Your gut health, dementia, and weight loss questions answered by Prof. Tim Spector, Prof. Sarah Berry and Dr. Federica Amati

How quickly can you improve your gut health? Can diet help lower your risk of dementia? And what should you know about food labels and healthy weight loss?

In this special live Q&A, Prof. Tim Spector, Prof. Sarah Berry, and Dr. Federica Amati answer the biggest nutrition questions and share practical, evidence-based advice you can use today.

Drawing on decades of research and data from hundreds of thousands of people, they explain how diet can influence the gut microbiome, brain health, hunger, energy levels, and long-term health.

They discuss dementia risk, healthy snacking, intermittent fasting, ultra-processed foods, plant diversity, breakfast, food labels, and the latest science on weight loss.

If your daily food choices influence your gut health, brain health and future wellbeing, which change is worth making first?

🌱 Try our science-backed and tasty wholefood supplement Daily30

🌿Let your gut microbes snack on the ZOE Gut Health Bar

Get our brand-new app and Gut Health Test designed by world-leading gut health and nutrition scientists to build healthy eating habits 👉 Join ZOE

Follow ZOE on Instagram.

Actionable takeaways

How quickly can my gut microbiome actually change?

Some microbes shift within days, but most meaningful changes take around six weeks to three months. The worse your starting point, the faster and bigger the improvements tend to be.

Are pesticides on fruit and veg something to worry about?

Thick-skinned produce like oranges and avocados are low risk. Berries and oat products tend to carry higher pesticide levels, so it may be worth buying organic if you eat them often. Either way, eating more plants matters more than going organic.

Why do oats raise my blood sugar?

Highly processed instant oats digest fast. Steel-cut oats, soaked overnight and paired with protein or healthy fats like nut butter, are much gentler on blood sugar and keep you fuller for longer.

Is snacking bad for me?

Snacking itself isn't the problem, it's what you reach for. Choose snacks high in fibre and protein to support your heart health and overall health. E.g. nuts, Greek yoghurt with fruit, or roasted chickpeas.

Is intermittent fasting safe for women?

Yes, in reasonable forms like a 12 to 14-hour overnight fast. For post-menopausal women specifically, timing (like not eating late at night) may matter more than the exact length of the fasting window.

What's the best way to start GLP-1 weight loss medications?

Appetite drops by 30–40% on weight loss drugs, so make each bite count. Focus on high-fibre foods to support your health and reduce side effects like nausea. E.g. wholegrains, legumes, oily fish, and Greek yoghurt.

Transcript

Jonathan: Welcome everybody to what is a bit of a milestone for the podcast. This is the first time we've ever done a live podcast recording. This is also the first time we've ever had all three of our ZOE spokespeople together in one show. So we're about to discover whether or not we should have done this ages ago or this is like a disaster and too many opinions all in one room. So I know you're all really excited about the audience Q&A and ready to go, but I thought before we could kick it off, I was gonna ask each of you just one question. Starting with you, Tim. What does ZOE mean to you?

Tim: Is this a yes or no?

Jonathan: No, no. You're even allowed more than a sentence, Tim.

Tim: Well, ZOE means life in Greek, and it certainly changed my life from when I first met you nine years ago now, and it changed me from, you know, a dull academic to a dull entrepreneur and scientist. But it's really allowed me to do what I was doing on a very small scale, talking about gut microbe, but just talking to small rooms of academics, small amounts of people reading my work, to really bring those messages to hundreds of thousands and millions of people in a way that wouldn't have been possible before. And as it's grown and the company has evolved, we're seeing this as a very long-term mission. It's very hard at the beginning of it to see anything long term, 'cause you say, "Are we gonna survive a year?" You know, "Will I strangle Jonathan after the first few meetings?" Because when academics and business people clash, then often there's fireworks. But we got through that honeymoon period, and we can now see this really important future. And I see, you know, this really important role for myself now through, you know, the media stuff I'm doing and the stuff we're doing for ZOE. It's all coming together as a real mission to change the way we all think about food and the importance of food and give us extended healthy life, and that all brings it back to the mission of ZOE. So it's really now very close to my heart, and that's for me what ZOE means. It's bringing the science to so many more people that couldn't have had it before.

Jonathan: That's really lovely. Sarah?

