Low Versus High Carb Diets | Dr Christopher Gardner | The Proof Podcast Bonus EP

maybe what's going on here is there are certain people who should be on certain diets and so that sort of generated the hypothesis that's what i should be looking for not for the best diet i should be trying to look for things that would predict if you were predisposed to do better on one diet or another welcome to the proof podcast a space for science-based conversation exploring the health and longevity benefits that come with mastering nutrition physical exercise mindfulness recovery sleep and alignment facts nuance and trustworthy recommendations minus the hyperbole hey friends i'm your host simon hill i'm a qualified physiotherapist and nutritionist with an undergraduate science degree and a master's in the science of human nutrition today i sit down with professor christopher gardner from stanford university among the nutrition science field dr gardner is considered to be right at the top with respect to expertise dedication and science communication if you spend just a few hours scrolling through his various lectures on youtube you'll quickly see why he's so highly regarded dr gardner has nearly three decades experience as a scientist studying nutrition publishing over 140 papers in leading scientific journals such as cell jama and nature medicine he is perhaps most well known for performing robust randomized controlled trials involving very high quality dietary interventions two of these being the ada zed and diet fit studies comparing low to high carb diets we can find anecdotes to support almost anything what i think is more interesting is where does the science lie when high quality research is performed do we see an advantage to adopting a low carb or high carb diet when it comes to losing weight that is the topic of this bonus episode which is a throwback to episode 145 of the podcast with the video from that episode being made available for the very first time please do enjoy this is me and dr christopher gardner dr christopher gardner welcome to the show thanks for having me simon it's uh it's been a long time coming uh you know you know you're a rock star in the in the nutrition science world right i don't know i've been having a little bit of fun on twitter lately but the carnivores definitely don't like me well if we get some time we'll we'll go into that i think people would find that interesting uh i know certainly from from my perspective i think your approach to science and communicating the science is really second to none so thank you so much i've closely followed your work and and i've learned a lot through it i really have oh thanks and in fact just to kick things off here a little little secret i haven't actually shared this with anyone i think it's quite funny some of my friends might might be listening and i i love uh a good movie or documentary or something to unwind at the end of the day netflix whatever it may be and and i've got a bit of a reputation people friends will message me and say well what's the latest what should i watch and i've developed this new strategy where i'll send them one of your your lectures one of your stanford talks on on youtube and i tell them to to watch that come back to me with one key takeaway and then i'll give you the name of a great movie to watch and and it seems to be working it seems to be working wow okay uh so it's definitely it's definitely uh hitting home with a few of my friends that's for sure those lectures are brilliant hey so let's let's set the scene here for for the listeners before we sort of dive into some of the really cool stuff we're going to talk about with regards to your studies how did this career in nutrition science sort of come about for you am i right that it goes all the way back to you working at a cafe it actually really goes back to my philosophy degree undergrad upstate new york thought why the hell am i in college i should never have been in college i need to be a bohemian and find out what's going on in life and so i lived in a bunch of places and working in restaurants is the easiest way to do that and along the way there was a girl and she dumped me and she was a vegetarian and i thought well maybe if i switch to a vegetarian she'll take me back she didn't take me back i liked being a vegetarian six years went by after college and i thought damn i really should do something with life wow i've worked in a lot of restaurants maybe i should have a vegetarian restaurant and so i actually started thinking along those lines and i thought somebody's going to make fun of my amino acids being a vegetarian so i'm going to go to berkeley which is where i was at the time and i said can i get into the master's program here and they said dude you never took any science in college all you took were philosophy classes i said yeah it's just food they said oh no no you need regular chem biochem organic chem physiology biology i said i'm not afraid i'm not afraid i'm an older student now i'll take all those classes and i took for two years i just took makeup classes and i actually got all a's and a pluses being an older student at this time simon and so i went back with my birkenstocks and my long hair and i said i'm back i took all those classes you didn't think i'd take and they said yeah you're right we didn't think you'd take them but look you're smarter than we thought when you were in the philosophy program you didn't get very good grades but look at you as a scientist why don't you get a phd and i thought why the hell do i need a phd to open a vegetarian restaurant but oh oh and i remember how great it is to be full of potential in college people say what are you going to be when i grow up i don't know i can be anything i'm still in school and i wanted that feeling again so signed up for the phd finished it at that point totally confused as to what i wanted to do i i started thinking i'd be a teacher but i didn't get a job and at the last minute with a wife and a kid in tow i got a job as a postdoctoral research fellow at stanford university in 1993 and simon in my phd program i found in my program and in others in other universities so much of nutrition was mechanism rats cells and and not behavior and i had actually been really interested in culture and behavior and this group that i started the postdoc with was all about behavior so it's in a department of medicine there are a lot of behavioral psychologists and so half behavioral psychologists and then half content experts so i was a nutrition expert there was a physical activity expert tobacco control expert but it was really about how do you get people to change some of their habits and i thought ah this science i really like more than the rats and the cells and the mechanisms i really want to see if i can get people to change what they're eating and stick with it so that's a little background of how i got here was really a whole bunch of mistakes to be perfectly honest and so i think you you i guess in nutrition science are very well known for lots of studies but two in particular the a to z and diet fits of course how how did things sort of go from that earlier stage of your career to then becoming interested in this whole low-carb versus low-fat kind of conversation and and also why why the interest in in weight loss out of all things that you could have gone and and studied what gave you that spark to want to know the effect of different diets on weight well so to be honest it definitely didn't start that way so being a vegetarian i was really into the different things that were in plant foods and so there's a name in my field phytochemicals phyto just means plants so chemicals that are in plants and that's usually typically