ZOE Science & Nutrition - What to eat for your health - according to science

Episode Date: January 25, 2024

From fads to fallacies, misconceptions have permeated diet narratives for decades. So, we dig in and demystify to forge a personalized path toward sustainable well-being. In today’s episode, Jonathan is joined by Prof. Christopher Gardner and podcast regular Dr. Sarah Berry. Christopher is a professor of medicine at Stanford University and the director of nutrition studies at the Stanford Prevention Research Center. Sarah is an associate professor in nutrition at King’s College London and chief scientist at ZOE. 🌱 Try our new plant based wholefood supplement - Daily 30 *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system Learn how your body responds to food 👉 zoe.com/podcast for 10% off Follow ZOE on Instagram. Timecodes: 00:00 Intro 01:00 Quick fire questions 02:30 Why do people go on diets? 05:07 Is it too late to change your diet? 06:28 How to adopt a better diet lifestyle in the long term 11:06 What are the worst diets for our health? 16:47 Why is there such a big gap between the scientific evidence and what we see on the shelves? 19:49 What should we do to improve our diet? 25:40 Do whole foods make us feel more full? 31:14 What does plant based mean and how does it tie in with the mediterranean diet? 32:14 Why is fiber so good for us? 35:50 Is it healthy to have fat in your diet? 37:03 Are reduced fat foods in supermarkets as good as they claim to be? 39:33 Low carb vs low fat study 45:07 What dietry revalations can we expect to see this year? 52:15 Summary 57:39 Goodbyes/Outro Mentioned in today’s episode:  Life expectancy can increase by up to 10 years following sustained shifts towards healthier diets in the United Kingdom in Nature  Popular dietary patterns: Alignment with American Heart Association 2021 dietary guidance: A scientific statement from the American Heart Association in AHA Journals Cardiometabolic effects of omnivorous vs vegan diets in identical twins: A randomized clinical trial in JAMA Network  Ultra-processed diets cause excess calorie intake and weight gain: An inpatient randomized controlled trial of ad libitum food intake in Cell Metabolism Effect of low-fat vs low-carbohydrate diet on 12-Month weight loss in overweight adults and the association with genotype pattern or insulin secretion: The DIETFITS randomized clinical trial in JAMA Network Have feedback or a topic you'd like us to cover? Let us know here Episode transcripts are available here.

Welcome to ZOE, Science and Nutrition, where world-leading scientists explain how their research can improve your health. I'm your host, Jonathan Wolff, co-founder and CEO of ZOE. Each day this week, we've examined the science behind the world's most popular diets. And today we conclude our series and ask the key question, what's the healthiest way to eat? Professor Christopher Gardner has been my guest throughout this series. And today we're also joined by Dr. Sarah Berry, and they'll reveal the answer on this show. Christopher is a professor of medicine at Stanford University and the director of nutrition studies at the prestigious Stanford Prevention Research Center. Sarah is associate

professor of nutrition at King's College London and the chief scientist at Zoe. Both Sarah and Christopher are world-leading researchers on how our diet impacts our health. Ready for the ultimate nutrition takeaway? Let's dive in. Christopher, thank you for joining me and Sarah today. This should be fun. I'm very excited. Why don't we start with a quick fire round of questions? And I think you remember the drill.

I do. This is a yes, a no. But for one question, I get maybe a little bit of an opportunity to expand if you're very good we know we like it's like the prize for professors for managing to keep the rules at the beginning is then they get a whole sentence at the end he doesn't let me have a whole sentence you're very lucky christopher so can i improve my health if i change what I eat? Yes. Are some popular diets harmful to your health? Yes. Is there one diet that works for everyone? No. Should men and women eat the same diet? Yes. Is there one food that can drastically improve my health? No. See, that was easy. All right. Oh yeah. That was very easy.

So now you get a whole sentence. What's the biggest myth about healthy eating that you often hear? The biggest myth is that there is one diet for everyone. If we just could find it, if those scientists would just finish their studies, they'd tell us the one diet we all need. Well, that almost sounds like an ad for Zoe, so I love that, Christopher. So look, throughout the last week, we've been discussing popular diets in this series of sort of short daily episodes. But before we draw sort of our conclusions from this and hopefully help everybody understand how they can improve the way they eat to improve their health in 2024, I actually want to go right back to the start and ask you this.

Why do people go on diets? Oh, great question. They intuitively know that what they're eating has an impact on their health, and they're not happy with their health. There's so many people who have health conditions, don't want to be on medications, want to lose some weight. It's pretty obvious for most of them that it's related or could be related to their diet. and so what are the biggest sort of myths or misunderstandings that people are then suffering from when they decide hey i'm going to go on to a diet now to fix my health so for me the simplest answer would be there is a diet that i can do short term that i will eventually get to go off of and i'll be all set once I master that for now,

but then I'll quit. And why is that a myth, Christopher? Well, because for anything to work, it only works as long as you're doing it. So once you go off, the weight comes back on, the cholesterol goes back up, the glucose goes back up in the blood. So it only works as long as you're doing it.

So you have to do it forever if you want it to work for your life. Which is quite a challenging idea, isn't it? It's sort of saying, hey, you've got to make a lifelong change to the way you're eating. And when you think about it like that, it also sounds really scary. There'll be probably people listening to saying, well, you know, I can't do that. So therefore I should just give up. Is it as bad as that?

Oh, it's not as bad as that at all. I have a PhD in nutrition science. I'm still changing my diet to this day as I do more studies or learn of a different cultural food attribute that I like. You should be kind to yourself. You should let yourself experiment. I mean, the beauty of food is, and let's make it either eating or cooking. Let's say you burned this recipe. Oh, you're screwed. You'll never make that recipe again. It burned.

No, you burned it. Turn the heat down next time or add a different ingredient or go slower. So the beauty of food is you get a do-over every day you want. I love that. And so I think one of the things that we hear often from people is a concern that it's too late. They've been eating in a particular way for too long. And so they are 40, 50, 60, 70, 80. And therefore, it doesn't matter anymore.

