[Transcript] – Is It Possible To Be Extremely Active and Eat A Low Carbohydrate Diet?

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Podcast from:  https://bengreenfieldfitness.com/podcast/low-carb-ketogenic-diet-podcasts/exercise-on-low-carbohydrate-diet/

[00:00] About Dr. Peter Attia

[02:01] What is War on Insulin?

[05:42] Dr. Attia's Self-Experimentation

[13:35] Dr. Attia's Exercise Routine

[31:50] Exercise with Low Carbohydrates

[36:07] Research on Ketogenic Diets & Exercise

[43:42] Dr. Attia's Diet Style

[53:05] The Best Athletes in Ketogenic Diets

[59:34] Supplementing in a Ketogenic Diet

[1:04:15] Regarding the Thyroid

[1:08:54] End of the Podcast

Ben:  Hey folks, it's Ben Greenfield here, and we have certainly been focusing lately on what to eat during exercise here on the show, and today, we're going to take that another step further, and talk with Dr. Peter Attia, who happens to be among many other things, a physician and a relentless self-experimenter who has basically spent the last few years seeing how the body responds to specific nutritional protocols that we'll be talking about today on this show, and one of the main areas that we are going to delve into is low-carbohydrate eating, ketogenic diet and how these jive with a very active lifestyle and a high amount of exercise.  Dr. Attia actually received his medical degree from Stanford.  He also holds degrees in Mechanical Engineering and Applied Mathematics.  He did a surgical training at Johns Hopkins Hospital in Baltimore, and he has been a consultant with McKinsey & Company as well as an engineer, a calculus teacher, and he's written many medical and research papers.  He actually has a website now called War on Insulin.  That's at waroninsulin.com, and we'll be talking a little bit about that website as well.  Now Peter, first of all, thank you for coming on the call today.

Dr. Attia:  Thanks very much, Ben.  It's a pleasure.

Ben:  You actually have a pretty cool story.  I read about it a little bit on your site, but I think that's a perfect place to start here just because you have such a varied background, and it's kind of interesting at how you came to start this website waroninsulin.com and what you're doing with that.  So, can you tell the audience a little bit about how and why you started waroninsulin.com and what exactly it is that you're trying to achieve with that?

Dr. Attia:  Sure. It's funny that technically if I really would be accurate, I would have called it the War on Insulin Resistance, but that just didn't seem catchy enough, so it stands to be called the War on Insulin, although I would like to clarify that I'm not morally opposed to the beta cell which is part of the pancreas which makes it.  So, really, this is all about fighting insulin resistance.  We'll talk a little bit more about that later, but as you said, the blog which has not been around long, only about four months, started basically because I've been e-mailing a whole bunch of friends and family who themselves have been fast passing it on to their friends and their family, and some point, people said you should just probably start organizing this into a blog as opposed to a series of e-mails that get forwarded around.  So, that's why I started the blog, but what the e-mails were all about was, as you pointed out, the self-experiment.  It started about two years ago in myself, and it led me to go beyond just self-experimentation and try to better understand the science of nutrition, and that's what I write about, and basically, the war on insulin is about four things.  One is nutrition science is really lousy.  I mean it's shockingly lousy, in terms of the hierarchy of science and how the scientific method is applied to asking questions, and as a result of that, I came to realize that most of what I was taught and most of what I had believed was actually incorrect, with respect to nutrition.

Ben:  You mean what you were taught in medical school?

Dr. Attia:  Exactly, what I was taught at the best medical schools and residences in the country, and in the second thing I sort of want to communicate that pending really, really, really good science, the best data available today actually suggest to me that most people, probably about two thirds of people, really benefit from a diet where the total insulin load in their body is reduced, and that's done primarily through reducing the causative agent of insulin which is carbohydrates.  The third thing I try to get across to people is that it's really important to learn to self-experiment because, at the end of the day, what really matters the most is what your body does and how your body responds, and because we're not a completely homogeneous population, there are going to be differences between people, and it's really important for people to understand what works best for them, but they need to understand how to do an experiment on themselves, how to change one herb a time, for example.  And then the final thing I try to get across, which is a nuanced point that I don't know that everybody appreciates, but hopefully I'll be able to get it across in time, is to differentiate between optimization and maximization.

So, we live in a multivariate world, and it's very difficult to maximize everything.  It's very hard to say I want to job that pays me the most money and the most job security, and it makes me the happiest.  It's possible and there's probably some people living that, but for most people, we optimize rather than try to maximize.  We say look, the single most important thing to me is being really happy and fulfilled in my job, even if it means making a little bit less money and even if it means perhaps not having the same amount of job security, and there are other people who say no.  The most important thing is to make the most money possible, and I don't care what I'm doing.  And there's no judgment between us, I just want people to understand that the same thing is true in health, right?  If you're optimizing for minimization of disease risk, it won't necessarily mean that it's giving you the maximum athletic performance and vice versa.  So, those are the four things I try to get across.

Ben:  Okay, so you talked about the self-experimentation in the series of emails and basically an experiment on yourself in the realm of nutrition that you did, and I'd like to hear what exactly it was that you were self-experimenting with and why?

Dr. Attia:  Well, I've been active my whole life.  While the sport has changed throughout my life, I've always pursued things with only one speed which tends to be full out.  So, growing up, boxing and martial arts are really my sports, and do those things about six hours a day actually, and then today in life, my main things are swimming and cycling with a decent amount of weight training as well, but something happened once I hit my 30s, which is basically my genetics caught up with me.  It would seem I really was demonstrating all of the telltale signs of insulin resistance, so increasing out of positivity.  I was getting fatter and my waist was getting bigger.  My triglycerides were getting higher.  My high-density lipoprotein cholesterol was getting lower.  By objective metrics, I was becoming more insulin-resistant when you do these tests that you can measure insulin and glucose levels in response to challenges.  I was just approaching that clip, and this was particularly vexing because I was exercising three to four hours a day, and it was probably in the summer to fall of 2009 that my wife jokingly, although she denies it to this day that she said this, but I remember it clear as day.  She said you really ought to try to be a little less not thin, and at that point, I'm frustrated too, and I'd like to be less not thin, but I don't know what else to do because.  I don't eat much junk food.  I kind of eat that iconic athlete's diet.  I eat a lot of complex carbohydrates, lean protein, very little saturated fat.  I don't eat sugary stuff, at least I didn't think I was, and we'll come back to that in a second, and I can't exercise more because there's only 168 hours in a week, and I don't really want to spend more than 26 of them exercising.

Ben:  Which is still a lot of exercise.

Dr. Attia:  Which is, yeah absolutely.  So, that took my down this path, and I decided to do an experiment, and the first thing I decided to do was figure out how much sucrose and high-fructose corn syrup was in my diet, and just ask the question, what would happen if I made no change in anything I was doing except removing sucrose and high-fructose corn syrup?  And like I said, I wasn't the guy out there eating candy bars and putting white powder in my coffee, so I had to look for those more sinister places where the stuff showed up, but it showed up in most of the cereals I was eating.  It showed up in the yogurts I was eating, it showed up in the pasta sauce, it showed up in all these places that I was kind of shocked to realize ingredient number two or three always seem to be high-fructose corn syrup.