not a vitamin or mineral sort of something that doesn't have a recommended daily allowance but might be a cool thing to eat or avoid so i actually had a dream that my license plate was going to be dr phyto i was going to be doctor phytochemical and i got nih funding to study garlic and the allicin in it and soy and the phytoestrogen in it and ginkgo biloba i had all these big nih grants and i would go and present these at meetings simon i'd finished an hour-long talk and i'd say you might have been confused you know if you really want me to go into the mechanism of the putative active agent allison and garlic i'd be happy to expand yes you in the front row what would you like to ask and they said do you think you can lose more weight on atkins or zone and i said jesus for the last hour i talked about this thing that i did and it happened repeatedly and so what i got the sense of was that this was a topic that a lot of people were interested in frustrated by there wasn't a lot of evidence in it and so i actually wrote up a little pilot study at the time and that turned into one iteration after another after another and to be honest the a to z study initially was supposed to be a um a pilot study i wrote to the nih for a big grant and they said you just do phytochemical stuff you're not a weight loss person we're not going to give you that much money and they gave me some starter money and then there was a very interesting court case against a weight loss drug that had gone wrong against them and the the money that was awarded to the court case had to go to university investigators i got a million and a half dollars from a court case that got added to the nih funds that was the a to z study that ended up being the most money i had ever received just because i sort of had something in hand when the stanford folks came by and said you know there's this huge pool of money if anybody has anything ready right now it has to be about weight loss you might get this so a to z again it's another mistake in my life simon but great timing uh in in the a to z z study actually let's go through what that study looked at i know you looked at four different diets i'm interested in in sort of how you chose those four diets was that because they were the best-selling books uh and and sort of what the the methodology was of that study and and really what you learned from it that would later sort of inspire the the next little research that you did yep so in my field one of the hardest things is defining a diet and getting adherence to the diet and showing that you've got adherence to the diet and this is very problematic when people say they've got a diet and they've got a certain percentage of carbs or fats in mind and they assign people to it and this isn't for one meal this is for months or years and so it's really hard to do that kind of thing so when i when i wanted to test this i thought you know how is the general public doing this they're going out and buying books so if i just go assign some popular books then i'll really be answering a very generalizable question do these books help people do it so some people gave me a hard time saying you know why are you doing that why isn't it a specific proportion of fats and carbs i said but that's not how the public's doing it they're going out of buying atkins and zone and ornish and that's a huge spectrum that would make for a great comparison and then when people say so you know how do you know they were adherent i said well to be honest we got a dietitian and we had a lot of money and we got 300 women and she basically read the book out loud to them once a week for eight weeks she read like an eighth of the book okay i'm being a little ridiculous she didn't really read it out loud but she made sure every one of them knew that the book that they got assigned had been thoroughly understood and then very intentionally we decided it was a one year study so after the eight weeks of getting this help from the dietitian and going through the book we told them up front we're not gonna help you anymore we want this to be a generalizable study and once you've understood the whole book it's up to you to follow it the best you can for a year because that's how the american public is doing it they're not even getting a dietitian to help them for eight weeks and so let's just see how the cards fall when we do it that way so it was very intentional to do it that way and should i jump to the punch line and what happens yeah i think on that though that point there is a key learning i think the generalizability is something that is often overlooked when when particularly on twitter you mentioned before when critiquing a study you know we you can get people into a metabolic ward and lock them in and they're really interesting studies but that's that's people being fed it's not really giving insight into adherence and their behavior and what happens in the real world so that's what i love about this study is that you were very much just taking a really good look at if if people get these books how successful are they um without being forced into into eating that way um okay cool so come to the punch line what happened yeah well let me just build on what you said just for a moment so i feel like in my field metabolic ward chamber for any of the listeners that aren't familiar with this there's a guy kevin hall that i really love who does great studies and he usually doesn't do any more than 20 people at a time because they're incarcerated he uses the word domiciled i think it's incarcerated he incarcerates these people in a building there's bars on the windows and they can't leave and there's a chamber that they have to go into and he can do a lot of very rigorous stuff that's not very generalizable and then i do stuff that's very generalizable it's not nearly as rigorous as him but what i really like about kevin's studies is he makes them as generalizable as possible for a rigorous controlled domiciled study and i really try to make my generalizable studies as rigorous as possible i really try to apply all the tools in science we have to define the diets well and get adherence the best we can and be taking blood samples and other factors and surveys to see who's more and less adherent so in my as maximally rigorous as i could generalizable study we got 300 women to be in this study for a year and there was almost no average difference between them at the end if there was there's a little advantage for the group that did atkins they actually sort of lost more weight at the six month mark if you look at a graphic of what happened the weight was actually coming back on faster for them for the other group so by 12 months the only actual statistically significant difference was between atkins and zone which is weird those were the two low carb diets if there was really a low carb low fat thing it should have been between ornish which was the lowest fat and atkins which was the lowest carb and those actually weren't different and we had a fourth diet that was more of a health professional's approach it was called the learn manual by kelly brownell it's really what a healthcare professional would probably use and it was in between learn and zone in terms of fat and carbs so on the one hand it was it was a little disappointing that there wasn't a clear winner on the other hand uh it gave me a very practical public health message there isn't any one diet that seems to work for everybody and so there isn't one thing that you should all try the the mind-blowing thing for me was i had a colleague at the time simon who was always pushing me to present my data in different ways and one of them is what i call a waterfall plot and instead of the typical thing