I think about my parents, actually, as I think about this. It doesn't matter anymore because it's all done. And so it doesn't make any sense to change what they eat. Are they right? No, for all these things that are risk factors that clinicians measure, again, this is blood cholesterol or blood glucose or weight, whatever it is. Yeah, you can always enhance your physical abilities and your long-term health, no matter what age you approach this. Yeah. And there's some really interesting research, Christopher, that came out a couple

of weeks ago, you might be aware of, where they looked at how many extra healthy years people had that went from a very typical UK-US diet to the recommended diet and to what they called a longevity diet, which is basically combining all of what's up here in your head and applying it to people's diet. And they found even when people went on to a longevity diet at the age of 60, they still gained many extra healthy years. And I think that's really encouraging that people should really focus on actually at any time, I can still make a huge difference. Yeah, very encouraging. It's amazing and incredibly positive, I can still make a huge difference. Yeah, very encouraging. It's amazing and incredibly positive, I think.

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And you can get it for free. Simply go to zoe.com slash free guide or click the link in the show notes and do let me know what you think of it. Okay, back to the show. And so you were talking about this idea that people need to sustain this life, this lifestyle sort of permanently.

And so I guess that has implications for the sort of diet that people, you know, should be adopting as we're discussing this today. Yeah. You have to like it. You have to enjoy it. So I feel like... Which sounds a bit radical, actually. I'm laughing, but that's because I feel like I grew up with diet culture.

And I think many people listening to this did. And the whole idea of diet culture is quite linked to the idea of calorie counting, which we touched on. It's like you're supposed to suffer in order to try and improve your health, which is also why you can't properly do it forever. But I'm sort of laughing because this idea that you might enjoy your diet feels like the opposite of what I was taught. Yeah. So let me give you one of my favorite new phrases. So after doing many studies,

and I'm just going to mock myself here, and I'm sure Sarah could agree. If we're trying to get an answerable question, we'll focus on this one thing. And okay, so isolationist, reductionist, this fiber works, what's the best source of fiber? Cardboard, we've given you cardboard. It has lowered your cholesterol. Go forth and eat cardboard. I don't wanna eat cardboard,

but I showed you it lowered your LDL cholesterol. So I've been working with chefs a lot lately. And I've been working with a lot of chefs that are interested in plant-based diets. And Greg Drescher is one of the leaders of the Culinary Institute of America in the U.S., one of the largest cooking schools in the U.S. And he introduced a term to me years ago about unapologetic deliciousness. First, it was craveability, which I really liked. I thought people are going to like that. But when he said unapologetic deliciousness, I think a lot of people would like to eat that way. But it struck me in a particularly strong way because I remember myself for years

apologizing. I found the cardboard will help your LDL. I'm scrunching up my face because I'm sorry that I'm asking you to eat cardboard, but it works. I proved it in an NIH-funded study, in a randomized control trial, and I'm sorry it's so painful and restrictive, but it's the truth. Greg Drescher said, you know, we can make anything taste good. We'll make this Mediterranean, Middle Eastern, Latin American, African dish. Tastes great. It'll be plant-based Middle Eastern, Latin American, African dish. Tastes great. It'll be plant-based. It might have some animal source food, but a lot less than you

eat in the U.S., but it'll be amazing. I thought, ah, I want to stop apologizing. I want to say this is unapologetically delicious because in terms of maintaining something long-term, that's what you want. You don't want to be punished and penalized your whole life. Yeah, I'm a great believer in if a food's too healthy to be enjoyed, it's just not healthy at all. And a big problem we have isn't just that we're eating the wrong kind of food, it's that we are not adhering to any of the kind of recommendations because, like you say, that lots of these foods are, you know, they don't taste great, they're very restrictive, these kind of diets

as well. And in the UK, less than 1% of people actually follow any kind of healthy eating guidelines. It's the same in the US. And so there's no point telling people to go on this kind of diet, to eat these kind of foods if they taste rubbish, because you won't adhere to it long term. And that's why all of these, or many of these diets fail. Sarah, I love that. And I would like to pull you in as a fellow geek here. We run studies. We randomly assign people. And I think a huge problem that people have in their frustration with nutrition is what

looks like misinformation in the scientific literature and the media that covers it. One day this one works and the next day it doesn't. And the word that really struck me that you just mentioned is adherence. And we both go to great pains to have them self-report what they're eating. And that's better than not self-reporting. But at some level, I'm sure some of them feel like they told me to eat this and I better tell them that I did because I'm in the study. And they didn't really eat it. And what we're really missing is the nuance of individual variability and how each person in that study followed it a little differently. And as frustrating as that is, it's kind of fascinating to think of the personalization

opportunities there that are always coming up. So we covered a host of popular diets throughout the last six days, and some of them were really extreme and restrictive, which I think is interesting given this discussion we're having about the challenge of something that's restrictive. So like the carnivore diet or the keto diet, or indeed, I think you were talking about this very low fat vegan diet as well. And then there is calorie counting, which basically says you've got to restrict yourself. The heart of what you're doing is restriction. And then there was the Mediterranean diet, which certainly the way that you were selling it to. And then there was the Mediterranean diet, which certainly the way that you were selling it to me, Christopher, I could taste it even as you were talking about it and felt a lot less restrictive. So I'd love to draw some conclusions

about these diets before we then talk about, okay, what do you think is best? So maybe start with, what are the worst diets for our health? The worst ones are the ones that are most restrictive and most animal-based, which is the highest sources of saturated fat and the lowest sources of fiber. And why is that? Why do you feel like that's what makes them worse, the restriction and the animal fats? So the restriction, the part is it's hard to maintain. Any restrictive diet is hard to maintain. But of all the things that we can come up with in nutrition where you can actually trace it back to a nutrient, the three easiest ones, so actually let me bring up a third, would be saturated fat

for your LDL cholesterol, bad. Fiber for your microbiome, good. And added sugar and refined grain for excess calories and a poor metabolic effect. So I will say that pretty much all the diets that are out there, and we've just published an American Heart Association overview of popular diets, All of them, even our favorites and our least favorites, said less added sugar and lesser fine grain. Let's have a kumbaya moment. Can we just have a big hug and pat on the back? We have consensus on that point. And in this paper that we just wrote, we tiered the diets in four tiers, and the lowest tier, just in terms of matching up with American Heart Guidelines for being a heart-healthy diet, keto, paleo, and Atkins were all in the lowest tier. Published paper.