Ben:  Now when you say sucrose, that's basically table sugar, right?

Dr. Attia:  Exactly, sucrose is table sugar and it's the white powder, and also you can find it in beet sugar, cane sugar, etcetera, but from a molecular standpoint, it's a glucose-fructose mixture at a one-to-one ratio, 50-50, whereas high-fructose corn syrup.  The slightly difference, it's 55% fructose, 45% glucose.  There's a big hoopla about which one is better, which one's worse.  I completely agree with Robusta on this.  They are literally the same thing.  The moment your gut hydrolyzes the fructose-glucose bond, your body knows no difference.  Sucrose and high-fructose corn syrup are identical to me, and just removing this agent, these two agents, from my diet had a pretty impressive effect.  Again, I wasn't restricting carbohydrates in any way, shape or form, it just meant I had to go out of my way to eat better food, so it really cleaned up my diet because if I wanted to eat spaghetti.  I now had to get the actual tomatoes myself, cut them up, use my own garlic and make my own sauce.  I couldn't just get that Prego out of a jar, and so after about six months, I went from being about 200 pounds at 25% body fat by Dexa, which again is a BMI of about 30, so I was on the border of overweight to obese, but given how active I was, it seems shocking that I could be that big, and I think, and this is all documented on my blog.  I don't have the numbers in front of me, I think I got down to about a hundred and maybe, 85 pounds, and I probably reduced my body fat to 17, 18%, something in that range.  So, I  had a pretty impressive impact just making that change, and of course, the other places where the impact was most noted was on my triglyceride level, my fats and triglyceride level fell by about half, and my HDL started to rise.  So, I realized I was on to something good, if you will.

Ben:  And I was just with those two changes, just eliminating high-fructose corn syrup and sucrose?

Dr. Attia:  Exactly, that was getting rid of every gram of high-fructose corn syrup and sucrose in my diet, and you know?  The other thing I did, sorry I forgot to mention, is I also eliminated fruit juice, so liquid fructose, I took out of my diet as well, but I didn't restrict fruits.  I didn't restrict vegetables, I didn't restrict starches, but anyone who's done what I'm describing will appreciate that your choices go way down.  So, while I still ate bread, there's only two variants of bread I could find that didn't have sugar in them.  So, while I still ate cereal, I was eating steel cut oats and instead of putting brown sugar, I would just put some raisins in and that sort of thing to go.  In I guess typical Peter Attia fashion, I like to be in the amount of acceleration and wanted to push down a little bit harder on the pedal.  So, the next thing I did was gradually start to scale back on the amount of carbohydrates I was consuming, and again, the improvements continued, and the final step in this experiment occurred about a year ago when I decided to do a 12-week experiment, entering what we call nutritional ketosis.  And I'm not sure if folks would be familiar exactly what that is, because the term ketosis generates a lot of confusion.

A lot of people confuse nutritional ketosis with something called diabetic ketoacidosis, and the two, I like to tell people they have about as much in common as say a house fire and a fireplace.  They both involve fire, but one is a completely controlled good thing that heats your house, the other is a completely out of control thing that burns things down, and so nutritional ketosis is a state where you are at a much lower level of ketone production.  You don't have any acidosis, but you've switched your body's metabolism over from that of glycogen metabolism primarily, and glucose being the primary substrate for the brain, into a state where your liver is now breaking down your own fat to make these things called ketones and those ketones even feed your brain.  So, I did this experiment for 12 weeks, and at the end of the 12-week period, I was actually sufficiently pleased with many of the dimensions along which I'd improved that I just never went back, and I do suspect at some point, and I'm even contemplating this summer, going back to introducing some carbohydrates into my diet for a different experiment that I'd like to do.  But nevertheless, I found this to be a really interesting place to be, and again, in the spirit of optimization versus maximization, I would say that ketosis has cost me a couple of things, and we can talk about that later in terms of some athletic performance, but it's also given me a lot of things, and everything in life is a balance, and I actually like what it's given me more than I missed what it's taken.

Ben:  Okay, gotcha.  So, I want to delve into how it is that you actually achieved ketosis and what your diet actually looked like, but before we go into that, you mentioned that you do some swimming, you do some cycling and you do some weight training, but you also mentioned that you exercise, in some cases, above 25 hours a week.  So, can you walk us through what a typical week of exercise looks like for you because I do know, and I've heard this before from people that, say eating a low amount of carbohydrates is maybe easy enough if you're fairly sedentary or not living like an Ironman triathlete or something like that, but that once you start to exercise, a lot of it becomes impossible.  So, what were you doing when it comes to physical activity as you went through this self-experimentation protocol which, from what I understand, you're still doing?

Dr. Attia:  You know, it varies by season.  In the winter, I'm really focusing most of my training towards my swimming goals, and in the summer, it's focused more towards cycling.  But as a general rule, a typical week will have three sessions in the weight room where I'm doing pretty high intensity work.  Each of those sessions will be ninety minutes to two hours and involves most of the Olympic lifts, and obviously depending on the cycle, sometimes we're doing five-five-five, sometimes it's five-three-one.  Sometimes it's just Tabata, but the point is it's always very intense, and it's all of the Olympic lifts and the power lifts and a number of accessory lifts to go with that.  I'm always running the heart rate monitor in the weight room because very little of what I'm doing in there is not demanding enough that I want to be thoughtful about what zone do I want to be in for this session versus that?

So, it's a pretty intense in the weight room, and it's pretty consistent year-round, with the exception of around competition where I will taper off for two weeks and try to stay a little fresh.  In the winter, I will probably only spend two days a week on my bicycle, and because I live in San Diego, I'll do a longish ride on a Sunday, and that long ride on Sunday might be anywhere from fifty to a hundred miles, and then I'll probably do one ride indoors on the trainer which is more of what I call an FTP ride, so a Functional Threshold Power ride.  I do a threshold test, usually once a week.  And then in the winter, I would spend probably five to six days a week in the swimming pool.  In the summer, that just flips a little bit, and the weight training is about the same.  The swimming goes down to four days a week and cycling goes up to four days a week, and so the bulk of the hours are probably spent on the bicycle.  Although in the winter, those swim workouts get a little bit longer.  So, that's a typical week in the life for me, in terms of what gets done.

Ben:  Gotcha, and I noticed that you posted a video of your workout, and it’s pretty nuts.  It's tire flips and jumping pull-ups and cleans and snatches and heavy squats and some pretty serious stuff, over and above what most people really even do in the weight room and definitely not what most would consider a “fat-burning intensity”.  You have a video of that in your website, and I'll make sure I direct people to that in the show notes, so they can check out the video if they want to see you prove that you actually are working out really hard.  You also swam across the Catalina Channel down there in California, and I saw a video of that, and I also noted that you're doing one hundred plus mile rides.  So, folks, Peter's exercising in a fairly high level.