which is you show a bar of the average change and some magnitude of variability with what we call error bars so once you just plot every damn woman on the graph make every woman a bar and show how much weight she lost or gain because a small proportion of them gained weight and so what i saw from this first study was that if you looked at the pattern of weight change which on average was only a couple kilos different for each group on every group somebody lost 25 or 30 kilos somebody gained 5 or 10 kilos and those weren't outliers it was an absolute continuum from one end to the other and so i just oh my god maybe what's going on here is there are certain people who should be on certain diets and so that sort of generated the hypothesis that's what i should be looking for not for the best diet i should be trying to look for things that would predict if you were predisposed to do better on one diet or another that was my big takeaway from a to z before we we kind of move on to to i guess what you then went on to look at in in terms of trying to decipher uh how can we predict who will be successful on on what diet or low carb or low fat uh all science part of sciences is being open to critique and being open to to challenge and am i right that dean ornish was a little he was a little mad and i guess this goes back to speaking about what we were before around adherence he was a little a little mad with the way that the ornish diet was adopted he was yeah he said hey if you look they never got to ten percent fat that's my diet and i said i know dude but not only did i buy the book for them i gave them a dietitian to read it aloud to them so great if your book works for the people who can follow it i found the general public can't really follow it so simon i got an even funnier comment from barry sears who did the zone diet and that was if you look at the people who got assigned to zone which is a 30 30 40 where it's 40 carb 30 protein and 13 30 fat they didn't um they didn't really follow that very well when they were assigned to the zone diet but the folks who followed atkins also didn't follow it very well they fell short of going low as low in carb as atkins said but the people assigned to atkins actually came out looking kind of like the zone and so barry sears had this bizarre torturous interpretation he said see my diet's best the group that lost the most weight in absolute numbers was the atkins group and i said yeah that was the acting yeah but they were eating pretty close to what i said they should eat and so i said okay really so to follow your diet they should choose someone else's diet oh the poor public this is crazy okay yeah so so the biggest takeaway being that there didn't seem to be too much difference between these different four diets but within each diet there were some people that did great and there were some people that didn't do as well you're left thinking well what on earth explains this what can what can predict success or lack of success so you go away no doubt you're sort of scratching your head lots of meetings with colleagues and and over a period of years you you put together the diet fit study can you can you walk me through this period and and what your hypothesis was and what led you to to dig a little deeper into this yeah sure so pretty much right after we published those main findings i was continuing to look into this field and the first two or three studies that i saw that were the most relevant were some of these smaller controlled feeding studies small numbers short amounts of time and they were looking at this concept of insulin resistance and insulin sensitivity and the idea for your listeners here is this is you can have two people that look very similar they both have similar amounts of excess adipose tissue you know physically they look the same metabolically they were different if you looked at their glucose insulin some of their blood chemistries you saw that some of them were actually pretty metabolically healthy at an at being even though they were overweight and some even though they weren't all that overweight were metabolically unhealthy and one of the common themes that was coming up at the time which is quite popular now but it was kind of new at that time was this idea of insulin resistance which meant that on a standard low-fat diet which was the existing paradigm for decades before the millennium turned over there a low-fat diet is the high carb diet and people who are insulin resistant the idea here is you have consumed some carbs your blood glucose goes up your pancreas senses this it produces a bunch of insulin which is designed to get the glucose out of your blood and put it away and people who are insulin resistant the glucose doesn't actually get put away as efficiently as it should be and the pancreas senses that and says huh guess i didn't make enough insulin i'll make some more and some more and some more and so we have a huge population in the u.s anyway of people who have pre-diabetes they actually their glucose level doesn't qualify for them for being in the diabetic range but if you were to measure their insulin which i don't know if you know this it's not a standard clinical measure glucose is cholesterol is insulin i think it will be someday soon but it's not a standard clinical measure if you look at that for those people it is sky high and so really what's happening in those people who are not yet diabetic is they are borderline diabetic because their pancreas is working its tail off to make enough insulin to get that glucose put away and their bodies are flooded with extra insulin which does different things about how much fat you're storing and how much you're releasing and which anyway it's not good it's metabolically unhealthy and that was my first clue to see these three papers that said hey if you split people into who is the most insulin sensitive which is healthy and insulin resistance which is metabolically unhealthy wow those insulin resistant people really shouldn't be on a standard low fat diet because it's high carb they have a hard time putting carb away and so i thought ah that is a brilliant insight i wonder if that's one of the things that could have predicted this variability within the diets let's go back and look at our old paper from a to z our old data and we had a very crude measure we only had fasting insulin which is not a very good measure just what they've taken in the morning after an overnight fast and we did a little paper and when we picked atkins and ornish as the low-carb and the low-fat groups and we looked at who had higher and lower fasting insulin in the morning it was significantly different and the ones who were the most insulin resistant who got assigned to ornish had had the worst time following it they reported not being very adherent and this is funny to me because we didn't tell them what their fasting insulin was everybody just got assigned or a quarter of the women just got assigned to the ornish diet and i said ah they didn't even know this and somehow metabolically something's making it hard for them to follow it and maybe that's why they're not losing weight okay so i'm going to try to do a new study and there's better ways to do it there's something called an oral glucose tolerance test so you have to come in in the morning you're fasted again haven't eaten anything for 12 hours and you have to drink this glop you have to drink 75 grams of glucose in a lemon or orange flavored thing that's really disgusting because it's solid glucose now i don't know if glucose sounds sugary to your listeners but things that are sweet have sucrose in them that's half glucose and half fructose and it's the fructose that's sweeter than the glucose if