Sarah: I would say for me it's about putting science into action. So I've been, like Tim, an academic scientist for over 25 years. I've run more than 30 randomized controlled trials. And yes, I'd spend years doing these studies, years applying for the funding, years recruiting people, years analyzing the samples, years writing it up, getting it into a manuscript. Did it make a difference? Well, I'm sure none of you have ever read any of those manuscripts. So I think what's real exciting is that we rarely, as academics, ever have the opportunity to communicate our research at the scale that we've been able to through the podcast, but also put into action research findings in the way that we do at ZOE from their own research that we do at ZOE in these hundreds of thousands of people at the scale, depth, breadth, and precision that we could never, ever do in an academic setting. But also to be able to have all of the incredible resources that we have at ZOE that turn scientific information, scientific findings into actionable advice that actually really makes a difference, and I've had the most exciting eight and a half years of my life. It's just been so fun. I don't consider it work, my ZOE journey. I get up and I'm just so excited because the opportunities that we have, it's just so fun as a scientist.

Jonathan: So I love all of that. But I am tempted to ask you to share your initial experience when we first tried to get you involved with ZOE.

Sarah: Do you want the censored or uncensored version?

Jonathan: I think they want the uncensored version.

Sarah: Okay. So I got an email from the esteemed Professor Tim Spector, who actually works in a different department from me. I'm in nutritional sciences, he was in genetic epidemiology. Even though he had already published well-selling nutrition books, he was still just dabbling in nutrition, 'cause God forbid he's not in our department and dares to call himself a nutrition scientist. Sorry, Tim.

Tim: She was one of the nicer ones. Yeah, so imagine what the others were like.

Sarah: That's quite true. Anyway, I had an email from Tim to ask me, would I come to talk to him about my muffins? This is true.

Tim: Everyone likes Sarah's muffins.

Sarah: So what he did realize is that I had a lot more to offer than just my muffin recipe, and so he asked for me to come back and meet you, and George, the other founder. And I remember meeting both of you and going back to one of my colleagues after saying, "Oh my God, I just met these two crazy guys. They think they can pull off 1,000 people postnatal study in nine months." Bearing in mind, the kind of trials we did, we would have probably 20 people over three months doing this. But you know what they say, there's a thin line between genius and madness, and what you did prove to me is that actually it's pure genius, no madness, and that Tim, you have learnt to be a lot less rude, actually. And I do love working with you.

Jonathan: And Federica, what does ZOE mean to you?

Federica: So I think for me, I came from sort of the other side of it. So I was a public health scientist by training, but I was a clinical nutritionist. So I was working one-on-one with people trying to really make an impact on their lives individually. And when I was introduced to Tim before I met ZOE, I was asked if I could help Tim with his Bible, also known as Food for Life, the first one, the big tome. And I was so excited to work on that because it was an opportunity to write a book that thousands of people would read, and it had so much information in it, and it was so applicable. And so when Tim said, "I'm working on this project, it's called ZOE, I think you'd enjoy it," the potential impact that I thought I could help to bring to this company, to ZOE, in reaching millions of people with evidence-based advice that could change their lives at such scale just was so exciting to me. For me, ZOE is impact. That's what it represents.

Jonathan: Imagine a version of you in six months' time, someone who's made a few small changes and feels dramatically better because of it. That is why we make this show, to give you the latest science and the tools to get there. But to keep doing that, we need your support. If you've gotten value from this episode, please hit subscribe. You'll get a front row seat to the latest science, and we'll keep doing all the work to bring it straight to you. Okay, now back to the show. All right. We're gonna move to audience Q&A here. So I've got a question here from Faye Capstick. "How quickly can I make beneficial changes to my gut microbiome by following ZOE's advice?" Maybe we'll get Tim to start with this.

Tim: There was a small study about 10 years ago that looked at a small number of people and sampled their stool sample every day, and they were also looking at what they were eating every day, and they were shifting their diets in certain directions. And they could see changes on a daily basis in the gut microbiome. They were just looking at normal variation. They didn't try and just make it super healthy. So we have to extrapolate from that to our own studies where we've been doing projects where we clearly see changes within a month. And so it's somewhere between a few days and a month, depending on what you're looking at. But I think generally it's really rapid in some microbes, and in others it's gonna take longer.

Jonathan: I've got a second question from Sophie Pelka: "How long does it take for your gut microbiome to change once you've introduced 30 different types of plants a week?"