Dr. Attia:  You brought up a great point which is that it’s kind of always aggravates me when people say well, sure, you can cut our carbohydrates, but then you can't do anything, and I'm not going to for a moment suggest that eliminating carbohydrates through the way to maximize physical performance.  I think a point I like to make, and the reason I posted that video that you mention is to illustrate the point that you get your body to adapt to doing these things, and there's trade-offs associated with doing it.  Now let's be clear, when I first entered ketosis, I didn't do a very good job of adapting, meaning there were a few things, and we'll talk about this in a moment 'cause I knew you wanted to get into the nuances of it, but there were a number of mistakes I was making during the first, probably four to eight weeks of my foray into ketosis, that actually really hurt my performance, and so I think a lot of the bad rap that folks give to carbohydrate restriction in some capacity with performance is one, they're not giving themselves enough time to adapt.  They sort of do it for a week, have some crappy work outs and say well, this is crazy.  And two, they're really missing out on some of the key supplemental things that you got to be able to do if you want to be at peak performance for a low-carbohydrate diet.

Ben:  Gotcha, so yeah we'll definitely hit on some of those mistakes and some of those supplements or supplementary activities that you're talking about here in a second, but going back to just the general eating pattern, when you're exercising for any given day during the week, especially on those exercise days, about how many carbohydrates are you eating and what does it generally look like?  If you want, you can just walk us through a sample day of eating and maybe quantify if you're going after a certain number of carbohydrates?

Dr. Attia:  Sure, so because I'm in ketosis, I spend a lot of time thinking about that number of carbohydrates and proteins.  In ketosis, and again I always want to preface by saying this, if someone just wants to reduce the amount of carbohydrates they want to consume, they don't need to get into the counting that I'm doing.  The reason I spend time in numerating how much carbohydrate and how much protein I consume is because ketosis is a very finicky place.  For reasons we don't entirely understand, it seems that for most people consuming more than about 40 to 50 tops grams of carbohydrate in a day is a level that prevents the liver from making enough ketones.  Secondly, consuming more than about 150 grams a day of protein or even a very large amount of protein in one meal, say 75 grams, is also sufficient to inhibit a paddock output of beta-hydroxybutyrate, which is the main ketone bodies are concerned with.

Ben:  Is that basically because the body's making carbohydrate out of the protein?

Dr. Attia:  It probably has to do with the fact that, as you said, the protein, whether it's directly making carbohydrates out of it through gluconeogenesis or it's just that protein is stimulating insulin.  I don't know that I know the answer entirely, but I've done a lot of experiments on myself.  In fact, in the past two weeks I've been doing, so many of my fingers are actually sore from poking myself so much.

Ben:  You mean with the blood glucose monitor?

Dr. Attia:  I'll do the blood glucose and the blood beta-hydroxybutyrate draws everyone to three hours, over the course of days and just monitor exactly how I'm eating is impacting, not just my glucose level, but more importantly my beta-hydroxybutyrate level.  So, with all that caveat said, a typical day for me would be the following.  Tomorrow morning, I will get up five o'clock in the water, so I will swim.  The only thing I'll consume before swimming is some MCT oil, so some medium-chain triglyceride, or I'll consume about 40 to 50 milliliters of that.

Ben:  And you do that instead of a coconut oil?

Dr. Attia:  Yeah, only because I actually like the taste of coconut oil a ton, and I cook with coconut, but coconut is only about 60% MCT, whereas when I buy a pure MCT, I know that I'm getting nothing more than that MCT oil.  But for folks who don't like the flavor of it or whatever, by all means, take a couple strips of coconut oil, and I think you're in pretty good shape.  And then I'll go and do a swim, that swim will be 90 minutes.  Thereafter, I'll have my morning, what I call my fat shake, which is a shake that has about eight ounces of high fat or heavy fat, 35% fat cream, coupled with a little bit of sugar-free almond milk, probably about 30 grams of whey protein, maybe five to seven grams of glutamate and a couple of strawberries for some flavor and the consistency of a shake.  So, that's my serving of fruit per day, usually frozen strawberries, I'll put that shake.

So that shake provides, by calorie wise, about 80% of the calories come from fat, from a little bit of protein, and in particular, I specify in a post workout to use a little bit it of glutamate to sort of prevent catabolism that you're going to tend to see after a workout.  Mid-workout in the weight room but not in the pool, I'm also using a branched chain amino acid and in a dilute solution for the same sort of reason.  I won't eat, in the mid-morning, I'll probably have a lot of salt supplementation.  That's one of the really important things when you're under any form of carbohydrate restriction, but in particular, when you're in ketosis your body is really dumping salt.  Again, for reasons we don't exactly understand, although I've heard a lot of really interesting ideas on exactly what's happening and why the body just starts wasting sodium in a carbohydrate restriction, relative to the retention that typically goes on a high-carb diet, but regardless, I need more sodium, and I'll do that during the morning.

Ben:  Is that one?  You mentioned that you made some mistakes during your transition.  Is that something that you've learned through trial and error is that your body needs extra sodium?

Dr. Attia:  I would put that as one of the two really significant things I learned, which was sodium as a subset of a broader issue as electrolyte replenishment.  So, in order, it's sodium, magnesium, potassium with the big three you want to be thinking about, and a lot of people make that mistake.

Ben:  And is that why a lot of people who switch to a low-carb diet get dizzy and stuff like that, low blood pressure?

Dr. Attia:  I really believe it is.  I believe that when you go to a low-carb diet, if you fail to supplement sodium, especially if you're someone who had normal blood pressure to begin with, which I did, and not many people do, you're going to find yourself really light headed.  In fact, for four weeks, I could barely stand up.  I would stand up and need to really secure myself before I could even walk.  My wife really watching me undergo this experiment, she said you're categorically crazy.  Clearly this is not a good idea, why are you doing, and I said look, I'm stubborn and I said I was going to for 12 weeks, and I'll do it for 12 weeks, no matter what, which was kind of a dumb response.  What I should be doing is spending more time figuring out why I was feeling that way.  I finally did figure it out when Gary Taubes, who was a close friend of mine, introduced me to Steve Finney and Jeff Volek.  We'll probably talk about later today.  Steve and Jeff are probably two of the most erudite folks when it comes to ketogenic living, so Steve and Jeff were very quickly able to get me up to speed on all the mistakes I was making.  Almost within a two-day period, once I fixed those major issues I had was everything just remarkable.  And so, I feel bad for folks who don't have the Steve and Jeff of the world.  Fortunately, Steve and Jeff have written a great book, I know they've written a number of books, but the one that I consider the handbook for folks who want to experiment with ketosis.  It's called “The Art and Science of Low Carbohydrate Living”.

Ben:  Cool, I'll make sure I'll link to that in the show notes.  Okay, so you're up to like lunch time, in terms of what you're eating during the day?

Dr. Attia:  Yeah, lunch will typically be depending on if I'm at home or if I'm not.  I mean, if I'm on the road and all I can access is cheese, salami, that kind of stuff.  At home, I like eggs.  Sometimes I might even miss lunch, depending on what my workout schedule is, or I'll just eat some whipped cream which sounds kind of crazy, but I make my own whipped cream which is just high fat cream whipped.  And so that's a really efficient way for me to get my calories in, because you can take it in a large batch and you got it in the fridge.  I like a lot of coconut butter.  As you point out, coconut oil.  I like to eat straight as well.  Salads are pretty good for me, not because I have any particular affection for leafy vegetables, but it's a very convenient way for me to get fat.  So, for example, when out for lunch, I'll often find out a way to get a salad with some salmon or some steak on it, but I never let people bring me a dressing in a restaurant, learn virtually every salad dressing in a restaurant has either sugar in it and or a lot of Omega-6 polyunsaturated fats, so I'll just say bring me the salad with whatever the meat is, and then bring me my own olive oil, balsamic and lemon.  So, I'll make a dressing, but I'll make it with a lot more oil than most people would view as reasonable, but again, it's all a scheme for me to get more fat.  It is about, 90% of my calories come from fat over the day.