you have to drink i don't know if any of you any of your listeners have um tried corn syrup so try dipping your finger in corn syrup if you're ever baking it and it is like cloyingly disgustingly sweet and on an empty stomach it flies into your bloodstream and so what you do in this test is you give them 75 grams of glucose and you measure their blood insulin and glucose just before you give them the drink and then at 30 60 and 120 minutes later and when we did that with a practice group of 60 people we saw a 40-fold range of difference in how much insulin they made to that same 75 grams of glucose and they were all roughly in the body mass index index range of 28 to 40. so they were all overweight or obese but no one was morbidly obese no one was thin so they looked kind of comparable oh my gosh massive changes in this insulin resistance idea so that was the fun thing that i wanted to follow up on and simon i wrote that grant three or four times and none of them got funded this is maybe a fun insider part of the story here the reviewers kept writing back kept saying ah you're measuring this insulin resistance thing the wrong way and i kept turning the pages waiting for them to say the right way to measure it is and they never did bastards they like told me i was doing it wrong and then they they didn't offer me the right way to do it and really what i come to understand is there's a whole lot of ways to measure insulin resistance and sensitivity and the best ones are prohibitive there's a famous guy at stanford that died recently jerry reevan he used to hook people up with an iv in both arms for eight hours to figure it out dad you cannot do that to the average person and so i just kept biting the bullet and saying okay look there isn't a perfect measure of insulin resistance and sensitivity it's a continuum from one end to the other this is how we're going to measure and they didn't they didn't fund it i rewrote it they didn't fund it just about this time simon somebody else just came out of left field and said wow we think we have a key to this whole thing we think people are genetically predisposed so there's this other side of life with something called single nucleotide polymorphisms snips for short they're just single amino acid type or single base pair substitutions in your dna and they can change the function of for example an enzyme that might metabolize carbohydrate or fat and they had looked through all this growing field of snips and said we have identified three that we think are involved in carbohydrate fat metabolism have at least one paper published on them and mechanistically would make sense that we could predict which direction it's going to go could we go back to your a to z data and could we see if this would predict differential weight loss i said ah i never collected any dna but we wrote to all the women and we got of the 300 we had about 140 respond we sent them a cheek swab kit they got their dna by doing the cheek swabs so we kind of retroactively went back and not all the data works only 120 of it was clean and of the sort of the uh they're called genotype patterns so a low-fat genotype pattern was about 40 of the population a low-carb genotype pattern was 40 and 20 were neither there's 20 that it didn't really seem to go one way or the other so i went from 140 to 120 and of the 120 20 didn't count and then i've got four diets and so the numbers start getting really small here as i'm starting to look at who i have data for but in this very small set of data it was fascinating it totally looked like it worked so i went to the american heart association meeting i presented these data i resubmitted my grant and i said not just insulin resistance we're going to look at two things at once we're going to look at that and genotype pattern predisposition and boom i finally got funded after multiple rejections there goes the the genotype that got you over the line just to just to clarify on in case some of the listeners are hearing that for the first time what your predicting or we're predicting here is that some individuals may have a genetic predisposition to doing better on low fat and then some with a different genetic predisposition could do better on low carb and you were wanting to then run another study with more people more dna samples more genetic information to determine if that was the case to answer that question and to do the right insulin resistance test that would be more sensitive than the one i did before and so this time got funding for 600 people double the other size of the study this time men and women and we actually had that what's called statistical power to be testing really two things in one study the genotype pattern predisposition and the insulin resistance versus sensitivity predisposition hey friends i hope you're enjoying this episode so far a quick message from one of our sponsors who makes this show possible and then we'll jump straight back into things if you're familiar with my nutrition philosophy you will know that i'm a huge believer in plant-rich diets being better for people and our planet you'll also know that i frequently draw attention to what i describe as nutrients of focus these are nutrients that science shows plant-based eaters whether plant predominant or exclusive can fall short in which can leave you feeling run down lacking energy experiencing brain fog and generally just not as vital as you'd like to be for that reason together with a meal a plant-based health and wellness company i formulated essential 8. essential 8 is your one stop multi-nutrient formulated with dha epa omega-3s from algae oil vitamin b12 iodine vitamin d3 iron zinc selenium and calcium to perfectly complement your plant-rich diet i personally take essential aid every morning with breakfast just two capsules much easier than supplementing with these eight key nutrients individually what's even more convenient is i have a monthly subscription so it turns up automatically on my doorstep and i never miss a beat to get yours head to the proof.com forward slash friends that's theproof.com forward slash friends where you'll find a link to purchase essential 8 that will get you an extra 5 off your first order on top of the significant subscription discount there will also be a link to this in the show notes okay back to the show okay so this study like the a to z is a randomized controlled trial that's what you like to to do which is high quality high quality science uh 12 month trial again walk can you before we walk through the results can we go through a little about the methodology because i know that you paid particular attention to making sure that the diet quality was was emphasized and that was something that was really important to you can you explain why that was important and sort of how you went about ensuring subjects did understand what a high quality diet looked like yeah and let me start that up before the high quality let's talk about how low is low carbon how low is low fat i mean we were going with the assumption here that certain people wouldn't be able to get as low and keep their diet as low in carb or fat because they were predisposed it wouldn't be a will power issue it wouldn't be a test of personal integrity it would be some metabolic thing just saying okay look human body you are trying to avoid all this stuff and it is not working whereas somebody else it might be just easy am i oh my god this is i didn't realize how easy it was to cut all this out because we had heard that anecdotally many times before i bet many of your listeners know somebody's lost a lot of weight and somebody tried to do the exact same thing and it didn't work so we didn't want to penalize people for not hitting 20 fat