Tim: Well, again, we know that it depends where you start from. The worse your gut microbiome, the faster and the bigger the changes. If you're already at a really high point in your diet, you're having lots of fiber and ferments and everything else, it's gonna be harder to see that difference. These are really tough questions because all of you guys have really different gut microbiomes. You only share 20% with each other, so everyone's gonna have a slightly personalized response to this. But in general, you'll see changes certainly within three months, even if you're at quite a high level, and probably six weeks.

Jonathan: Would that then be the end of the change, or would you expect that to continue to change at three months, six months, 12 months?

Tim: I expect it to keep going up, but everyone's gonna have a different trajectory. And I think we do see this in people telling me their results. You know, they often see a sort of up and down trajectory, but it generally creeping up. But you might have periods where it is a plateau and it is hard to get. And you've been on that journey yourself, Jonathan, with your fight against the antibiotics, where you've done all you can and there's a six-month period and absolutely nothing's happened, and you feel a bit upset. But, you know, then six months later it does start to climb again, and we don't totally understand why that happens. Maybe it's the seasons or other factors, or there's some other stress. You know, diet isn't the only thing affecting-

Sarah: I think what for me really is evidence for how, you know, increasing your plant diversity, getting to the 30 plants comes from our own randomized control trial that we did of Daily30. And so we put our Daily30 to the test. We gave participants either Daily30 or two other controls, and then we looked after four weeks at how that changed the gut microbiome. And I was even surprised myself how people having two scoops of Daily30 a day had, after four weeks, profound changes in their gut microbiome. But I think what was even more exciting is how quickly you can feel different. So whilst you might not see changes in your microbiome for a week or two and these big changes after a month, we know that people from changing their diet have improvements in mood, energy, hunger, alertness even within two to three days. And I think that should always be a real motivator of how quickly changing your diet can improve how you feel now, as long as your long-term-- as well as your long-term health.

Tim: Yeah. So your brain might be better at picking up the healthy gut than actually the microbiome test, 'cause we've got this high evolutionary system that is really good at detecting what's going on. So listen to your energy levels and your mood.

Jonathan: I've got a question here from Rachel Dixon: Is eating 30 different types of fruit and veg a week enough for good gut health, or does it need to be the right mix just for me? Also, is eating the same 30 types of plants each week bad, or is it okay?

Federica: When we think of 30 plants a week, we want to introduce variety at every opportunity. So actually rather not be the same 30 every week, try to change it with the seasons, try to experiment with new ingredients. 30 plants a week is where the data has taken us so far, but there is a world in which 35, 40, 45 holds even more promise. Certainly that's what we see with fiber intake, that 30 grams a day is great, but when you get 40, 50, 60, even 90 grams a day on one of our podcast guests, right, can still have benefits. So with plants, more is truly more. It's clear that it is one of the key ways to improve your gut health. As Tim said, there are other factors at play, but increasing your plant diversity is an amazing way to improve gut health overall.

Jonathan: All right. I've got another one here from Alan Murray: Buying all fruits and vegetables organic can be expensive. Which fruits and vegetables are most likely to have a high pesticide residue and are worth the extra cost for organic? And on the other hand, are there ones which usually have low pesticide residue?

Tim: Pesticides and herbicides, I think we use those terms interchangeably, but a lot of it is herbicides to stop weeds growing rather than bugs. The main one is glyphosate. It's used extensively on wet crops like oats and rye. Used both to stop weeds growing, but it's also then used to dry the crops out. And so I would say, you know, oat products have the highest levels of these pesticides. So that's the first thing you should always try and get organically because you get excessive levels in sort of all these breakfast cereals if they're not organic. Berries are particularly prone to problems, and they also rot, and so they get sprayed a lot with chemicals. Strawberries in particular always seem to come up in the high lists in both the US and the UK. And most other berries as well. Now, so, you know, I know you shouldn't always put things like raspberries and things under the tap 'cause it rather ruins them. But there's always that weighing up the pros and cons of doing that. And there's many fruits and veg you don't have to worry about. Those with thick skin. Oranges you don't have to worry about, avocados you don't have to worry about. Anything with a really thick skin should be fine. Things with thin skin, the chemicals can get inside. And if you just have it occasionally, I wouldn't worry at all. But if it's part of your regular diet, then do make an extra effort to pay the extra money to get it organic. That would be my view.

Federica: I think it's also worth remembering most of us aren't eating enough plants full stop, so get your amounts of plants up first. Organic frozen berries are actually much more affordable than organic fresh berries and obviously last longer, so that's a good tip. And pick the ones that you can afford organic, but remember the benefits of eating them, whether organic or not, is better than not eating them.

