause heart disease. What really shocked me was learning that actually it’s the sugar and refined carbs that cause your body to produce saturated fat in your liver. It’s not saturated fat that you eat that causes high levels of saturated fat in your blood. It’s the carbs. That was kind of an eye opener for me.

The other eye-opener was that you can use high-fat diets to reverse fatty liver, which affects 90 million people, and that MCT oil, which is a derivative of coconut oil, that we can actually use that to reverse fatty liver, which is pretty amazing.

Chris Kresser: Yeah.

Mark Hyman, MD: There are so many things I learned. It was really eye opening, and I write all about it in the book.

Chris Kresser: Yeah, which I highly recommend. Nobody has really done this the way that you’ve done it so far, just to trace the history of it and talk about fat from the perspective of summarizing all the most recent research and how it can help. I think it’s a really balanced view on the topic that’s not the super-dogmatic approach that a lot of people take. There are tons of books about ketogenic and low-carb diets, there are tons of books about low-fat diets, but for someone who just wants to get a kind of rational, well-researched, balanced view on the role of fat in the diet, I can’t recommend this book highly enough. If you’ve ever read any of Mark’s other books, you know what you’re going to be in for. They’re always very well written and super practical and easy to implement, so definitely get out there and check it out.

Mark, thanks so much for coming on the show. It’s been a pleasure to talk to you. And thank you for all of your contributions to functional medicine and moving this forward. I know as a practitioner myself, it’s really exciting and inspiring to see what you’re doing and to know that we’re part of this movement and really transforming the way that healthcare is delivered.

Mark Hyman, MD: Well, thank you, Chris. It’s been amazing to follow you as well. I think you’re one of the few people out there who are really digging into the research, are thoughtful, and report on ways that are clear, accessible, and I personally learn a lot from you, so thank you for what you do, too.

Chris Kresser: I appreciate that, Mark, and I look forward to seeing you and our paths crossing again at the next… whenever that happens.

Mark Hyman, MD: Absolutely.

Chris Kresser: Good luck with the book, and let’s do this again soon.

Mark Hyman, MD: OK, Chris. Thank you so much.

Chris Kresser: All right, take care.

Mark Hyman, MD: Take care.