or 20 carb so simon we actually tested this in a study that we published before diet fits and the study was really designed just to test an approach to doing this and i was pretty sure i would get pushback from my colleagues because it wasn't clean and clear it wasn't 20 of this and 30 percent of that and we have a really horrible name that i love and it's called limbo titrate quality and so the limbo titrate quality method was as they joined the study we said you have eight weeks you're either just gonna get not four diets this time just two low carb or low fat we want you whichever one you're on to get down to 20 grams of carbs or 20 grams of fat in the first eight weeks and people eat about 300 grams of carbs a day and they might eat 90 or 100 grams of fat a day and getting to 20 means you are excluding many of the things that you are accustomed to eating right that's hard work it's hard work and another thing that we were very interested in is doing something generalizable as you pointed out before we were hopeful that if one of if we found diets that worked for specific people but not others that when the study was over they would be able to continue that diet i didn't want a diet that would only work during the research portion so he said we want you to lower your carbs and fats carbs or fats to 20 grams a day for the first eight weeks and then once you get there and you don't all have to get there at the same time some of you type double a's will get there faster and some of you type b personality folks will get there slower why don't you try to stick there for a couple weeks and anchor yourself psychologically low and say yep i'm going to do this i'm really going to wipe out that many carbs and fats for my diet but honestly at that level you have to exclude so many foods to get that low on either end there's some nutrients that are hard to get um in a balance of nutrients so i said we actually don't think it's healthy to stay that low forever but we do want to psychologically anchor you that low and then we'd be willing to allow you to titrate back up so up until month three or month six go ahead and try adding another five grams a day in for a week or two how you doing are you still ah you're still feeling that this is punitive it doesn't work in your social life well then it's not going to work for real okay add another 5 or 10 grams back add another 5 or 10 grams back and this titrate concept was such that if you got high enough that it seems like you overdid it and the weight is coming back on and you're disappointed and you want to go back you could go back down again we weren't holding you to that higher level every week you were supposed to drip drip drip titrate this to a point that you thought you could maintain and then go back down again if you could and find that lowest possible level of carb or fat that you could do and look us in the eye and say yeah i think when the study's over if this thing works for me i'm going to keep doing this because i can do this socially i can find the foods it's practical culturally appropriate for me and then the third component which is one of my favorites was quality he said okay you can't game the system i've done this before i know some of you are going to go to the store and say oh i'm in this new stanford study and i found the brownies the potato chips and the candies that all say low fat or low carb on them so i'm gonna eat that no no no no no you're supposed to eat vegetables every day no matter which group you're in vegetables don't have that many calories sure they have lots of carbs but they don't actually have that many calories so even the low carb folks can have broccoli and cauliflower and lettuce and red bell peppers but we really want you to choose quality foods and we've got a dietitian assigned to you for the entire year actually we had five dietitians assigned to them and simon this is kind of fun from the point of study design and implementation we had five excellent dietitians and every one of them had to teach at the same time as we went through this study for several years a low carb and a low fat class they both taught both classes and we said and and i we want you to be proud of what you're teaching these people we don't want to feel we want you to feel like you've compromised yourself oh i have a favorite diet here and oh i'm sorry you got the shitty diet and so i feel really bad you got that one and i gotta tell no we wanted them to say if you're gonna do this we want to do this the best healthiest way possible and they a fun thing just to tell you from our staff meetings every week where they had predisposed ideas of what they thought was better and we blew their predisposed ideas away like they did have a favorite but they saw people on both types of diets thriving and both types of diets failing and they were doing their best so i think that's a good point diet fits itself would you say the the the primary rationale for the study wasn't to see if low carb was better than low fat but was more about seeing within each of those groups back to that what you said before the genotype and the insulin resistance do they explain success or lack of success exactly yeah so nowhere in the hypothesis was there that low carb or low fat would do better that wasn't and in fact sort of an expected thing was if we did them both as healthfully as possible they would come out almost even on average but what we were counting on was a huge range of variability and so actually as the study was going we could keep track of average weight loss and a lot of people lost a lot of weight and the average looked the same and if you are familiar with this we were blinded to the study results but that didn't unblind us that was never our hypothesis the hypothesis came when we revealed who was insulin resistant or sensitive and when we revealed who had a low carb or a low-fat genotype pattern so in this study was was the the variation in in weight loss within each group was it widespread like the a to z study and did was it explained by the the genotype and and uh insulin resistance so the variance was just as high as we had expected once again a bunch of people lost 25 and 30 kilos bunch of people gained 5 and 10 kilos everything in between huge drum roll the insulin resistance didn't work and the genotype pattern didn't work neither of them predicted the massive variability that we saw this is like 10 years of my life and i was like oh this hypothesis makes so much sense and it failed were you were you deflated or did that was that a success to you because it kind of ticks those off and then sets you on a new direction for looking at well hang on if it's not these these three snips and it's not insulin resistance then what is it is it behavior is it hunger drive like what what can explain why some people are doing well on on a particular diet and others are not yeah so it definitely was deflating for the first moment but throughout the study we were all super proud of what we were doing for how many people we retained in the study for how well they were trying to follow it the dietitians were all really proud of the participants themselves they could see how hard they were working at this we were really collecting lots of data to be able to explore different alternatives so i wasn't really actually all that keen on the genotype thing i know that pushed me over the line for getting funded but there's about a hundred different snips that are related to weight and we only had three in a very specific pattern so they were really we didn't test we didn't test genotype we tested these two specific genotype patterns there are hundreds of other potential patterns that could be looked at so i thought that was a far