Jonathan: Ooh, there's one about oats, so that's a fantastic transition. From Daniel Bellion here, "I see a lot of debate about oats in the morning. Is it a healthy solution, let's say, three times a week?" And I think we definitely need to go to Sarah on this one.

Sarah: Well, we have an entire podcast on this, so go check that out. Absolutely, I think oats are a fantastic option. I would caveat that though saying the most unprocessed oats, so your steel cut oats that take longer to cook, are the best oats to have. The ones that you get in these sachets that have all sorts of additives, emulsifiers, sugars, chemicals, goodness knows what added, no, I wouldn't consider them healthy. You know, it's just kind of the old-fashioned traditional oats. Look at the back of pack labeling, it will just say oats. And the reason that they're good for you is because they have lots of nutrients, lots of micronutrients. They're very high in different micronutrients. They're also one of the few cereals that are also relatively high in protein. But they're also high in a particular fiber called beta-glucan. And beta-glucan we know once you get to a certain dose which you can if you're having porridge regularly, can significantly reduce your cholesterol levels, but particularly reduce your LDL cholesterol, which is your bad cholesterol. So I would consider them a heart-healthy breakfast as well as healthy because of the other micronutrients fibre that's in them.

Jonathan: Now, I would say I'm someone who doesn't have very good blood sugar control, and I've worn, you know, one of these continuous glucose monitors quite a few times eating oats, including on that podcast, Sarah. And my experience is I've yet to find oats that are cooked over the hob that don't spike me. But I know, Federica, you told me that there is a tip for people who are like, you know, would maybe like to have oats, but for whom, honestly, you know, even the ones you're, you know, pretty much everything that you buy standard that you can find in a supermarket still leading to this really big spike and collapse. Yes. Federica, what did you tell me?

Federica: Soaking your oats overnight is a really fantastic way to have them. It doesn't make the starches more readily available in the same way cooking does. It also increases the availability of some of the micronutrients that Sarah's described. And so overnight oats is a really fantastic way to consume oats. And it means your breakfast is ready in the morning, and you don't have to think about it, which is

Sarah: really good. I think as well, Jonathan, we can consider it as a foundation of the breakfast rather than the standalone breakfast. If you can add in other sources of healthy fats and healthy protein, you're gonna balance out your blood sugar, even if you typically get a spike from it. It'll keep you fuller for longer. You won't be on that rollercoaster. So add nut butters to it or add nuts, seeds, you know, these kind of toppings, and then you're really kind of boosting a foundation that's very good with added plants and diversity as well.

Jonathan: Federica, you just mentioned resistant starch, which conjures up this image of, like, the starch that's really unwilling to be where it is. What does it mean?

Federica: So resistant starch is a type of pseudofibre. It's a type of fibre that basically reaches the furthest part of your colon. It's a slower fermentable fibre, and our guts are starving for this type of fibre. They're also in things like green bananas and other whole grains, and they're especially good sort of to feed our gut microbiome and the gut microbes that produce these helpful metabolites called short-chain fatty acids, and these are incredibly important for our satiety signaling. So Sarah just mentioned porridge is one of these foods that helps to keep you full for quite a long time, especially when it's cooked well, balanced well. And one of the reasons is because the resistant starch fermentation resulting in short-chain fatty acid production stimulates the nutrient-sensing cells in our gut that release hormones like GLP-1 and PYY. And that happens quite a few hours after you eat because it's in the distal part of your colon. So it's a real good way to help you feeling satiated for longer and to feed your gut microbes what they love. And

Tim: a tip to get extra resistant starch is, you know, after you've made your potatoes or your, as Federica prefers, pasta, you put it in the fridge overnight, reheat it, and it's got about 40% more resistant starch in it. So actually it'll have more fibre the next day and it'll fill you up more, and it's more nutritious. So it's really weird that, you know, leftovers can be healthier than the fresh.

Jonathan: So does that mean that you get less of the blood sugar spike- Yes, yes ... as a result of turning it from, like, the normal-

Tim: From sugar to fibre, essentially. That's what it's doing. It's transforming the starch into a form that is... can't be digested in the early part of the colon, and it can only be digested by the microbes further on. So always make more pasta and stick it in the fridge.