I think another thing that a lot of people feel is, particularly at this time of year, they feel, you know what, I think I sort of overindulged in, you know, November and December and I'm waking up in January and I know that that has impacting how I'm feeling. So I know that what I'm eating along with probably other aspects of my lifestyle to do with how much exercise is really affecting my health. And I, and I want to feel better now. Like I really want to feel much better. I want to live many more healthy years in the future. For many people will say, I'd really like to lose some weight because I feel like I can see that this has been sort of slowly going up. And so they would like to be able to do something which is going

to give them a fast effect on that. So I think to me, not being a nutritional scientist, there's a lot of logic for that. And so I guess, what would you say to people, therefore, as they're thinking about how to change what they eat, given, you know, that's what they want, and they don't want to be told, well, you can wait 10 years before anything happens? Yeah, well, a lot of the things that we do in diet work in four to eight weeks. If you wanted to change cholesterol, blood glucose, inflammatory markers, microbiome, a lot of things like that can change in just weeks. We've just published an eight-week study assigning identical twins to vegan or omnivore. And the studies were there at four weeks. And so a lot of the participants looked at that and said, wow,

this is amazing. I didn't really appreciate that it could happen so quickly. And so you're saying, people listen to this, you can really change how you feel and even markers of your health, things that a doctor could measure in your blood in just a few months without having to go for these sort of extreme ketogenic diets or something like that. And I'll get Sarah to chime in here. So you do get bigger effects the bigger the change that you make. But my worry is the bigger the change that you make, it might be the least likely that you will continue that change. So my personal approach for most people say, think of the worst couple of things that you do and just get rid of those and find something to replace them.

Or find something that you already do that your nutrition consultant likes and do more of that. Take something more reasonable. But if you really wanted something quick, you could see it if you made a big change. But if you want it to last, it should probably be slower. Just like weight loss issues. If you see anybody losing weight very rapidly, they're very likely to gain it back. A more healthy thing is a pound a week over a long time will last longer. And I think to focus on one change that is going to have that bigger size impact is really

important. And we see in our studies, for example, cholesterol can change in 10 days. After two weeks, you see quite a big difference. After four weeks, it plateaus. And so any dietary change, if you were to go to the doctors and have measures done, you do see that change. What we don't see is obviously externally the change, and that's the problem. So people maybe not realizing, wow, you know, making these changes have really had a big impact internally on my health. Yep. So before talking about what people should eat, which is obviously what they're really interested here, I did want to ask about

why there's such a big gap between the scientific evidence that, you know that both of you talking about right now on topics like calorie counting and sort of low fat food. And then what we see on the food labels when we go to the grocery store or official guidelines where basically, I looked again this week, you walk in there and everything still says low fat on it unless it says high protein. And there are calorie labels everywhere. And yet you sort of demolish both these approaches to thinking about how we should eat. Yeah, the communication part is the hardest. So the studies that we do are complicated.

They don't really have one simple interpretation. And part of the reason for the labels is the food industry recognizing that they want a little bigger share of the market's stomach. Just a piece. I can answer my shareholders if I get that. What's the current thing they just said? Oh, they said that. Okay, I'm going to add it to the label. And shoppers want something convenient, like, oh, food is confusing. I'd really love to go into the store and have a simple thing that will help me with my choices. And sadly, it isn't simple. I know they want that help. I know they want it to be straightforward. And I know the food industry wants to make more money.

And it works. Some of that advertising works. And we're just caught in a bind trying to communicate what we find in our studies and make it simple for everyone when it's almost never that simple. Sorry, listeners. Yeah, I think this is the real challenge. I find that we know that foods have thousands of chemicals. We know that these chemicals are packaged in, you know, the structure of the food. You know, I'm particularly interested in the food matrix, so how the structure of the food modulates the health effects of that food. None of this can be captured on those food labels. But we as nutrition scientists need to make sure that our message is very simple to people, but because of this complexity of food, but also the complexity of how we as individuals process the food, it's just too nuanced to communicate in a food label.

And so it's a real challenge that we have, and I don't know how we can tackle this. The answer is just to get people to think more critically. I mean, actually, I think this is maybe an odd twist and you wouldn't have seen this coming. I think food is an opportunity for people to think more effectively critically in ways that will help them in the rest of their life. I don't understand politics. I don't understand war. I don't understand this other thing. You're not thinking critically. There's more than one side to this argument. So think through this logically, recognize the limitations, recognize the strength, and make the best choice you can today.

Can actually be very empowering in the long run, but you do have to engage. So I'd love to start to talk about what people should do. So we've sort of said, hey, there's a whole bunch of diets that don't make sense. And in fact, the whole idea of a diet, something you do for a period of time doesn't make sense. You've got to shift to thinking about like, how am I going to eat for the rest of my life? I'd love to talk some more about therefore what we should eat. And Christopher, you said to me, you know, before this recording, like the number one thing people say to you is, Doc, what should I eat? So let's, you know, maybe sort of make that step. You know,

what's the starting point for answering that question? Okay. And I think Sarah's going to be with me on this one. My first answer is it depends. Absolutely. My next two follow-ups are, please tell me with what and instead of what. And where are you now? So, you know, if somebody says, I'm really thinking whether I should eat eggs or not. And I say, well, what were you going to have otherwise? And they said, well, I was going to have steel cut oats or eggs. I said, well, I don't know. What were you going

to have the eggs with? I said, well, I was going to have sausage and bacon. I said, ah, okay, so I really think you ought to have the steel cut oats instead of that. They said, oh, I didn't mean that. I meant a veggie omelet. I said, oh, veggie omelet, steel cut oats. Yeah, not too bad. Pretty equal. I'm fine with that. Or they said I was going to have a Pop-Tart. I said, oh my God, have the eggs. God forbid you eat that Pop-Tart, right? And so if you put it in the context of with what and instead of what, they could often answer their own question for you, knowing that part. Yeah. And at Zoe, we often talk about swaps. So it's a simple way of really explaining what you've just, or putting into practice what you've just explained. So we say, okay, this is what you're currently eating that isn't so healthy. This is a healthier swap.