cry but i had really been convinced by this metabolic data about the insulin resistance and sensitivity thing of which people were writing yes but they're small and short studies somebody should do a larger longer study i thought this is great i'll be able to nail this one because it's long enough and large enough and i have all the measures i need this time nobody's going to question us so when it didn't work yes i was deflated for a moment but then i thought you know one of the things that we are super proud of was that we focused on this high quality aspect so we didn't set one up to be the straw man to be knocked over maybe if you're choosing a high quality low carbon high quality low fat whether you're insulin resistant or sensitive or not doesn't matter and that actually you know from another angle can be helpful to people oh my god i found out i'm insulin resistant except i hate eating this but apparently i'm supposed to no actually if you choose a high quality diet then you could lose weight on both of them and so that was actually the practical message that i came away with i got a couple other hypotheses but sort of the public health-facing message was we did this other people have reported it's different we because our results are are larger and longer than some of the other ones we we're not inclined to say oh they were right and we're wrong we did it wrong we're inclined to say maybe some of the other diets weren't done with enough attention to quality so maybe and this is true in my field people are definitely biased to what they think will work and you can set these things up so that your favorite diet is is sort of set up to have a higher chance of success and maybe maybe that's what was going on in some of the smaller shorter studies in in your study and i'm just thinking out loud here so i could be completely going down the wrong path but if so you've got this wide spread and let's just take the the low fat group for example but i could be talking about either and within that group you've got people who are really successful and people who are not uh i'm i'm assuming the people who were successful were consuming less calories per day on average than those who were not successful and i'm wondering was did you did you pick up on satiety or people that were successful sort of uh feeling feeling fuller on on less calories so a real challenge in my field simon is getting people to accurately reflect their calories that's where kevin hall whoops my butt all the time because he cooks it for them and slides it under the cage door and has them eat it and measures everything they didn't eat so people are notoriously inaccurate in reporting what they're eating [Music] when we looked at calorie levels for weight loss it wasn't related to weight loss wow right and it's like oh my but energy in energy out now that could be because that's wrong and the laws of thermodynamics are wrong or it just could be there's a lot of noise when people are doing this so imagine this somebody's in the diet for 12 months we don't check their diet every day we ask a month three days at the beginning three days at three months three days at six months and three days at 12 months if you look at people just for those three days the typical variability from one day to the next is 500 calories use somebody eating 1500 calories one day 2 000 calories the next day and 12 50 the next day and you come up with one average and you say ah that's what they were eating in july this is not really what they were eating in july that's what they were eating the three days we asked them so i'm not sure if that i i believe the calories made a difference we couldn't pick it up in an assessment they were doing but i love your insight so can i build on this satiety insight for a minute yeah let's build on that because i know anecdotally you know i kind of i listen to all sides of this diet was and there are people who swear that on a high-fat diet they're satiated and then there's someone else who's like well when i eat lots of starchy foods beans and rice i'm i'm full and i eat less overall so um you know i'm just wondering whether you think that plays a role yeah so there's a i have a slide from many years back that says protein is more satiating than carbs or more satiating than fat and to me that's that's a ridiculous statement because maybe that's if you ate pure protein pure fat and pure carbs when you're eating a mixed meal that has carbs and fats and protein yes there's there is a satiety factor with protein but carbs have fiber and carbs have a lot of water and what the bulk of the water is satiating and the bulk of the fiber is satiating fat delays gastric emptying it takes longer to get it out of your stomach that is satiating so i i really don't think it's fair to say there's an order to the macronutrients i think it's the types of proteins carbs and fats that you eat so simon in the middle of my study a group of three organizations the american cardiology association and the obesity society and the american heart association came out with this big thing about weight management there's a huge section on diet and so we're going to summarize all the weight loss diets that are and they summarized about 20 different kinds of diets and they said our opinion is that you can lose weight on any of the 20 diets but there isn't one diet that works for everybody and it does appear that for all of these the thing that's critical is restricting your calories but we did notice in the different studies that we looked at that there's two types there's one with a prescribed energy restriction and one with an achieved energy restriction okay i'm going to stop and see if this makes sense so prescribed energy restriction would have been okay hello mrs x and mr y you've come in today and it looks like you need some weight lose some weight and we have this archaic mathematical thing that a pound of body fat is worth 3 500 calories and you're going to have to have a deficit of 3 500 calories to lose that pound of fat and interestingly that works really well into 7 days of the week if you divide 3 500 by 7 days you need a 500 calorie deficit per day to lose one pound of fat and you might think you need to lose 50 pounds of fat okay so think about that 50 weeks of the year and you let's say you usually 2500 calories a day you need to eat one fifth less every day for the year and the first thing in their mind is like crap that sucks that sounds like i'm gonna be hungry forever i mean i was eating until i was full and now you want me to eat one-fifth less every single day oh no actually i'd like to lose two pounds of fat a day oh well then you have to have a thousand calorie restriction every day of the week per pound oh my god that that is so punitive that people freak out and they they can't do it so the other thing that i liked was an achieved calorie restriction because in diet fits we never told anybody about we never talked about calories we did not say you need to achieve this we said this is a low-fat low-carb diet i want you to go as low as you can in carb or as low as you can in fat and we don't want you to be hungry because if you're hungry we know you can't sustain that so you need to work that to the lowest carbon fat you can be with high quality foods where you aren't hungry and collectively they lost more than 6 500 pounds and we never gave them a prescribed calorie restriction and what the dietitians were telling me is exactly what you were saying is that some people were very satiated eating fewer calories on low carb while others were not and some were very satiated on low fat and others were not and that's too general of a statement to make because there were different way there's