Ben:  Right, gotcha.  Okay.  So, what about when you're doing a long workout, like a bike ride, like a hundred-mile bike ride?  How are you setting up your fueling scenario for something like that?

Dr. Attia:  So, for anything over about 50 miles, I like to eat before I get on the bike as well.  So, I'll get up, maybe two hours before that ride, and I did my sort of go to breakfast, which is scrambled eggs and bacon, but I make the eggs a little different.  So, the first thing I do is to make six eggs.  I'll only eat four of the whites, or maybe not even that.  Maybe two or three of the whites, but I take out a lot of the protein, try to fatten up the omelet.  I add heavy fat cream to it as well, and then I fry it in coconut oil.  So, I'm basically eating a disproportionate amount of fat relative to the protein, and the reason I'm doing that is so at the time I get on my bike, my insulin levels are undetectable.  Now why do I want to do that?  The reason I want to be on my bike with undetectable insulin levels is when insulin levels are low, my body is prioritizing oxidation of fat.  When insulin levels are high, my body is prioritizing oxidation of glycogen.  So, I basically put a meal on board that sets me up to not have to earn much glycogen, except for the times when glycogen is absolutely required under peak exertion.  So, for me, anything over about a hundred sixty beats per minute, which for me is into zone four.

At that point, I do go after my muscle and hepatic glycogen, but anything below that, and again, a six-hour bike ride.  Your average heart rate is going to be between 140 and 145.  I'm spending the bulk of my time in a regime where I can access fat.  And then on the bike, I'm mostly consuming water.  There is a commercially available product that I do consume it is a starch.  It's called Super Starch.  It's made by a company called Generation UCAN, and this is a pretty remarkable product that we could spend just an hour talking about, but it's kind of interesting in that it is a starch that does not stimulate insulin.  And it's really, really slowly absorbed, so it's what I would call a time released form of glucose.  Well, it's basically inulin pectin which is plant glycogen, hydrothermally treated to make this unbelievably complex starch that is probably between 500 and 2,000 times larger and heavier than even maltodextrin.  So, as a result of that, and studies have shown this that this stuff takes a lot longer to break down, causes virtually no rise in insulin and maintain the normal blood level of glucose.  So, that's the thing you want to be fighting, you want to be fighting eating sugars and simple carbs on these rides where blood sugar goes up, insulin chases it, you turn out fat oxidation, and now you become dependent on that same glycogen that you're trying to chase.

Ben:  Right, I've actually spoken a little bit on the show before about the Super Starches and the very, very slow release of carbohydrates and low release of insulin that results from their consumption, and always talked about in the context of higher intensity racing, never in the context of training on a ketogenic diet, but it seems like something that makes a great deal of sense if you're wanting small doses of carbohydrate during something like a long, aerobic, four to six-hour training session, but you don't want to be taking in like these insulin-releasing fructose, maltodextrin type of gels.  So, that's what you do is just use, about how many calories do you use per hour?

Dr. Attia:  Very little, so on a one hundred-mile bike ride, I might only take in 30 to 50grams of Super Starch over the entire ride.  I also take little individual packets of cream cheese.  I love cream cheese, and so I know that's basically just pure fat, and I'll probably carry with me some almonds, cashews, walnuts, that kind of stuff.  But mostly, I'm getting virtually all my liquid in the form of just plain water, and when we stop and everyone else has to eat four sandwiches, at the halfway point, I squirt down a couple packs of cream cheese, a handful of nuts and chase it with some water.  So, there's an enormous metabolic efficiency that comes with this.  In fact, I wrote a post on this called the interplay between exercise and ketosis.  It's a two-part post, but I basically go through a three-day experiment of how exercise impacts ketosis on a bike ride, a hard swim and a hard lift.  And I comment a little bit about this actually.

Ben:  Now as far as looking at this from a scientific standpoint, you're doing all this exercise, you're eating very few carbohydrates, some people think in terms of calories rather than in terms of grams, but basically, what it sounds like is what you say, thirty to forty grams per day, or are you getting up any higher than?

Dr. Attia:  Yeah, I mean about 30 to 40, maybe less.  Maybe 20 to 30 grams a day of carbohydrate.  Yeah so we're talking about maybe a hundred to a hundred and fifty calories worth of carbohydrates.  Carbohydrates make up about 2% of my total caloric intake.

Ben:  Gotcha, which is very, very little, compared to most people who are exercising as much as you are.  So, what's the science behind that, Peter, in terms of how your body is able to accomplish so much exercise with so few carbohydrates?

Dr. Attia:  It's really one of what I call metabolic flexibility.  So, there are things that people dispute, there are things that people don't dispute.  One of the things that anybody who is serious, doesn't dispute is that insulin is probably the single most important hormone when it comes to fat metabolism, and when I say that metabolism, I mean both the oxidation a fat which we think about it as breaking down fat and the building up of fat.  So, when insulin levels are high, the body goes into an anabolic mode, and that's good and bad, right?  Anabolic just means we're building up, so high levels of insulin promote driving of amino acids into muscles, but it also promotes the driving of both fatty acids, and most importantly, carbohydrates into acetylcholine into fatty acids into fat cells.  When insulin levels are low, we find ourselves in a more catabolic state.  We're breaking down, and so the science behind what I'm doing is effectively this.  If I can put myself in a situation where I have relatively low levels of insulin, I can effectively have an unlimited access to my fact stores, and the way I try to explain this to people is anyone who's been out there and done a long activity and on a long run, hike, bike, whatever, they probably experienced bonking at some point, which is effectively a metabolic failure.  It's when you run out of fuel during exercise.  If you've been there, I certainly was there many times, especially during my long training swims.  I mean I remember doing typically a 10 to 14 mile training swim where, with two miles to go, I was just out of gas and out of fuel, and that last miles could hurt more than the first 12, but if you stick a step back and think about it, that's a totally unacceptable situation to be in because even the leanest person is carrying 60 to 100,000 calories worth of fat tissue in their body.

So why are we bonking, right?  It's like a fuel truck, driving on the road with an unlimited supply of gasoline behind it and running out of gas on the side of the road.  I mean it's really that's silly, and the reason it happens is because that fuel truck can't access the gasoline in the back of the tank.  It can only access the gasoline in the little tanks under the passenger door, right?  And that's what happens when people bonk.  People bonk because they're running out of glycogen.  Because they are dependent on glycogen, their brain is particularly dependent on glucose which we can only get from have had a glucose output or direct ingestion, and so when they run out of that, either because their livers run out of glycogen which is the common phenomenon that occurs after prolonged periods of exercise, and or they can't ingest glucose quickly enough, which is also common because with GI distress that associates with massive amounts of glucose ingestion, they run out of energy.  So, their brain shuts down, and the brain goes into a mode of protection which is we're done with this.  I need food, I need glucose now, and so I don't have that problem because I live in a state of ketosis.  My brain doesn't actually rely on glucose, so my brain is happy.  I just churn out constant amounts of ketones, and like I said, I've got 90,000 calories worth of fat in my body, so keep going.