So it can be used in the same way because we have to be practical. There's no point recommending either food that people don't like, like we've already said, but also that isn't used in that kind of traditional breakfast setting or snack setting. This really ties into, there's been a shift in American dietary guidelines. So every five years, they update the dietary guidelines for Americans. And two or three cycles ago, they made sure to talk about shifts. So for many years, American nutrition was about penalizing.

Don't eat added sugar. Don't eat saturated fat. Don't eat salt. But they didn't tell them what to eat. And a colleague of mine, David Katz, loves to phrase this as Americans are incredibly clever. They will find an unmeasurable number of alternative ways to eat poorly once you ask them to avoid this. Oh, I found another way. That's poor too. Oh, I found another way. Well, that's poor too because we didn't tell them what to eat. It was easier to tell them to avoid this. Oh, I found another way. That's poor too. Oh, I found another way. Well, that's poor too, because we didn't tell them what to eat. It was easier to tell them to avoid that.

And I think you touched on this a bit when you were saying that the Mediterranean diet was the one that you were most positive about in terms of the different diets that we've unpacked over the last six days. What is a good way to eat in 2024? Yeah. And there's different names and different approaches. If I had to ask in the three seconds, I would say whole food plant-based. And whole food means just not the processed and refined things. So you take the wheat berry and you've turned it into flour for bread. No, eat the wheat berry. You've taken the brown rice and turned it into white rice. You've taken the soybean and turned it into soy

protein isolate and added it to a protein bar. No, no, you should eat the whole soybean. So that's what I mean by whole food. And plant-based means you don't have to be vegan or vegetarian here, but boy, people are eating a lot in the U.S. in particular. We eat more meat than any other country in the world. So you don't have to give up all of that, but give up a lot of it and have a plant-based meal. This is where the Mediterranean sort of grain and bean-based dish, which globally have been staples for many, many years in many cultures,

partly because they store easily and they're economically feasible. Grains and beans are pretty simple food bases to start with, and that's why spices are so important. So get Moroccan spices, Mediterranean, Latin American, Middle Eastern, Asian, spice them up. And then you can add smaller amounts of fish or poultry or pork, something in smaller amounts of meat. So the chefs that I work with for this unapologetic deliciousness do something called the protein flip, where the base of the meal is grains and beans and veggies. And then meat becomes a condiment or a side dish or just a small portion on top of that. So to me, that's very Mediterranean and has lots of flexibility for enjoying what you're eating. And in a way that sounds very simple, but I think for a lot

of people listening to this, also quite unclear in comparison to diets where based on this idea, you have to remove this thing because it's sort of killing you or causing problems, or basically everything is about calories. You know, you're measuring your calories. So obviously you're not going to get better unless you reduce your calories because that's what it's about. So maybe we could take those two parts one after the other like why is whole food better than processed food after all i chew it all up and it goes in my stomach as i always i remember discussing this with my children at various points you know when it's all messed up they're like oh it's okay it's gonna be messed up in your stomach anyway so you might as well eat it

that way so why is it that um we can't have it all nicely sort of processed and prepared by the food manufacturers? We're busy people and we have to have this sort of whole food thing that you just mentioned. Okay. So I'm going to ask Sarah to help me fill in on this because satiety and satiation are huge factors in all this that are harder to study than we think. Yeah. And Christopher means how full you feel, because I know you would want us to give a simple term for that. And so this comes up for me all the time, thinking, so one of my favorite authors is Barbara Rawls, who wrote a book called Volumetrics years ago.

And it was the volume of the food that was filling people up. And the volume tends to be much higher if it's veggies and beans and grains than if it is cheese or meat or dairy. And so eating this very satiating meal so that you get full quicker and stop eating and that it's longer till your next meal really helps here. As scientists, this is very hard to study. So I've done a number of studies where I've got diet A and diet B. And what I'd really like to know is after three months in the study, how hungry were you in March?

How hungry were you in April? We don't have any metrics like that. All the metrics for this concept of satiety are, I gave you a standardized breakfast at 8 a.m. It had 600 calories. And two hours later, I had a line from starving to very full. And I marked on the line where I was in between. Okay, how does that work for April? I can't tell you for April. I can only tell you two hours after the standardized 600 calorie breakfast. And so it's actually a harder concept to measure than you would think. I mean, you can just qualitatively say, so how hungry were you? And people give quite a varied response. Well, I have some good news for you. In our Zoe app, every week we ask people weekly,

not just after each meal, how hungry have you felt this week? So we will be able to look at people's diets, but we have also collected data in that old-fashioned way, but where they do on a scale say after a meal how hungry they feel. I often think about the health effects of processing also around the idea that you've talked about, like the instead of what. So what's happening is we're removing some of these great nutrients, you know, the fiber, some of these bioactives that we often talk about as nutritionists, so polyphenols, we're adding in the bad nutrients, the salt, the sugar, you know, the refined carbohydrates, the saturated fat. We're eating these foods more