different ways to eat low carb and low fat you can choose different foods but if i walked away with any follow-up that i haven't quite got funded yet it would be to personalize satiety it would be try different breakfasts and lunches and mixtures of food and maybe eating something first and something second what kind of approaches can you personalize your own satiety so that you make these choices and you're full you're say [ __ ] and then then you get rid of this punitive aspect of the weight loss diet and you are enjoying the foods that you're eating and you're not hungry i think that's the silver bullet for me okay so so the diet fits i guess overall conclusion that that achieved calorie de deficit or achieved weight loss i should say that that you saw with diet fits was a result not of saying hey cut your calories to this but really just moving people to a higher quality diet and then you know what what you're talking about here is then does does satiety explain the differences between the groups and and perhaps there's room for people to explore which variation low carb high carb seems to fill them up with fewer calories you mentioned personalized nutrition i got a question on that seems to be a bit of a buzzword at the moment and and there's lots of people talking about it and and it sounds all very exciting and it kind of gets me thinking about the microbiome have you thought about microbiome differences between subjects does would that possibly predict how someone would go on on a different diet and what do you think about sort of personalized nutrition and the movement and all of the sort of testing kits and stuff that are popping up yep so i'm actually very heavily involved with two groups right now and one is my microbiologist colleague at stanford justin sonnenberg and his wife erica sonenberg so simon i used to call myself a feeder and a bleeder they say what do you do for a living well i feed and bleed people you know i'd get them to eat different food and then i take their blood and i look what happened to it now we always take their poop everybody gives us their poop i really thought this would be prohibitive we actually did this in the middle of diet fits we started doing this justin sonnenberg approached me said can i'd really love to play with some of this data do you think your participants would be willing to do that no poop is icky oh my god we're harassing him with surveys we're sticking him with needles all right you're a nice guy i'll ask him if anybody's willing to do it but i got to tell him it's optional because we're already doing a lot of stuff to him and i said okay people i got this colleague here he's willing to look at the microbiome and tell you what he can about it but we really don't know everything yet so i'm not sure what he's going to tell you 80 of the participants gave us their poop 80 wow i didn't even tell them what i could tell them it was just such a buzzword the prebiotic and the probiotic thing so we actually have a very cool paper coming out on july 6th on the microbiome and i can give you a hint of what it is we've got 18 people it was a pilot study to go from 20 grams of fiber a day to 40 grams of fiber a day and from less than one serving a day of fermented food to six servings a day of fermented food now those are small servings of fermented food like a bottle of kombucha's two servings half a cup of yogurt is one serving half a cup of sauerkraut or kimchi is one serving okay and so we characterized changes in microbiome changes in immune function it wasn't a calorie weight loss study it was very much an immune function study but we have documented in this field of prebiotics and probiotics we found some fascinating individual differences some of which appear it's a small early study appear to have been dictated dictated by what their microbial diversity was to begin with so justin has a whole bunch of data from traditional hunter-gatherer populations that the few that are left in the world and their microbial profile is completely different than the western world there's species that have gone extinct that don't exist anymore so he and i are looking at that so we have a very fun paper coming out in two weeks i started tweeting about it last saturday just to tease everybody and get them excited about this new study that i can't reveal yet because it will break the embargo but i'll bring up another study in the uk um the predict group that works with a for-profit company called zoe and i'm on their scientific advisory board and we meet i met this morning with them we meet every other week they have two papers published in nature medicine and they started with a thousand twins in the uk and so they had monozygotic and dizygotic twins and they were trying to look at a lot of their focus is this new thing with continuous glucose monitors and seeing how much glucose changes in response to the diet the foods you're eating and they were able to calculate not only the food that they were eating but their genetics their epigenetics their microbiome their sleep patterns their physical activity and so in one of these two papers simon they say okay i can't remember the exact numbers six percent of the difference is due to the genome and seven percent is due to sleep and eight percent is due to the microbiome and four percent is due to physical activity so they sort of tried to parse out all these things that have a difference on how different people respond to the same glucose source and load based on all these other parameters so that was the first paper and in the second paper that came out shortly after that they did a deep dive into the microbiome they looked at hundreds of different species and they showed different species that correlated well with good metabolic profile bad metabolic profile good glucose response bad glucose response and so yes i'm very much into the microbiome i will say that in that field of personalized nutrition there is a problem we've had multiple companies start up and go out of business already because they're ahead of the science they're saying they've been making promises of we if you just send us your poop we'll tell you what you need to do that we don't know yet but yes i am really excited about the potential of the microbiome but i'm actually a little terrified of the people who are making claims that go beyond the beyond the science that we have already because we're not there yet okay lots of good learning for the listeners just to be cautious of hype until the science catches up and to to make sure you're you're going to trusted sources uh and with that study coming out perhaps you can come back on and you can you can share the results with us at at some stage in the future we're we're sort of wrapping up here i'm conscious of time but i i have a couple other questions uh for you before we do finish up one is uh to do with the the sort of carbohydrate insulin model and that that's been put forward by carry gary taubs and and and others uh this is this idea that carbohydrates raises insulin leads to fat storage uh less energy increased hunger is there is there much to this model that remains unanswered or or would you say that it's now been refuted by science yeah i'm not in favor of the model so of all the science that's come out i think actually david ludwig does an elegant job of isolating this in some of his studies they're very contrived they're very controlled and he can pick up a signal in that kind of study he and i actually presented together at a conference and his conclusion seemed to be that because that model works then some people would do better on low carb and some people would do better on low fat and i said but i i just did that 600 person study and it didn't