What to eat for your health, according to science

Do any diets truly work? People have asked this again and again since ancient times.

We know that food is linked to health. So, if we don’t feel great, we know we should change something about our diets. But with so much conflicting advice, it can be hard to take the first step.

Given all the diet plans, diet bars, diet soups, diet books, diet influencers, and diet gurus, where should we turn? 

Should we completely cut out animal products or everything except animal products? Veganism and the carnivore diet each have avid fans, but they can’t all be right, can they?

In this episode of the ZOE Science & Nutrition podcast, we hear from Stanford Prof. Christopher Gardner and ZOE’s Chief Scientist Dr. Sarah Berry. 

With decades of experience researching links between what we eat and our health, they help us make sense of fad diets — and tell us what we should really be eating to improve our health and happiness.

Episode summary

One of the greatest misconceptions about diets is that you only have to follow them for a short time, then you’re done.

In reality, a healthy diet is a lifelong journey. So, it has to be something you can stick to: a true lifestyle change.

As Sarah often says, “If a food is too healthy to be enjoyed, it’s not healthy at all.”

But the great news is: It’s never too late to benefit from an improved diet. Whatever your age, if you switch from an unhealthy to a healthy eating pattern, you’ll likely see improvements in your cholesterol levels, blood sugar, inflammation, and weight.

A recent study found that switching from an unhealthy to a healthy diet at 40 can add a decade to your life. And switching at 70 still adds around 5 extra years. With this much living at stake, eating well should be everyone’s priority.

Before explaining the best way to eat, let’s ask which diets are the worst for your health.

According to Christopher, the bottom slots go to the most restrictive, animal-based diets: keto, paleo, carnivore, and the Atkins diet.

They’re high in saturated fat, very low in fiber, and almost impossible to stick with in the long term.

If changing your diet is a journey, you have to enjoy it in order to stay on track.

So, what should you do? The overarching message from Christopher and Sarah is: Opt for whole foods and plants. No powders, potions, or incantations. No overpriced pills or sales pitches.

And rather than trying to change everything at once, which fad diets require, start by picking a couple of realistic changes you can make now.

It’s a simple message with powerful effects. Whole plant foods — like a piece of fruit, a handful of nuts, or a can of peas — are rich in fiber.

Fiber nourishes your gut microbiome. And fiber-rich foods also take longer to eat and digest, so you might feel fuller for longer.

At the same time, plants contain a heady cocktail of healthy compounds — including polyphenols. These act as antioxidants and have anti-inflammatory powers. 

Animal products, by contrast, don’t contain fiber or polyphenols. 

Another important difference is fats. Animal products contain saturated fats, which, when eaten regularly, increase the risk of heart disease.

Plants, on the other hand, contain virtually no saturated fat. Even plants with high levels of fat — like nuts and avocados — have healthy mono- and polyunsaturated fats.

Nutrition scientists are still working out the complexities of human nutrition. But we know that none of the popular, celebrity-backed diets will work in the long run. We need long-term changes that favor real foods over snazzy marketing. 

So, while no single diet is perfect for everyone — we’re all different, after all — choosing “whole food, plant-based” as your mantra will keep you on the right track.

And remember, it’s a marathon, not a sprint (though hopefully less exhausting and certainly more delicious). 

“I have a Ph.D. in nutrition science. I'm still changing my diet to this day as I do more studies,” Christopher explains. “You should let yourself experiment. The beauty of food is you get a do-over every day you want.” 

Make small, sustainable changes. Listen to your body and keep experimenting. Go easy on yourself. You might try something that doesn’t work, and that’s fine. If you think of it as a journey, you can enjoy the process and just keep moving.

Show notes

If you want to uncover the right foods for your body, head to zoe.com/podcast, and get 10% off your personalized nutrition program.

Follow ZOE on Instagram.

Find top tips for better gut health from ZOE Science & Nutrition — download our FREE gut guide.

Is there a nutrition topic you’d like us to explore? Email us at podcast@joinzoe.com, and we’ll do our best to cover it. 

Episode transcripts are available here.


Welcome to ZOE Science & Nutrition, where world-leading scientists explain how their research can improve your health.

I’m your host Johnathan Wolf, 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 Gardener 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 Kings 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.

[00:00:00] Jonathan Wolf: Christopher, thank you for joining me and Sarah today. 

[00:00:10] Christopher Gardner:  This should be fun. 

[00:00:11] Sarah Berry: I'm very excited. 

[00:00:13] Jonathan Wolf: Why don't we start with a quick fire round of questions. And I think you remember the drill. 

[00:00:15] Christopher Gardner: I do. 

[00:00:16] Jonathan Wolf: One word. This is a yes, a no. 