Ben:  Now you mentioned a couple of doctors like Dr. Jeff Volek and Steve Finney, and I know that these guys are researchers, and in terms of the actual resources out there that's been conducted on people doing things like you're talking about exercising very long or very hard or both while eating low carbohydrate or no carbohydrate type of diet, what has been observed in the research in terms of what happens or the efficacy of a diet like this?  Just because I know, there are probably some people out there that are thinking oh yeah that's you, that's Peter, and what does the science say?

Dr. Attia:  I think there are a few studies that are worth looking at.  I think for me, the studies that I found most helpful, especially as I was contemplating entering ketosis.  There was a study done by Steve Finney back in the early 80s.  I think it was '83, and if I recall, I mean Steve at this point was probably a post-doc at MIT.  So, Steve also went to medical school Stanford.  We have that in common and then went off and started his medical residency in Boston, before deciding he wanted to actually step out, do his PhD, which he did at MIT, and I think he did a post-doc there, and while he did that, he did a number of studies looking at people in ketosis under high demand.  Now the bigger question I think is asking why?  Why would you even think to do this, and what motivated Steve to do this was really the Bellevue experiment, and sure you're familiar with it, but maybe your readers or listeners are in on it, might be worth spending a moment to do this.  So, there was a Harvard anthropologist, Stefansson, who spent, and this is not quite a hundred years ago, almost a hundred years ago.  He spent a significant amount of time living with the Inuit, and he wrote about this extensively.  So, he goes out to live north of the tree line, would be an Inuit, and they basically eat 90 to 94% of their calories in the form of fat.  Their eating blubber off both land and sea animals with a little bit of protein, but they have zero carbohydrate in their diet.  And he noticed that after a couple of weeks of feeling horrible, he started to feel really good, and he couldn't understand how this was possible, and they were carrying out the most strenuous activity he'd ever done in his life.

Well we lived with him for a number of years, and actually wrote about it, and when he came back to Harvard, he was mocked and his colleagues said this is impossible.  You're going to tell us that you were up there pulling sleds, building igloos, doing all this stuff, it's demanding, and you consume no carbohydrates, and he said, yeah.  So, they said well let's see if we can prove you wrong.  So, they put him in the Bellevue Hospital in New York for one year, along with one of his colleagues, and they replicate the conditions of what he underwent in the Arctic, and sure enough, not only did he survive, he really thrived, and he was able to demonstrate that a ketogenic diet is completely consistent and conducive with high performance, provided you do X, Y and Z, and he was the first guy to eliminate what X, Y and Z were, and that was you can't over consume protein and you must replenish sodium, and the way to the Inuit, of course, to do this was just through the salt water.  Most of the focus in cooking salt water, but they also learned, and it's amusing.  They weren't doing experiments, but they learned empirically, but when they ate the leanest cuts of meat, they felt the worst.  So, they figured this out long before Stefansson showed up.  So, the time Stefansson showed up, he observed that they would feed the lean cuts of meat to their animals and reserve the fattier pieces of meat for themselves, and so now fast forward 75 years, Steve Finney does a number of experiments, but the one that I found most interesting was a five-week study he did on highly trained cyclists, and I found this particularly relevant because this time last year, when I was getting ready to enter ketosis, I was also training for a really difficult bike trip, and what he did was he took great cyclists.  These are people who are far better than I am, and he did a difficult study as you do a two-week normalization period, where you observe normal eating habits, you get baseline measurements, and then he did a five-week intervention, and what I found most amazing in this study was that at a VO2 of 3.2 liters.  Now 3.2 liters, that means that these people are ingesting 3.2 liters of oxygen per minute at a cellular level.  That's quite a huge effort by the way.

Ben:  Yeah, it's going pretty hard.

Dr. Attia:  Yeah, so these guys correspond to about 60 to 65% of the VO2 Max.  These guys had a VO2 Max of about five to 5.1 liters per minute.  They had an RQ of 0.83.  Well that tells me these guys were really fit to begin with.  I know that for me, prior to ketosis, at a VO2 of 3.2 liters, my RQ was much higher.  That number RQ, of course, is the ratio of the CO2 you exhale to the oxygen you take in.  The higher that number, and that number tends to vary between 0.7 and one, the closer the number is to one, the more you are deriving your energy from glycogen, the closer that number is to 0.7, the more you are deriving your energy from fat.  So, it should be the goal of any athlete at a given VO2 and a given power output to have the lowest RQ possible.  That is what I mean by metabolic flexibility.  That means you have the ability to access fat or glycogen at a given power output, so these athletes started with an RQ of 0.83, and they went down over five weeks to an RQ of 0.72, and yet they had no change in exercise tolerance or VO2 Max.  I found that really interesting and I talked a lot with Steve about that.  The other studies I've looked at are studies that have been done by Jeff Volek and colleagues of Jeff Volek.

So, I think laymen did a study in 2005, if I remember correctly, and I'm blanking on the other one.  I think it was Kwan, circa 2007, 2008, but basically, these were studies that looked at the resistance training component of carbohydrate restriction, and could you or could you not assimilate lean tissue, because one of the biggest concerns I had was given that influence is an anabolic hormone, if you remove the anabolic hormone, sure that's great for fat breakdown, but I can't be affording to lose too much muscle.  Either I'm willing to get lose a little bit, in other words, if I'm going to lose five pounds, I'm willing to give up one pound of muscle and four pounds of that just because in cycling, it's all about your strength to weight ratio, but I don't want to lose five pounds of muscle.  And again, these folks showed that on a low-carb, high-fat diet, provided they were using resistance training, they were able to actually increase lean tissue while decreasing fat tissue.  This is enormous because there's a lot of studies out there that can show that just on a low-carb diet, you can lose overall body weight, but you tend to see people losing both lean tissue and fat tissue.  So, basically, what I took comfort in was that while no experiment is perfect, there are a number of experiments I saw that suggested I could maintain a reasonable semblance of athlete performance and lean tissue preservation while undergoing this diet.

Ben:  Interesting, so in terms of the maximum amount of carbohydrates that someone might be able to get away with if they wanted to stay ketogenic, and I know that you mention that protein would definitely be a consideration here as well, but as far as how much folks actually could get away with, is it that 30 to 40 grams that you're consuming on a daily basis, is it a little bit higher than that, that you would be able to get away with and still stay in a ketogenic state, and along with that, how much do you need to limit protein so that you don't shut down being in a ketogenic state?

Dr. Attia:  Well, it's an interesting question, and so just to be clear, you're asking about a ketogenic state, not in general, correct?

Ben:  Yeah, like a frequently exercising individual, someone doing things like you're doing or someone who's like trying for triathlon, they're trying to maybe start looking at labels, start looking at nutritiondata.com or wherever else to investigate some of the real foods at their eating and see how much carbohydrates they're consuming, what should they set for themselves as their upper daily limit of carbohydrates if they want to take advantages of being in this ketogenic state?