Federica: Tim's tip is absolutely right. Cooling your starches increases resistant starch

Jonathan: All right, this is definitely one for you, Sarah. I've got a question here from Jen. "I find it really hard to not snack in the afternoon. What can I do to get me through to dinnertime?" Which pretty much describes me every day. What can you tell us, Sarah?

Sarah: Snacking itself is not bad for you. It's about what you snack on. We know in the UK, in the US, in many countries, we get between 20 to 25%, so a quarter of our calories from snacks. That's huge. And I think rather than demonizing snacking, we should be embracing it if we are a snacker as a really simple single dietary strategy to improve our health. I've run a randomized control trial where the only thing I changed in individuals was their snacks. I said, "Keep everything else the same." After just six weeks, people improved their blood lipids, so their cholesterol, their blood vessel function, to such an extent, it equated to a 30% reduction in cardiovascular disease risk just from changing their snacks, and that shows the power of snacking. The problem is, is in the UK, many of us snack on the wrong foods. We know again from our own ZOE Predict research that about 40% of people that put in loads of effort over their main meals undo it all by eating really poor quality snacks. And we do have a problem that there aren't enough prepackaged snacks out there. But something I'm incredibly excited about is that we at ZOE will be launching our own snack bar that we have all created that is, I think, the answer to snacking in the UK. And what's real exciting is we've really taken a different approach to snacking. Why no one else has done this before, I do not know. It's a snack bar that's packed full of healthy protein. It's quite high in healthy protein. It's packed full of fiber. It's got a whopping eight grams of fiber. So if you're snacking two times a day, having two bars a day, which is what's typical in the UK, two snacks a day, you're gonna be getting nearly 20 grams of fiber. And it's a diversity of fiber 'cause each bar has 12 to 13 different types of plants. The other thing that's really exciting about this snack bar is that we've created it to make sure that the matrix or the structure of the plants that are in it are intact. And we know that's important because we know it impacts how quickly you digest it, where you digest it, and what's left over for your gut microbes to absorb. And then lastly, the icing on the cake is we've made the texture be quite chewy, so it's hard to guzzle it down. You know, we live in this broken food landscape where so much of the food is soft textured, so you eat it so fast. And you'll have eaten two snack bars before you've even registered that something's got to your tummy. And so intentionally, we've produced a bar that is hard in texture, that you slow down how much you eat. And we know again from our own ZOE PREDICT research that this means that you have better metabolic health. You consume less calories later in the day. So it's just the perfect, perfect food snack bar.

Jonathan: A lot of food that we eat is designed to be pre-digested or pre-chewed. Maybe Tim, could you talk for a minute about, like, why is that?

Tim: Yeah. It's the way the food industry has been designing food, you know, since about the late 1960s. '70s has been slowly building up this portfolio of foods, and they've realized that it's much easier to work with foods if you strip them of the outside shell of the plant. So you get rid of the kernel, the fibrous bits that contain nutrition 'cause they're hard to manipulate, and they also make it more like it's gonna go off. So that's the reason white rice is there because white rice doesn't go off, whereas brown rice will go rotten if left in a mill. So that's what our ancestors worked out. Same with flour. And, you know, brown flour and white flour, you clean it out of all the other stuff, and then it will last much longer. And also, they're able to manipulate all these plants, just taking the inside bits of it out, getting rid of anything hard, and so they can heat it up. They can pressurize it. They can, you know, make it look like a potato in a Pringles or a Dorito, you know, even if it's made of rice. And they also realized that some people just like eating baby food all their life. You know, we're-- evolutionary idea is that, you know, you go from mother's milk, and there's a little bit of weaning and a bit of squashed banana, and some people stay in that state for sixty years. Many people aren't chewing at all anything. And, you know, that's why you go to fast food places, and those burgers' buns are incredibly soft. You know, you don't really need teeth to eat them. And we're in this state. So it's partly that they've adapted to this very sort of infantile way of eating, but also it's incredibly cost-effective for these industries to make foods like this. And they also know that the softer it is, the faster you can eat it, the more you overcome your normal fullness, and you'll keep eating much more of it, and they'll sell more of this stuff. And they don't mind you just get fat. You know, that's all good for business.

Jonathan: So the pre-chewed basically means you're just gonna sort of wolf it down. You won't even realize you're full, and you're sort of onto the second bar before your brain has even realized the first one is-

Tim: Yeah. We've all been there. You know, the big bag of potato chips or whatever it is, and you just don't even notice you're eating it.