quickly. So not only are they more energy dense, like you say, filling up our tummy, but we're eating them so quickly that that's another reason our fullness signals aren't getting to our brain in time. And all of this means that we're over-consuming the wrong nutrients. Dare I use the term nutrients? Because I know you, like me, are very food-based rather than nutrient-based, eating less of the good nutrients and eating in the wrong way as well. Yep. And Kevin Hall has done a nice study like that. Again, they were people who were confined and a lot of control was over this, but had an ultra-processed versus a minimally processed and timed how fast they were getting the calories. And much to your point, when they're eating the more heavily processed food, they're eating more

calories faster. A 50% difference in the rate at which they ate those calories between the ultra-processed and the unprocessed foods, which led to about 200 calorie difference, I think, over the day. And it was hard for that message to get to the brain in time to stop you. So I think you're saying there's like two effects here. One is that the more processed food, I'm just basically going to eat it faster. It may even be designed so that I don't want to stop eating it. So I'm just going to end up consuming more calories. But there's the second part, which is you're saying the food is

just worse for me when it's been really processed, that you're losing a lot of things that now scientists understand are really important to us. And I think, Sarah, you mentioned, you know, like the thousands of chemicals in our food, right? Because most people listening to this are like, aren't there like seven vitamins? Isn't that basically what there is in food? Because you see them, you know, on the great big labels on breakfast cereal, like, hey, this vitamin and this other one has been added. I've got a colleague named Michaela Kiernan who approached this in a wonderful way. She said, okay, pick this thing that you think is not so good in your diet that you'd like to replace and try at least five things to replace it. And if you're going to replace it,

replace it with something that is as good or better, as opposed to there's a thing I want to get rid of. I tried an alternative and it wasn't as good, so I didn't do it and I went back. It takes some time. But once you've put in that time and you've replaced that thing with something as good or better, you have a change for the rest of your life that you made. And that's, again, now it's part of your lifestyle, you know, where to shop for it, you know, how long it takes to make it, make it, what you need ahead of time. And for me, that's why it's important that this is a journey and not an overnight thing. I tried five things. It took me weeks to look for other options. But now that I've got it, I mean, think of everyone who, regardless of what their diet is, if they were pushed,

there's three or four things that they know they like that they could get quickly. And so to tell them, don't do that anymore, have this other thing. Oh, the other thing isn't going to be nearly as quick as a convenient. Of course not. Not until you get accustomed to it. And then it will replace that and it'll work just as well. Now you touched on sort of, I think the first part there for what you described, sort of whole food, not processed and how, you know, if this food ends up being really processed, like one, we just digest it

really fast and you get these great big blood sugar spikes. And we've talked about some of the negatives on that, I think, over the last few days. And then I think, Sarah, you're also talking about how you lose a lot of things that are stripped out. Can we talk a bit about the other part? So plant-based, which I think, you know, for some people listening is like, what does that mean? Like plants are things in the garden and why is that a good thing? And how does that tie in with the Mediterranean diet you talked about before? Sure. Cause the, I mean, some of the key things that we came up with from the reductionist days was high saturated fat versus low saturated fat or fiber being good

for you. So plants have fiber. Animal foods don't have fiber. Very few plant foods have saturated fat. All the animal foods have saturated fat. So if you just wanted to start overly simplistically, that's a place to start to include more plants in your diet. And why is the fiber good? Fiber is good for the microbiome. It's the food matrix. It slows the digestion so that the carbohydrates that you are eating that are going to turn into blood glucose appear slowly over time,

satiating. It'll help you feel full sooner. It'll last with you longer. This is something we're really interested in as well, because we know that fiber is like the party food for the microbiome as well. And that's where we see the strongest signal. So we see that the association between fiber

and a healthy microbiome is incredibly strong. We know that fiber is one of the single nutrients, and I know again, we hate to the single nutrients, and I know, again, we hate to talk about nutrients, that is associated with improved health. And I think that one of the strongest reasons is because of the impact it has on our microbiome, as well as these other mechanisms. You've done some research as well, haven't you, looking at this? I'd love to hear those results, because I know it's quite a new study that's come out. Yeah. So we've been messing with fiber and fermented food and the microbiome and trying to characterize this. We're actually way behind you. So we look to some of your publications to see what you're coming up with, because we don't, from my perspective, our lab hasn't generated

a list of the top microbes or a list of the different kinds of fiber. So at the moment, we're kind of stuck with, well, since we're not sure, have a variety of fibers because the fibers that are present in wheat versus nuts versus beans are not the same. And again, sorry, but it's complicated. So you can't just pick one fiber for one strain of bacteria that you're trying to look at. The growth or the bloom of one of those bacterial strains has an effect on the rest of the community. But that's what I love about Zoe is how you're after that. You're after the complexity because you can measure the fibers and you can measure the microbes. And this is why we talk about diversity so much, because we know that there's no point just focusing in on one fiber or one aspect of a food, that we have to

make sure we have a diversity of all the different bioactives and all the different kinds of fibers. So Sarah, for someone thinking about this right now for what that means for them to eat, because it sounds cool, right? I want to support my healthy bacteria and get all those health benefits. But what does that mean if I'm thinking about what I'm eating? What does that imply? So when we talk about a diversity of food, we tend to be wanting people to have a diversity of plant-based foods. So we talk about having, eating the rainbow. So eating the rainbow means that you're getting lots of different types of polyphenols. Polyphenols are these magical bioactives that are in food that give food their pigment, so their colour.

So by getting a whole rainbow food, you're getting different polyphenols, but you're also going to get a variety of- I'm guessing my red pop tart, coming back to a previous comment, that's probably not the polyphenols that are colouring it. Am I right in guessing this? No, I'll use Christopher's terminology. So whole food, plant-based are the ones that we want to be encouraging. And having a diversity of different plant-based foods,

because exactly like Christopher said, they have so many different types of fibers. And because we know that different bugs, different bacteria feed on different fibers, we want them all to have a party. And we want them all to be growing and all be producing the chemicals that we know have such a wide impact on our health. The show you're listening to right now that's providing you the latest evidence-based health and nutrition information from the world's top scientists, while making it takes a lot of time. We think it's well worth it, all in the name of improving your health. All we ask in return is this.