Dr. Attia:  Yes, so ketosis is a purely binary state.  It is you are either in ketosis or you are not.  Unlike carbohydrate reduction, it's a dramatic sliding scale.  So, if the question is you're specifically in ketosis, then as a general rule, I have not seen individuals who can routinely ingest more than about 40, maybe 50 grams of carbohydrate in the day, and more than about 125 to 150 grams of protein in a day.  Now the caveat is, and I've learned this primarily experimenting on myself and a few friends who have let me experiment on them, and timing is huge, and quality of carbohydrate is huge.  So, the 40 grams of carbohydrate I get, none of it is coming in starch.  It's all lactose, and you could argue that even Lactose is not truly getting a carbohydrate because half of it gets converted to lactate right away, and that lactate, of course, has no insulin effect at all.

Ben:  Lactose from dairy products, like the cream that you mentioned?

Dr. Attia:  Exactly, from my cheeses, from my creams which would make up a reasonable amount of my caloric intake.  I'm getting carbohydrates in the vegetable that I consume, but again, I don't really eat even starchy vegetables 'cause in ketosis, I would be able to.  So, I can't eat a potato, for example, or even a yam, so it's the few tomatoes and cucumbers and the lettuce and stuff like that.  So, I'm not even eating the types of carbs that typically raise those levels, so it's hard for me to give an answer that question because it's so complicated it’s so multi-factorial.  Someone gave me a look, I've got to have a Snickers bar a day, and that Snickers bar is 50 grams.  That's Snickers bar is guaranteed to take you out of ketosis, because of the quality of the carbohydrate in it.  Similarly, if you, and I've done this experiment where I'll go 24 hours of eating nothing, and then in one meal, eat all of my day's protein and same thing.  I'll enter that meal at a very high ketone level from fasting for a day, and if I slam down one hundred grams of protein in one meal, I will, within an hour, be out of ketosis.  So, timing matters, and then there's another variable that just makes it that much more cumbersome for people, and that is the amount of activity you're doing.  Some activity raises your ketones levels because it's allowing your liver to gradually access fats to break ketones, and some actually suppresses it, and I write about this in that exercise ketosis interplay where is that I tend to see that the higher intensity exercise tends to lower my ketone levels whereas lower intensity, those long bike rides, for example, they really raise my ketones.

Ben:  Is that because the higher intensity exercises cause your liver to release more storage sugar?

Dr. Attia:  I believe that is the case, Ben.  I think we would have to do some real, more than end of one experiments, but my belief is that it's probably the hepatic glucose output that's resulting from a catecholamines surge.  So, when I'm doing a set of Tabata or deadlifts to failure or tire flips, I mean that is just so glycolytic at the top, and that my liver is going nuts to get all the glucose out there, and I literally have done pre and post blood glucose checks separated by 10 minutes around exercises like that, and I can see my blood glucose rise by 30 or 40 points, which just precipitously drives my insulin up and then my ketones way down.

Ben:  Okay, got it.  So most cases, 30to 40 grams-ish of carbohydrates, a hundred to a hundred and fifty grams-ish of protein?

Dr. Attia:  Yup.

Ben:  And everything else is fat?

Dr. Attia:  That's right.

Ben:  Okay, now was this style of eating an easy transition for you, or in other words can we put specs to feel different, worse, better if they continue to exercising, how they're exercising right now, but just make that calorie recommendation that we just put out there in terms of total carbohydrate and total protein consumption?  What's the body going to feel like?

Dr. Attia:  I wouldn't say it's easy, and I think I'd be misleading people if I suggested this was an easy way to eat.  It's not difficult from a palatability standpoint, it's difficult from an infrastructure standpoint.  Food doesn't exist in the United States in a manner that's consistent with 90% of your calories to come from fat, and we live in a society that goes out of its way to do the opposite, right?  We're like the fat phobia, everything is low fat this, low fat that.  So, it's really difficult to do, there's nothing you can buy.  If it's a ketogenic diet you can wrap up in a package, literally cream cheese is one of the few things that actually already comes in that.  Same with butter, that kind of stuff, but these are high fat dairy products.  They're one of the few things that “come out of the box” in the right mixture, so most of it is me manipulating things, making a lot of really high fat salad dressings to put on my salads, really being mindful of how I eat protein.  I mentioned earlier when I make eggs, for example, I strip out some of the whites to get rid of some of that protein, just so that I can focus on the high fat and the yolk.

Ben:  Gotcha, so a lot of folks complain.  I know when they start to reduce carbohydrates that they feel kind of blah, slow initially, almost like they're bonking, did you go through that same kind of period when you started?

Dr. Attia:  I did, I absolutely did.  My workouts really, really suffered.  I think part of the problem is, and again, not to pick on everyone who says that or feels that way, but I think people forget that like I'm 39 years old.  So, if I spent 37 years of my life, training my metabolism to do a certain thing which is to preferentially oxidize glycogen, and to store fat, 'cause that's a typical North American diet.  It puts your body into that state.  If any, is it reasonable to assume that in one week of changing that, my body is going to adapt?  It's crazy to think that, right?  It's like imagine you drank five cups of coffee every day for your life, and then for a week, we didn't let you drink coffee.  I mean is it safe to say that you should say well clearly caffeine withdrawal is a bad thing because I feel like crap.  I mean I actually had a very interesting comment on my blog about this, where someone said imagine you take a heroin addict out of heroin, and he says he does all the time, and Baltimore was a heroin capital the United States actually.  So, I watched many people go through heroin as well, totally miserable.  I mean, people don't even know what misery is thinking about carbohydrate withdrawal until you see someone go through heroin withdrawal.  That doesn't mean that it's a bad thing because it's difficult to transition through them.  Now, it just speaks to the nature of the physiologic addiction you had to that agent before you tried to withdraw from it.

Ben:  Gotcha, but how long did that transition take you?

Dr. Attia:  Well, it took me I would say probably about four to six weeks, but boy is it variable.  I mean I've got people that write in and say this was easy peasy.  Two days later, I feel perfect, and I've got others that suffered like I did.  So, in retrospect, I would say that I probably should have tried to tone down my exercise a little bit during that transition period because I really only felt bad during exercise.  I mean I didn't feel that bad outside of the time I was exercising, but at 24 hours a week or whatever that I was putting into my workouts, they were really, really, just really difficult.

Ben:  Gotcha, alright.  So, in terms of moving forward as far as if someone transitions into the style of eating and decides that they're going to go out and they're going to exercise longer, going to exercise hard, have you found that there's any type of ceiling, and what I mean by that is we have people who are maybe listening in who are planning on doing an Ironman triathlon  on out there, possibly for an eight-hour training session or a fourteen-hour type of race day.  Have you spoken with anybody who's done things like that while in a carbohydrate-restricted phase, possibly even doing a very, very long training session like that or doing a race where they literally are doing something along the lines of 50 to 100 calories of carbohydrate, maximum per hour or so, and then just everything else fat?

Dr. Attia:  Yeah, it's not difficult at all actually.  The real nuance here comes down to what sort of activity are you doing, so let's take two examples.  Your goal is to perform well in Stage 16 of the Tour de France which includes a climb up Alpe d'Huez at the end, so it's a two hundred-mile stage that finishes with a quantum of Alpe d'Huez, versus Ironman Kona, right?  You're going to do the Ironman in Hawaii.  Now at the surface, you might say those are very similar activities, right?  Because, technically, the Ironman takes a little bit longer, but just to make the argument easy, there are roughly the same metabolic challenge, right?