matter like i i know you're saying this works in this very controlled condition but if it's going to be useful to people then it should work in the general public and i didn't do a study as controlled as you did i did this big 600 person one year study it should have showed up if it was important i can measure a lot of the things that you're measuring not as well but in a general way if this is if this had been substantive i think we could find it and we couldn't find it okay so to to wrap this one up some take away messages from professor christopher gardner who's done multiple very well-known studies we've spoken about them here and and you're across all of the the literature work from kevin hall et cetera what what can we confidently say today we we know about nutrition and obesity what what do we still need to go out and explore and if someone's listening right now just as an individual where where should they start in terms of of better navigating their food choices for for weight loss and for overall health yeah so what i've come to i actually just had to do this they invited me to give an invited lecturer for the american heart association just before the pandemic hit and i was trying to put all that together and so i said i really think at some level there is a foundational diet i can even get two extremes like low-fat vegan and ketogenic to agree on at least four or five things okay less added sugar less refined grain lots of vegetables non-starchy vegetables so the broccolis the red bell peppers the snap peas the things like that okay overall more whole foods and less processed food particularly if you want to call them ultra processed that is like nothing's more contentious than low-fat vegan and ketogenic and you could get them to agree on that so and in the us i don't know about in australia but in the u.s we suck at doing that we don't eat many vegetables we eat a crap load of sugar in our fine grain we need a lot of ultra processed food and very few whole foods i think that's 50 of the metabolic and the health issues of the planet and if everybody's agreeing on that why aren't we focusing on the things that we agree on and then after that i draw this picture of concentric circles and say look okay you might not get all the keto and the low-fat vegan folks on board but i think we should have healthy fats avocados nuts seeds oils i think we should have beans i think we should have fruits i'm i'm even down for fish and eggs even though i'm a vegan myself most nutrition professionals agree on all five of those and then i think if you into types of whole grains and types of poultry you'd still get people to agree okay kentucky fried chicken not so good how about a pasture-raised chicken better whole intact quinoa and steel cutouts great refined grain not so good i actually think there's a huge foundational stuff area of foundational diet that everybody would agree on or almost everybody and then after that if if you got that right and for most people that would be a big shift i don't know if you would agree in australia but if you did those things absolutely here in australia is not much different 95 of australians are not eating enough fruit and veg and 42 percent of calories come from ultra processed foods so what i'd like to see is people do that and then mess with their personalization okay now i'm really more of a low carber or a low fatter or a higher protein and when i do it i'm going to do it with whole foods i'm going to do it with foods caught the right way i'm going to take the environment into account i'm going to take animal rights and welfare into account because it can all fit nicely together it could be consistent with my personal values my cultural taste etc so i really think there's room for personalization i really think the microbiome is going to be cool but i don't i'm very frustrated with like all this focus on the periphery when this stuff in the center that so many people agree on seems to get passed by the wayside oh i'm still waiting for the person to tell me that green jelly beans that i i'm genetically predisposed to do well with green jelly no no one's ever gonna tell you you're gonna do well with green jelly beans get them foundational diet right and then play with some of the other things yeah it's it's it's almost as if the conversation moves to the periphery because that's where it's a bit sexier to debate plant versus animal versus the middle the middle chunk that you're talking about which is the lowest hanging fruit is the biggest lever to pull yeah is it's it's not as appealing to to keep you know harping on about uh that brings me to my final sort of question here is around obesity overall and and speaking i guess zooming back out and not speaking so much on the individual level uh if if you could sort of wave your wand and and tomorrow the food environment globally changed would would based on what you just said then i'm assuming that it would it would just change the the availability of certain foods and and make ultra processed foods sort of take away foods less available yep it would change the types of food we grow more plants less animal more vegetables and a huge piece of that is actually the fun i'm having with chefs now so simon in the u.s half the food that people consume here is eaten outside of the home prepared by somebody else getting chefs on board because they can make this stuff taste great they can make a fabulous bean and rice dish that's moroccan spiced and seared vegetables on top and maybe not a huge amount of meat but two ounce strips of meat or fish or chicken or something like that i think the key is making it tasty accessible appropriately you know cost within the cost range of some people those are the bigger challenges actually beyond this low carb low fat protein thing so it's a food i'm glad you ended on this it's a food systems issue and so we need there's a lot of players who could come in and help us with taste cost convenience access and then i'll back them up with metabolism someday that's a great point we can't we can't lose the satisfaction for food and that's that's integral to building new habits right don't lose the joy and the pleasure when i gave that talk at the aha my last statement was don't forget there's so much joy and pleasure in food and if you're gonna leave that out we are not gonna get behavior change we're not gonna get meaningful behavior change and we don't have to we can do it well said thank you so much uh dr gardner big pleasure having you on the show and some some real incredible takeaways for everyone here so thank you keep up the great work and as i said i'd love to have you back on the show sometime in the future fun conversation you ask good questions so i'd be happy to be back simon fun to talk to you thank you for joining me for this episode and your interest in science-based conversation i hope you enjoyed it and found the information covered interesting and instructive if you did and you'd like to show your support for the show please subscribe to our youtube channel where you can stay up to date with new episodes and watch them in video format yes the full length videos please also consider subscribing to the show on the spotify and or apple podcast app wherever you enjoy listening to podcasts you can also 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Channel: The Proof with Simon Hill

Views: 60,459

Keywords: simon hill, science, nutrition, evidence, facts, diet, how to, vegan, plant based, healthy living, wellness, podcast, conversation, the proof, the proof podcast, plant proof, low carb, high carb, diets, fat, health, your body, personalized nutrition

Id: 4lauTeP17Q8

Length: 67min 26sec (4046 seconds)

Published: Thu May 26 2022