Send a link to this podcast to someone you think would benefit. And if you haven't already, click follow this podcast wherever you're listening right now. Okay, let's get back to the show. And before we move beyond this, I'd love maybe to talk for a minute about the fat side of this, because one of the things that we touched on during the last six days is how many people still basically feel that they're really averse to adding fat into their diet because they were brought up when it was, I think about my own family, you know, I was brought up, there was super low fat diet as I grew up because my father had high

cholesterol and he was told by doctors, you know, even before I was born, you need to eat low fat. So I definitely grew up in that environment where I still find in a way, the idea of like pouring oil over my food, which I do a lot now, but it's still like, it still feels like a little naughty, which maybe it's one of the things that makes it, I enjoy still feels like a little naughty, which maybe is one of the things that makes it, I enjoy it. And Sarah, I know this is one of your core areas of study for the last 25 years. If people were understanding what healthy fats are, and they were also looking to understand what they could add in, what is the latest science saying? Yeah. And this is a nice way to tie back to fiber. So plant foods rarely have high saturated fat. So if you're getting an avocado, you're getting fiber. If

you're getting nuts, you're getting fiber. Seeds, you're getting fiber. Eating olives, you're getting fiber. So you could get the fiber and the monounsaturated fats. And those were all quite high fat foods. So you're describing even though they weren't actually oils and they weren't maybe what people think of necessarily as fats. I was listing all foods, plant-based foods that have a fair amount of fat in them, nut butters that you could spread on things. I'm saddened that there's still this perception that low fat, reduced fat, no fat alternatives are healthier for you. And I see these in the fridges of people that I know are on weight loss diets. And honestly, it worries me that there's still this perception out there that if they have a low fat food, they're going to magically lose weight. And also don't realize that by a food having low, no or reduced, something's come out

of that food. What's gone in to replace that? Yes. Because of this low fat stigma, very focused on low fat yogurt, which happens to be full in the US of sugar. Like they'll have a fruited yogurt. This is passion fruit or guava or blackberry or passion fruit, blackberry, guava yogurt. And you look and it's full of sugar. It's like a sugar delivery system. It's like they took out the fat. And this is not healthy for you? They took out the fat because people are afraid the fat is bad for them.

And they filled it with sugar, which is probably worse than what they started with. And I think this is a great example of how our knowledge of food and the health effects of food and nutrients is evolving so rapidly. So there was evidence to show that dairy fat was bad for us, that it's high in saturated fat, that maybe a high total fat intake when it comes predominantly from saturated fat is bad for us. We now know from randomized control trials and other evidence that fermented dairy fats, so fat in full fat yogurt, fat in cheese, isn't bad for us. It doesn't raise our cholesterol. And it's very difficult to keep up with how science is evolving.

And this again is the challenge. And so I think this is why there's these kind of products out there that's preying on people's ignorance, unfortunately. But also, Christopher, going back to what I know we've been talking about earlier, fat makes food taste great. It carries the flavor. It has that creamy mouthfeel as well. And so listening to all of this, you could start to say, okay, so there is one diet, one way of eating, which is the best for everybody. Is that the conclusion? You're really pushing on this one, Jonathan. So tell me about that. And I know, Sarah, you were saying earlier, we have to mention one of

Christopher's fantastic studies exactly around this. Yeah. So we did a large low-carb versus low-fat study. And the approach we took, I think, was fantastic. I'm very proud of this. We wanted it to be a healthy low-carb and a healthy low-fat. Because when you just say low-carb or low-fat, how low and which foods, I can easily come up with a poor and a better diet that both carry that name and are low in carb or fat. When you put good foods, this is where the personalization thing comes in again. After seeing many studies go back and forth on low fat and low carb,

we did a study that lasted a year, a weight loss study in 600 people, which is a pretty unusually high number of people. And the weight loss difference was virtually identical in the two groups after a year. But the most stunning thing for me was how variable the responses were to the two diets. So in both diet groups, somebody lost 60 pounds. In both diet groups, somebody gained 20 pounds on a weight loss study. Oh my God, they gained 20 pounds in a weight loss study. So there were like some people who were put on low carb and put on weight, and there were some people who put on low fat and put on weight and the reverse. And the reverse.

And I was not calling out outliers. So what's really fun is we graphed for every one of the 600 people, 300 on each diet, you know, what was the result for each person? It was absolute continuum. Somebody lost 60 pounds. Oh, should we do kilos here? No, let's talk pounds. 60 pounds. Somebody lost 55, 50, 45, 40, all the way to the other end of gaining 20. Why? They got the same advice. So how could it be these two diets which were quite different? They were very statistically different in terms of carb and fat. So what's the answer? So the answer is we need to find more areas of personalization. In fact, our study was done to test two of those areas. It was never done to test low-fat versus low-carb. We thought there might

be a predisposition that people who are genetically predisposed because of some genetic mutation one way, or the group that was the most insulin-resistant versus insulin-sensitive would help explain some of this. And the literature supported that that might be an explanation for the variability. Neither of them work. So, Sarah, what's going on? Well, I just want to say, Christopher, what I love about your study is that if you look at the average change in weight, they're exactly the same between the two groups. And I use this in a lot of my teaching to show that we need to move beyond looking at the average, looking at the mean of the population. And this is what dietary guidelines are based on, the average response to food. And your study really

clearly shows that if you look at the average, they're exactly the same. But if you look at how each individual response is hugely different, and we see this with our ZOE predict research, that we see a 20 fold difference from one person to another in their blood sugar response to exactly the same meal. So, for example, we fed people exactly the same breakfast. We controlled as many of the other conditions that we know impact your blood sugar response. So they'd fasted overnight. They'd done no exercise. And we still found this 20-fold difference, which is huge, to giving them exactly the same breakfast.