Ben:  Right.

Dr. Attia:  But they're actually not.  The guy doing the triathlon has a huge advantage over the guy doing that bike race, and the difference is this.  In the cycling race, and anyone who rides a bike will know this, you as the individual don't have that much control over the pace.  If you're in a pack and that pack surges, you're surging.  If there is a sprint to break away or something goes on, you have to be able to really ratchet it up.  Triathlon, for most people, I'm not talking about the guys that are necessarily going to win that race, but for most people when you're doing the Ironman, you're doing it at your pace.  You're going to enter well-trained, what that pace is, but you're going to enter the race and say look, I'm going to do this when an hour five, and I don't care if others are going to be an hour two.  That extra three minutes is going to cost me too much pain, and that transitions as much as how I'm going to get out there on the bike, and I'm going to ride 18 to 19 miles an hour, with or without others, and let's not talk about the draft legal triathlon for a moment, and then I'm going to do this next transition, and I'm going to run my marathon in three hours and 45 minutes because that's the pace I run a marathon after I bike 112 miles.  So, these people have much more control over the tempo that they ride.  In fact, the guy who did my VO2 Max testing follow what he did my pre and post VO2 Max test on the twelve-week experiment.  I said wow, I mean your VO2 numbers now post-ketosis are a triathlete's dream, because now, I mean my RQ.  I don't hit an RQ of 0.85 until I'm at about 92% of maximum heart rate.

Ben:  So, you're burning a high amount of fat?

Dr. Attia:  Even at high intensity, so as I approach anaerobic threshold I'm still at 60% burning fat.  So, if you think about it, you're not at threshold for a twelve-hour Ironman, you are well below threshold.  So, if my threshold is 160 beats per minute or probably about 157 beats per minute, I'm going to be out about 144 to 146 beats per minute for 12 hours, and at a 144, 146 beats per minute, I'm 90% dependent on fat, only 10% dependent on glycogen.  So, in many ways, I think the athletes that have the most to gain by doing this are the people who are actually doing the longest controlled activity, and there's no athlete that fits that more than the triathlete.  The athletes, I work with a number of athletes.  The athletes I would never put into ketosis are the people who need the short bursts.  So, a road racer and cyclist, I would never put into ketosis.  A pool swimmer, so unlike an ocean swimmer who's doing long marathon stuff like I do, I wouldn't put someone who's trying to win NCTA Championships on a ketotic diet because it just doesn't make sense.  We need to optimize more for performance, even if it means consuming more carbohydrates.

Ben:  Right, makes sense.  So, in a way for something like Ironman triathlon, it depends how close you are to the point end of the race and if you are involved in a lot of the surges and other people dictating the pace versus if you're out there, racing 11, 12, 14 hours, that type of thing.

Dr. Attia:  Yeah, I need them still as you pointed out earlier.  I mean, a really nice adjunct is the use of Super Starch, and I think that the generation you can't keep a starch product is a remarkable bridge.  I have found that it does not have a deleterious effect on my ketosis.  So, I can actually consume lots of Super Starch in a day, and it doesn't seem to impact my ketones, and so that actually is a nice thing.  If someone's contemplating the foray into ketosis, but they're really afraid of losing any of that glycolytic power, I'd suggest doing an experiment where they try using the Super Starch in addition to a ketogenic diet.

Ben:  Yeah, I'm actually experimenting with a little bit myself right now as well.  Main issue that I found is that for the highly, highly competitive folks out there who are even doing something like being at threshold from the get-go, from the time a swim gun goes off in the triathlon to being at multiple 20 plus surges up to VO2 Max, climbing and passing and sprinting.  Those are the cases where it seems like a little bit more carbohydrate comes in handy, but for my training sessions, for example, I've found that this is working out fairly well.  Now what about re-feeding?  Carbohydrate-refeeding periods, specific days of the week, periods of the exercise year or even certain seasons like summer versus winter?  Do you change things up at all?  Eat more fruit or more carbohydrates than usual during any particular times?

Dr. Attia:  It's a great question, and then I'm actually contemplating doing that experiment this summer.  So, I'm contemplating leaving ketosis, probably June to September, and doing a low-carb, non-ketotic diet.  So, again, ketosis is binary.  You don't get to play around here.  If you're in ketosis, you’re in ketosis and there's no screwing around.  You don't get to refeed on carbs, you don't get to do anything like that, you're still there.  But the question is what if I give up some of the advantages of ketosis, both from the standpoint of my health, from a standpoint of my mental acuity and my energy levels, but that's probably the single greatest benefit to ketosis, frankly.  That's been the change in my profile of cardiac disease risk and my mental acuity and my energy levels, 'cause I don't have any subject fluctuations.  I'm not going to get fluctuations in blood glucose levels, but the question is would I give some of that up to have a little bit more athletic performance and add back in some carbohydrates, and the answer is yeah, I might do that experiment this summer.

Ben:  Gotcha, okay cool, and then one other thing that I wanted to run by, you mentioned the sodium issue and how you found that when you switched to a lower carbohydrate diet that you didn't increase your sodium levels because your kidneys were tending to excrete more sodium.  Did you find anything else, in terms of particular dietary supplements or strategies that helped you or that you think would help other active individuals who are exercising a lot and trying to eat few carbohydrates, succeed with or adhere to a low carbohydrate diet?

Dr. Attia:  I think it really comes down to three things.  One is electrolytes, the other is sufficient fat and the third is significant or sufficient hydration.  So, on the electrolyte’s thing, in order it's really solved magnesium and potassium, and for most people, just getting the salt and magnesium fixed is enough that you don't need to supplement potassium.  For me, that salt is a pretty large amount.  I'm concerned, I supplement two to four grams a day of salt, in addition to what I'm getting in food, so I'm eating about six grams of sodium chloride a day which is about four times the “recommended amount” by the American Heart Association which, I'll try not to say anything too disparaging about them.  So, salt is huge, when you fix the salt, a lot of other things get fixed, why?  Because the body will do everything in its power to conserve sodium, even things that seem counterintuitive and harmful, to give you an example.  When your sodium level starts to get low, your body starts to produce a hormone called aldosterone.  Aldosterone says to the kidney save me the sodium, pull the sodium back in, but you have to do it at an exchange of one to one with something that has the same charge of sodium which is potassium.  So, it turns out that probably the biggest cause of hypoglycemia with low potassium is actually low sodium 'cause your body's doing everything to hold on to that sodium unless you get rid of the potassium.  So, when you fix the sodium and you fix the magnesium as well, you tend to fix the potassium, but if not, those are the three things I'd like to supplement.