[00:00:23] Christopher Gardner: But for one question I get maybe a little bit of an opportunity to expand.

[00:00:28] Jonathan Wolf: If you're very good, you know, it's like the prize for professors for managing to keep the rules at the beginning, then they get a whole sentence at the end.

[00:00:34] Sarah Berry: He doesn't let me have a whole sentence. You're very lucky, Christopher. 

[00:00:39] Jonathan Wolf: So, can I improve my health if I change what I eat? 

[00:00:43] Christopher Gardner: Yes. 

[00:00:44] Jonathan Wolf: Are some popular diets harmful to your health?

[00:00:46] Christopher Gardner: Yes. 

[00:00:47] Jonathan Wolf:Is there one diet that works for everyone? 

[00:00:49] Christopher Gardner: No. 

[00:00:50] Jonathan Wolf:Should men and women eat the same diet? 

[00:00:53] Christopher Gardner: Yes. 

[00:00:54] Jonathan Wolf: Is there one food that can drastically improve my health? 

[00:00:57] Christopher Gardner: No. 

[00:00:58] Jonathan Wolf: See, that was easy. Right? 

[00:01:00] Christopher Gardner: Oh yeah, okay. 

[00:01:03] Jonathan Wolf: That was very easy. So now, you get a whole sentence. What's the biggest myth about healthy eating that you often hear?

[00:01:16] Christopher Gardner: 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. 

[00:01:31] Jonathan Wolf: 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 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. Back to the start, and ask you this, why do people go on diets? 

[00:02:00] Christopher Gardner: Oh, great question. They intuitively know 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.

[00:02:24] Jonathan Wolf: 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?

[00:02:35] Christopher Gardner: 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. 

[00:02:49] Jonathan Wolf: And why is that a myth, Christopher?

[00:02:50] Christopher Gardner: 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. 

[00:03:11] Jonathan Wolf: 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 this saying, well, you know what? I can't do that. So therefore I should just give up. Is it as bad as that? 

[00:03:28] Christopher Gardner: 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.

Yeah, you should be kind to yourself. You should let yourself experiment. I mean, the beauty of food is, 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. 

[00:04:08] Jonathan Wolf: 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? 

[00:04:37] Christopher Gardner: 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.  

[00:04:55] Sarah Berry: 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 U.K. / U.S. 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 you know, I think that's really encouraging that people should really focus on, actually at any time I can still make a huge difference. 

[00:05:34] Christopher Gardner: Yeah. Very encouraging. 

[00:05:36] Jonathan Wolf: It's amazing and incredibly positive, I think. 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, we're discussing this today. 

[00:06:00] Christopher Gardner: Yeah, you have to like it. You have to enjoy it.

[00:06:05] Jonathan Wolf: Which sounds a bit radical, actually. I'm laughing, but that's because I feel yeah. 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 probably 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.

[00:06:34] Christopher Gardner: 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 want to 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, like, 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.

And 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. 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. 

[00:08:35] Sarah Berry: Yeah, I'm a great believer in if a food's too healthy to be enjoyed, it's just not healthy at all. And, you know, 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 U.K., less than 1% of people actually follow any kind of healthy eating guidelines. It's the same in the U.S. 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.

[00:09:39] Christopher Gardner: 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. 

[00:10:43] Sarah Berry: And they didn't really eat it.

[00:10:43] Christopher Gardner: 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.

[00:11:11] Jonathan Wolf: 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'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, um, restriction. And then there was the Mediterranean diet, which suddenly the way that you were selling it to me, Christopher, tasted, you know, 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 you think is best? So maybe start with what are the worst diets for our  health?

[00:13:16] Christopher Gardner: 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.

[00:13:30] Jonathan Wolf: And so, and why is that? Why are they, why do you feel like that's what makes them worse, the restriction and the animal fats? 

[00:13:37] Christopher Gardner: 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 less refined 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. 

[00:13:26] Jonathan Wolf: I think another thing that a lot of people feel is, you know, 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 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, you know, slowly going up.

And so they would like to be able to do something which is going to give them, you know, a fast effect on that. So I think to me, you know, 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.

[00:14:33] Christopher Gardner: 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. 

[00:15:00] Jonathan Wolf: And so you're saying, you know, people listen to this. You can really change how you feel and like, even markers of your health. You know, things that a doctor can measure in your blood, you know, in just a few months without having to go for like, you know, these sort of extreme ketogenic diets or something like that. 

[00:15:19] Christopher Gardner: So, 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.

[00:16:09] Sarah Berry: 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.

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. 

[00:16:40] Jonathan Wolf: 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 gap between the scientific evidence that, you know, both of you talking about right now on topics like calorie counting and sort of low fat food.