And this is what we've been exploring, as you know, with all of our ZOE research. What's causing this? How can we disentangle this, given that the food's so complicated, we're so complicated, our biology's complicated, and how we live our life is so complicated? Yep. And you won't know tomorrow, right? Oh, you're going to know the next day. Okay. So you won't have all the answers soon. In the meantime, everybody, if they chose a whole

food plant-based diet, some are likely to do better on higher fat and lower carbs, some just the opposite. That's not bizarre. That's almost, that should be expected. So for now, they shouldn't just throw up their hands and say, oh, there was no difference on average. I'm going to go have a pint of ice cream because the nutrition scientists can't agree on anything. No, no, no. If you talk to us, we actually agree on a lot of stuff. It's just nuanced and we are waiting to do some better studies. So you should still eat well today. And we have some basic guidelines, but stay tuned because we have some exciting developments in work. is food is really complicated and understanding for yourself how to take the way that you eat now and how can you adjust it in a way that's healthy for you and navigate the complexity in the grocery

store and how you cook it given all this complexity about like is that really a whole food is that really processed not processed is hard and i think this is one of the reasons that you know we see the level of success that we do for people following, you know, their Zoe program is this ability to get this like day by day guide and help you to understand exactly how these meals really score for you allows you to, you know, increase your chance of success because it really helps you navigate something that is complicated. Before we wrap up, I feel like we focus a lot in a way on this past history of diets, which are about like this

particular foods that you put in or not. And I feel like a lot of the focus on the sort of ongoing nutritional science is more about sort of the ways in which we eat. And so I'd love for you to maybe just pick out a couple of the things, you know, that you're really excited about that I suspect we may be talking more about this year? So Jonathan's being very kind to me here, Christopher, because my new passion is all around how we eat. And I've been working very hard to convince him that this is something that we should focus on in the ZOE and we are now focusing and it's now becoming part of our advice, which I'm really proud of. and so I'm a great believer in

as well as what you eat as well as who you are how you eat is incredibly important and it's something I think we as nutritional scientists haven't thought enough about in the past and so we know from our own research how much sleep you've had impacts your blood glucose blood sugar response the next day we know that time restricted eating is a really simple way to be able to improve your health without changing necessarily what food you have and i don't mean time restricted eating having like a six hour really restrictive window even having a 12 hour period that you don't eat overnight has incredible health benefits and we know this from the big if study our big intermittent fasting study that we did. We know that how fast

you eat food impacts your health. And we've actually published some research about looking at how people on our ZOE predict study who ate fast versus those who ate slowly had different blood sugar responses, different visceral fat, different body mass index as well. And we know the time of day is important. So we know that for lots of people having carbohydrates earlier in the day is more healthy for you than having carbohydrates later in the day. Again, it's not the same for everyone. But if we can combine all of this, I think this is a really simple way that we can also, again, optimize people's health, but allowing people to make some small changes that fit within how they

live their life without over worrying about trying to get everything perfect so for example just not snacking after eight at night trying to put your knife and fork down between each mouthful at the dinner table and you know trying to be a bit careful having really refined carbohydrate later in the day and adding some of these in and to mix as well, I think is a really magical way that we can easily improve our health as well. I wonder what your thoughts are on this. Yeah. And the key to that is having large bodies of data over time where you see people doing different things. So I think you're doing some excellent work that's going to lead to some randomized controlled trials where you say, ah, we've got a signal from this data set that we

have that this thing makes a big difference. And it looks very compelling, but we could do a new study to test that one thing. But to get that, that you have to have the ideas. So you're generating your own hypotheses for the future. I agree. This is a fascinating area, and it reminds me of, you know, if you're talking time-restricted or those kinds of issues. I often give a lecture where I'll say, you know, how many of you are useless unless you eat breakfast? And a whole bunch of people raise their hand. How many of you skip breakfast and have absolutely no problem, and you're fine? And the other half raises their hand. What is this thing about breakfast is the most important meal of the day? People are very different in when they start their breakfast, what they have for breakfast,

when's their first eating episode. So we know that's very personalized. And so I would love it if you guys can use big data sets to pull together, ah, there's some hints at who those people are, and you might want to test it on yourself. And we'll do a study in the future, but you're collecting a very powerfully rich database that will do that from all these citizen scientists that are joining Zoe and providing these data. It is obviously really exciting to be able to properly test these things. And, you know, as Sarah knows, I was very nervous before we did the randomized control trial on like the Zoe membership, because you basically, there's nowhere to hide, right? Does this really work? If people, you know, do this product, start doing the test, get their results, then follow all of this guidance using, you know, their app and then, you know, retest later, does it genuinely improve their health? So I was very nervous and Sarah and Tim both said, well, we're not going to keep doing this unless we test this. That's what you have to do as a

scientist. So it was very relieving to see that it works. And I think what is exciting is that, you know, we're continuing to use, you know, all the new data to understand how to improve it. And I do think that it's really exciting to see how much just in the data that we're collecting, how much it seems that some of these other factors like, you know, for some people, the time of day when they eat and time restricted eating, you can really see these differences in behavior. So, you know, I think Sarah has convinced me this is pretty exciting. Yeah. And it's just another tool in the toolbox. I think I would really emphasize to people don't focus on a particular tool.

Don't focus just on time-restricted eating or eating rate or, you know, focus, like you said, on a particular food. We've got so many tools in our toolbox. Let's choose the ones that still bring us joy. And let's put the rusty old ones away that either we don't like or aren't helping our body put them away and also choose choose the ones that are going to have the biggest size impact so for example we know that breakfast for those that have breakfast that counts for 20 of our energy we know that snacks accounts for most people 25 of our energy intake these are eating events that we generally do in isolation,

so they're not dependent on someone else around us. These are really simple ways that we can improve our overall diet, just changing our breakfast or just changing our snacks. Right. And this will build on itself. So it's food. You eat food every day. So if you can find some of these changes that, so as you mentioned earlier in our talk today, you can't feel your blood cholesterol, you can't feel your blood glucose on any given moment. But if you have less of a foggy brain, if you have more energy, you're feeling more alert, a lot of those are things that will be impacted by this.