Next thing is on the oil side.  I find a lot of people, who want to do a low-carb diet aren't comfortable eating fats yet, and the problem with that is if you're not comfortable eating fats, you're stuck overeating proteins, and so you get into this vicious cycle where you're not getting the great energy source, you're eating too much protein, you really start having that lays that's associated with high levels of protein, and your energy levels go down.  So, I like to kickstart the day with a little bit of MCT oil as I mentioned, but even throughout the day, oils play a big part in what I do.  And the only thing I'm really avoiding is the Omega-6 oil, so I don't eat oils that come from canola safflower, sunflower, those sorts of things, so it's a lot of olive oil and coconut products as well, and the third thing is hydration.  A lot of people just seem to forget that the body needs a lot of water, and I think that's true regardless of whether you're in ketosis or not, but I find that a lot of people just aren't paying attention to their hydration status.

Ben:  Gotcha, okay cool.  We have gone for almost an hour now, and this is actually longer than I interview most folks, so I know we're kind of pushing the limits here, but if you have time, can I throw a quick question about thyroid at you?

Dr. Attia:  Sure.

Ben:  I've seen some discussion about low carbohydrate intake affecting thyroid function or thyroid production and also potentially affecting leptin sensitivity.  Are either of those concerns for you, or do you think that those are blown out of proportion, or do you think it's something that should be discussed when it comes to implementing a low-carbohydrate diet?

Dr. Attia:  Well, it's funny.  So, the data are confused on this, then there's two issues to figure out.  One is the issue of if it’s clinically relevant?  In other words, do you observe a laboratory trend, and two, is it clinically significant?  And the data are all over the place, to be clear.  So, there are some people out there who have data that show that free T4 levels, T3 levels go down.  RT3 levels go up, TSH levels go down, all these things.  I've never seen data suggesting that this is clinically significant, meaning that the reduction in these things results in a clinical change in an objective sample of the population, and I've seen as many, if not more data suggesting that it's not an issue at all.  So, I'm left to conclude that if there is an issue there, it's probably not that significant.  I do question whether part of it has to do with failing to get enough sodium in.  In other words, is it possible that people who are failing to get enough sodium are potentially running into thyroid problems?  That's a hypothesis, that's nothing to test that.  The other question I have is what are the baseline status of these people, so an interesting experiment I'd like to see done would be to take a group of patients who are already hypothyroid versus a group of patients that are euthyroid, have a normal thyroid, versus a patient a group of patients that are hyperthyroid, and again, all three of these types of people exist in the world, and actually do a real experiment, right?  Which is reduce the carbohydrate significantly in all of them, control for every other variable, and let's measure what's happening.

So, a long-winded answer to the fact that says I haven't seen any evidence that has convinced me this is a real problem, though I've heard no shortage of rumbling about it, and I've read more papers on this than I can count, and they just don't seem to convince me.  So, I guess it's probably still a little bit of a gray area, and it's certainly worth testing, but if you look at the physicians who are treating hundreds of patients, thousands of patients with low carbohydrate diets, and I've spoken with many of them, they're just not talking about this problem, and I asked them point blank and they said we're not seeing it.  I mean we're checking thyroid functions on everyone, and we're not seeing it, but yet it does show up in semantic total reports.  So, I'm not really sure what to make of it actually.

Ben:  Gotcha, I was just curious if you'd seen it much.  So, at this point, not a huge worry, probably especially for folks who are already very active, right?

Dr. Attia:  Yeah, I mean I would say the following.  If you have hypothyroidism, you've got to get that fixed.  I just don't know that the diet is the issue.  I think there's a lot of people that have hypothyroidism, so I would want to spend a lot of time making sure that people do in fact have their thyroid function check, but for me just to think that there's something systematic going on, I haven't seen any data to support it.  So, it isn't that hot.

Ben:  Gotcha, well we've certainly covered a ton of information, and if you're listening in right now, I will be sure to link to any resources that Dr. Attia and I discussed during this interview.  I know that you'll probably have questions, comments or feedback, so you can leave them over on the show notes for this episode at bengreenfieldfitness.com, and we'll continue to explore the nutrition issue and answer your questions.  So, Dr. Attia, thanks so much for the generous amount of time that you gave us today in explaining this.

Dr. Attia:  Well, Ben, it's been my pleasure, and hopefully folks found this not too confusing and hopefully more interesting than anything else.

Ben:  Sounds good, and remember if you're listening in, Peter's website is waroninsulin.com.  So, Peter, thanks and have a great day.

Dr. Attia:  Thank you.

In today's interview, I speak with a surgeon, engineer and relentless self-experimenter, Dr. Peter Attia (pictured above as he swims across the Catalina Channel), about whether it is possibly to be extremely active and eat a low carbohydrate diet.

If you've ever wondered whether it's possible to keep yourself in a “ketogenic”, low carbohydrate state and still swim, bike, run, lift and do other extreme sports and activities, then this audio will answer all your questions.

Let's begin with a video of a workout being done by Dr. Attia, who I interview in today's podcast:


And he does all that while eating only 30-50 grams of carbohydrates per day!

Dr. Attia (pictured right) of Canada is a relentless self-experimenter who has spent the last two years examining the role of nutrition on all aspects of personal performance. He is a former McKinsey & Company consultant, surgeon, engineer, calculus teacher and an author of numerous medical and research papers.

Dr. Attia received his medical degree from Stanford University and holds a B.Sc. in Mechanical Engineering and Applied Mathematics from Queen’s University in Kingston, Ontario, Canada, where he also taught and helped revamp the calculus curriculum. He did his surgical training at the Johns Hopkins Hospital in Baltimore, Maryland. He also did a fellowship in surgical oncology at the National Cancer Institute in Bethesda, Maryland.

Dr. Attia's website, which we discuss during the interview, is WarOnInsulin.com.

Here are the questions that I ask him:

You have an interesting story. How did you come to start your website, WarOnInsulin.com, and what is it that you are trying to achieve?

You appear to keep yourself very fit. Walk us through a typical week of exercise for you.

For any given day, especially on these exercise days, about how many carbohydrates do you eat, and what does your eating look like?

How about before and during a long workout, like a long bike ride. What do you eat?

What is the science behind how your body is able to accomplish so much exercise with so few carbohydrates?

What research is out there that has been conducted on people exercising very long, very hard or both while eating low or no carbohydrates, and what has been observed in the research?

Is there a “maximum” amount of carbohydrates that would be considered healthy for frequently exercising individuals, such as enough carbohydrate to keep liver glycogen stores full?

Was this style of eating an easy transition for you, and how can people expect to feel if they try to combine high volume or high intensity exercise with carbohydrate restriction?

Have you found a “ceiling” for how long or how hard you can go while in a carbohydrate restricted phase?

Do you feel or have you observed a need to include carbohydrate re-feeding periods, whether specific days of the week, periods of the exercise year, or seasons in which you may eat more fruit or more carbohydrates than usual?

Have you found that particular dietary supplements or strategies help active individuals to succeed with or adhere to a low carbohydrate diet?

Some studies have shown low insulin and a low carb diet to reduce thyroid function or cause leptin resistance. Is that true, and if so, is it an issue?

Recommended reading as an additional resource:

Art & Science of Low Carbohydrate Living

Low Carbohydrate Diet For Triathletes

Recommended supplements for long workouts:

UCAN Superstarch – use plain flavor only (avoids the sucralose), 80-100 calories per hour

MCT Oil – use 30-50ml 30-60 minutes prior to workout

Other resources:

Blood glucose monitoring system

Ketone strips






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