And then what we see on, you know, the food labels when we go to the grocery store or official guidelines where basically, you know, I looked again this week, you know, you, you walk in there and like everything still says low fat on it, unless it says high protein. And there are calorie labels everywhere, and yet you sort of demolished both these approaches to thinking about how we should eat.

[00:17:30] Christopher Gardner: 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 think 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 time. It's almost never that simple. Sorry, listeners.

[00:18:30] Sarah Berry: 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. 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.

[00:22:43] Christopher Gardner: The answer is just to get people to think more critically. I mean, to actually, I think this is an 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.

[00:19:50] Jonathan Wolf: 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?

[00:20:25] Christopher Gardner: Okay, and I think Sarah's going to be with me on this one. My first answer is, it depends. 

[00:20:30] Sarah Berry: Absolutely. 

[00:20:33] Christopher Gardner: My next two follow ups are, please tell me with what and instead of what.

[00:20:35] Sarah Berry: Yeah, and where are you now? 

[00:20:38] Christopher Gardner: 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? They 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.

[00:21:30] Sarah Berry: 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. 

[00:21:58] Christopher Gardner: 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. You know, 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 that. 

[00:22:44] Jonathan Wolf: 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? 

[00:22:56] Christopher Gardner: Yeah. And, you know, there's different names and different approaches. If I had to ask, you know, 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, you know, 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.

[00:24:50] Jonathan Wolf: 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 were 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. 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 we can't have it all nicely, sort of, processed and prepared by the food manufacturers? Because we're busy people and we have to have this sort of whole food thing that you just mentioned.

[00:25:46] Christopher Gardner: 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.

[00:25:55] Sarah Berry: Yeah. And it means how full you feel, because I know you would want us to give a simple term for that.

[00:26:00] Christopher Gardner: And so this comes up for me all the time thinking, so one of my favorite authors is Barbara Rowles 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. 

[00:27:23] Sarah Berry: 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 you know, 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. 

[00:28:35] Christopher Gardner: 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. 

[00:28:57] Sarah Berry: Yes 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.

[00:29:06] Christopher Gardner: And it was  hard for that message to get to the brain in time to stop you.

[00:29:10] Jonathan Wolf: 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, you know, don't want to stop eating it, so I'm just going to end up consuming more calories. But there's a 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.

[00:30: 02] Christopher Gardner: I've got a colleague named Michaela Kiernan who approached this in a wonderful way. She said, okay, you know, 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, you know 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 or as convenient. Of course not. Not until you get accustomed to it, and then it will replace that, and it'll work just as well. 

[00:31:12] Jonathan Wolf: 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 two 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, it's 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?

[00:31:49] Christopher Gardner: Sure. Cause the, I mean, the, some of the key things that 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. 

[00:32:16] Jonathan Wolf: And why is the fiber good? 

[00:32:18] Christopher Gardner: 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. It’s satiating, it'll help you feel full sooner, it'll last with you longer. 

[00:32:40] Sarah Berry: This is something we're really interested in as well, because we know that fibre is like the party food for the microbiome as well. And that's where we see the strongest signals. 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 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. 

[00:33:16] Christopher Gardner: 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 looked at 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 fibers. 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 it 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. 

[00:34:14] Sarah Berry: And this is why we talk about diversity so much, because we know that there's no point just focusing in on one fibre or one aspect of, of a food, that we have to make sure we have a diversity of all the different bioactives and all the different kinds of fibres.

[00:34:31] Jonathan Wolf: 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. What does that mean if I'm thinking about what I'm eating? What does that imply?

[00:34:43] Sarah Berry: 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 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 color. So by getting a whole rainbow food, you're getting different polyphenols, but you're also going to get a variety.

[00:35:11] Jonathan Wolf: I'm guessing my red pop tart, coming back to a previous comment, that's probably not the polyphenols that are coloring it. Is that, am I right in guessing this?

[00:35:17 Sarah Berry: 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 or be producing the chemicals that we know have such a wide impact on our health.

[00:35:47] Jonathan Wolf: 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…

And 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 pouring oil over my food, which I do a lot now, but it still feels 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. You know, 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?

[00:36:44] Christopher Gardner: Yeah, so 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 mono and polyunsaturated fats.

[00:37:06] Jonathan Wolf: 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. 

[00:37:11] Christopher Gardner: Yeah, I was listing all foods, plant based foods that have a fair amount of fat in them.

[00:37:20] Sarah Berry: I'm saddened that there's still this perception that, you know, 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?

[00:37:52] Christopher Gardner: Yes because of this low fat stigma, very focused on low fat yogurt which happens to be full in the U.S. of sugar. Like they'll have a fruited yogurt, this is, uh, 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. 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.