And so as you play with some of these and you see that this modest change led to you being clearer headed, more articulate, that's empowering. And then you go on to the next one and the next one and the next one and it'll build. So it's a very exciting time. And this is what we ask people as well, following the Zoe program and on the method study, we actually ask people how they felt. Now I've run over 30 randomized control clinical trials. I never ask people how they feel. I measure all of these measurements of cholesterol, of glucose. And what was amazing is people felt great. So we know people on the ZOE program feel great,

but actually putting it to the test in a proper randomized control trial, people had more energy, they had better mood, they felt more alert. And I found that really quite empowering because always I've only been interested in these blood markers, but actually seeing that people are feeling better. And so then they're more likely to sustain these changes. Yes. Very exciting. That is a brilliant way, I think, to wrap up because we started with this issue about sustainability and I feel like we've finished with sustainability. I know that, actually, I could leave the room and you'd keep talking for like six hours.

We've only scratched the surface. Sarah's like, oh no, there were 10 other things I want to talk about. I'm afraid we're going to have to stop now. There are many more times we can do this in the future. And I'm going to try and do a summary. And we went into quite a few places. So I'm going to do my best. So I think the first thing

was we started by saying basically the whole concept of dieting is broken because the concept of dieting is something you do for a short period of time and actually that doesn't work what you need to think about is what is the way i'm going to eat for the rest of my life and if i do that amazingly like no matter how old i am i I can profoundly improve my health, which I think is for me the number one message whenever I discuss this with anyone. It's like it's amazing. The latest science says it doesn't matter what you've done before, however old you are, whatever, you can make changes now that is going to improve your health, which I just find is just really motivating to do something. The second thing you talked about, which I hadn't heard before, is unapologetic deliciousness, which is a bit hard to say, but a brilliant idea. It is a mouthful. Which is,

you know, the food needs to be something you want to eat and that you can stick with. You therefore need to avoid restriction. Any diet which says, I'm getting rid of all of these things, and this is going to be really hard, you're not going to be able to sustain. So it needs to be something about adding in a lot of good things into your diet rather than about taking everything away. I think very strong agreement that people need to lower the amount of animal fat that they're eating if they're eating anything like the typical Western diet, be in the US or the UK or France, wherever that might be. And as importantly, we need to reduce the number of sort of poor quality carbohydrates. And so that's anything where you're adding sugar to the food. But also I think the thing that is

less obvious for most people, you know, what you technically call refined grains, this is stuff where it's all been, it's no longer like the original seed or grain, and it's become, you know become white flour in our bread or white rice, which I was brought up to think was really healthy. And that almost everyone agreed you want to have more fiber in your diet in part because of all this new science about how this supports your good bacteria and has these positive impacts. And I think, Christopher, you talked about like, if I was gonna make this really simple, it was almost like two things. So one was whole food and not processed.

And what you're explaining is that the processing does, I think like two bad things. One is it smashes all of this stuff up so that when you're eating like this processed carbohydrate, basically your body turns into blood sugar almost immediately. And that causes all of these problems that we've talked about over the last few days and can lead towards diabetes and whatever. But also the processing tends to strip things out.

And basically you're removing lots of the healthiest bits and therefore whole food is sort of like before you've taken all this stuff away and you keep processing, unfortunately is what we tend to get given a lot of and the other part is plant-based and you're very clear it doesn't mean you have to be vegan or you have to be vegetarian but you're moving towards a diet where unlike really I guess what I grew up with which is like a big piece of meat in the middle and a little bit around the side, suddenly, you know, if the meat is on the plate, it's like a small bit on the side and it doesn't have to be in every meal either. And then I think Sarah was explaining when you think about plant as well,

you really want this diversity of plants because it's giving you all of these different fibers. And Chris, we were talking about one of your studies, you know, that we, and we see this as well, all the different fibers are supporting all the different bacteria. So sort of whole foods and plant-based is your core. And then we talked a little bit about, don't be scared of fats. Many of us were brought up to be scared of fats, but you know, Sarah, again, she'll talk for an hour about how good many healthy fats can be. And it's really, these are these sort of plant-based fats. And you talked about avocados and olives and olive oil and nuts and so long. And then I think towards the end, we talked really about personalization, the idea there

isn't just like one size fits all. You did this brilliant study called Diet Fits, and it turned out you could go to these two extremes of like low fat or low carb. And on each of them, some people would do really well and some people would do really badly. And Sarah, you talked about our own studies showing, well, it sort of makes sense because you can see like a 20 fold difference in how people's blood sugar responds and how people's blood fat responds. So it sort of makes sense that there isn't just one answer for everybody. And I think we wrapped up by saying, you know, I think there is quite a lot of consensus, therefore, about key things that people should change.

There's also a lot of exciting new science coming, which is early about new ways of thinking about eating. And Sarah, I think you mentioned, for example, time-restricted eating, when you eat, sleeping, all of these things potentially having a lot of effect on your health and just starting to be studied. And, you know, probably keep watching here because hopefully there'll be some exciting new studies that we can report back on in the future. Fantastic. Great wrap up. Great. And foods to be enjoyed. That's the most important. And listeners, be kind to yourself. It's a journey. Enjoy the journey.

I think that's a brilliant way to wrap up. Thank you very much, Christopher and Sarah. Thank you. I hope that you learned a lot on today's show about the best and worst diet and about what to eat for your health. Now, if listening to this episode has motivated you to change how you eat to improve your health, then you may want to do what I do, which is use Zoe's app every day for personalized advice and personalized support

on how I can eat the best foods for me. To learn more about how Zoe can help you to feel better now and live healthier in the years to come, simply go to zoe.com slash podcast right now. You can also get 10% off your membership. As always, I'm your host, Jonathan Wolfe. Zoe Science and Nutrition is produced by Yellow Hewins Martin, Richard Willen, and Tilly Fulford.

The Zoe Science and Nutrition podcast is not medical advice. It's for general informational purposes only. See you next time.