[00:38:25] Sarah Berry: 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 fat, 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 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 that makes food taste great, it carries the flavor. It has that creamy mouthfeel as well.

[00:39:24] Jonathan Wolf: And so listening to all of this, you could start to say, okay, so there is one, like, one diet, one way of eating, which is the best for everybody. Like, is that the conclusion?

[00:39:36] Sarah Berry: You're really pushing on  this one, Jonathan. 

[00:39:37] Jonathan Wolf: So tell me about that, and I know, Sarah, you were saying earlier, we have to mention one of Christopher's fantastic studies, you know, exactly around this.

[00:39:45] Christopher Gardner: 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 want it to be a healthy low carb and a healthy low fat. Cause 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.

[00:40:52 Jonathan Wolf: So there were 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.

[00:40:58] Christopher Gardner: 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 an absolute continuum. Somebody lost 60 pounds. Oh, should we do kilos here? No, let's, let's talk pounds, 60 pounds. Somebody lost 55, 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 carbon fat.

[00:41:33] Jonathan Wolf:So what's the answer? 

[00:41:35] Christopher Gardner: 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.

[00:42:07] Jonathan Wolf: So Sarah, what's going on?

[00:42:08] Sarah Berry: 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, it's hugely different. 

And we see this with our ZOE predict research, 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.

[00:43:23] Christopher Gardner: Yeah, 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 scientist 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. 

[00:44:09] Jonathan Wolf: I'm struck just by this conversation is sort of like the logic behind why we do this podcast at all. We want to make the latest scientific information available for free to anyone who wants to listen.

And the reality 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 or not processed, is hard. 

And I think this is one of the reasons that we see the level of success that we do for people following their ZOE program is this ability to get this 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. 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.

[00:45:28] Sarah Berry: So Jonathan's being very kind to me here, Christopher because my 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 this area and we are now focusing and it's now becoming part of our advice, which I'm really proud of. 

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, the 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 that I know you're familiar with 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 the mix as well, I think it's really magical way that we can easily improve our health as well. 

I wonder what your thoughts are on this.

[00:47:35] Christopher Gardner: 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, you have to have the ideas. So you're generating your own hypotheses for the future. I agree. 

This is a fascinating area. It reminds me of, you know, if you're talking time restricted or those kinds of issues, I often give a lecture while I 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 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 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, and providing these data.

[00:49:05] Jonathan Wolf: 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 controlled 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 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 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, this is pretty exciting. 

[00:50:04] Sarah Berry: 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 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 prove our overall. Just changing our breakfast or just changing our snacks, right?

[00:50:55] Christopher Gardner: And this will build on itself. So it's food. You eat food every day. So if you can find some of these changes. So as, 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 clear 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.

[00:51:34] Sarah Berry: 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 controlled 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 programme feel great, but actually putting it to the test in a proper randomised 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. 

[00:52:15] Christopher Gardner: Very exciting.

[00:52:16] Jonathan Wolf: That is a brilliant way, I think, actually 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 the next six hours.

[00:52:28] Sarah Berry:We've only scratched the surface. 

[00:52:29] Jonathan Wolf: Sarah's like, oh no, there were 10 other things I want to talk about. I'm afraid we're going to have to 

[00:52:33] Sarah Berry: No, 100. 

[00:52:34] Jonathan Wolf: 100 other things. 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 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. 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 gonna 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 it in the U.S. or the U. K. 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. So there's this stuff where it's all being, it's no longer like the original seed or grain and it's become, you know, white flour in our bread or white rice, which I was brought up to think was really healthy.

And almost everyone agrees you want to have more fiber in your in your diet In part because of, like, 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 going to 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 know, 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 that 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 Christopher, you were talking about one of your studies, you know, that 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 DIETFITS 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 study 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 sort of 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.

[00:57:35] Christopher Gardner: Fantastic. Great wrap up.

[00:57:37] Sarah Berry: Great. And food's to be enjoyed. That's the most important.

[00:57:41] Christopher Gardner: And listeners, be kind to yourself. It's a journey. Enjoy the journey. 

[00:57:47] Jonathan Wolf: I think that's a brilliant way to wrap up. Thank you very much, Christopher and Sarah.

[00:57:54] Sarah Berry: Thank you. 

[00:57:55] Jonathan Wolf:  I hope that you've learned a lot on today's show about the best and worst diets 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 to 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/podcast right now. You can also get 10% off your membership.

As always, I'm your host, Jonathan Wolfe. ZOE Science & Nutrition is produced by Yella Hewings-Martin, Richard Willan, and Tilly Fulford. The ZOE Science & Nutrition podcast is not medical advice. It's for general informational purposes only.

See you next time.