Federica: I think critically by stripping out the fibers that Tim's talking about, we aren't activating these satiety signals as well. So you're eating quite a lot of energy. These are energy dense foods with quite a lot of calories in them. You might get a little bit of satiety from the stretch receptors in your stomach. They sense something is there. But because it's smushy, it's absorbed so quickly in the small intestine so high up. But then there's nothing happening after that to say that there's still food going through and it's nutritious. So by making it so nutrient lacking and low in fibre, you can eat quite quickly, eat a lot of it, but actually still feel hungry half an hour later. This is excellent for profit, because to Tim's point, we have this enormous amount of food available in terms of calories per person. It's about 4,000 calories a day per person available in the food system. But they're not satiating calories, so it means that we're buying more, and they're able to market more products, and we still continue to eat more and more. But it's not helping us in terms of satiety or nutritional status or fiber.

Tim: I think Sarah did a study about chewing.

Federica: The lovely spit studies.

Tim: Yeah.

Sarah: Oh, my chew and spit studies. Yeah, so we've done studies where we've looked at feeding people identical foods, where you just change the structure of the food, so you just change the texture in the way that Tim's talking about how the food industry change the texture. But where you'll give people, for example, large porridge versus finely ground porridge. Back-of-pack labeling's the same, nutrients are the same, ingredients are the same. All you've done is change both the texture and the structure of the food. It changes, obviously, how much you chew it, but it changes actually how your body metabolizes and processes it. It changes, to Federica's point, where you absorb it. The larger, more intact plants are absorbed lower down your gastrointestinal tract that are packed full of these GLP-1 fullness receptors. When the food industry are finely grinding, breaking up everything, softer texture, it's all absorbed higher up. You don't, therefore, like Federica said, get that kind of fullness. We also know that how much you chew your food also determines how full you feel as well. And if the food is already mush, you're not chewing it.

Jonathan: Both you and Federica got very excited about the idea that the bar was something you had to chew. Is this why that was such a big deal for you both?

Sarah: Yeah, so by chewing it, that itself will feed back some sort of satiety fullness signal, but more importantly, will slow down how fast you eat the food by having that harder texture. And that's real important because we know if you look at two foods, one that could be minimally processed and one that is processed, even if they're similar foods, you get about a 50% difference in the rate at which you eat it. That results in at least a 50% difference in how full you feel from the food, but also a difference in how many calories you go on to consume after. There's a wonderful phrase that one of my colleagues who works in food texture, his entire career is about food texture, that he often says, which is very practical based, "Put the crunch back into your lunch." It's a simple strategy, and there's studies to show you could have a soft burger, soft patty, soft bun, soft lettuce, or you could just crisp it all up. Just by putting the crunch back into it, means you're chewing it more, means you're slowing down. And what the studies show is you will consume less of that food, and you'll have a better metabolic response.

Tim: Is this why you like crisp sandwiches?

Sarah: I love my crisp sandwiches.

Jonathan: All right, I'm gonna move us on before there's any fighting in that corner of the couch. So we are going to talk about brain health and mental health because we've had lots of questions around this. And I know that, Tim, this is something that you've been very excited about over the last year, and we have some exciting upcoming books. So let me start with the first question from Andrea Fridas. What evidence supports the link between gut health and mental health, and how strong is the current research on this?

Tim: I think it's a really serious topic because every person with a brain disorder, I prefer to call them brain disorders than separate mental health from degenerative brain health. It's all the same organ. And really there isn't really separation between mind and body. It's just another organ that's going wrong. In every condition studied, there's an abnormality in the gut microbiome when you compare cases with the disease and controls without it. So everything that goes from dementia, Alzheimer's, Parkinson's disease, all the way through to autism, to schizophrenia, to depression, anxiety, PTSD, obsessional disorders, everything. Something's going on in the gut microbiome. Now, that's association. It doesn't necessarily mean it's causation, and it's quite hard to do those studies 'cause you'd have to test someone and then wait ten years in a cohort to do that, and the field is too young. So we have to rely on mouse studies to really show us what's going on. I don't do mouse experiments, but I have to read about them. And these mouse studies are really good at showing mechanisms are possible. Obviously, humans are not mice, but really clever experiments have taken transplants from one mouse to another. You take an anxious mouse, you take their poo, you transplant it into a germ-free sterile mouse, you can make that mouse anxious. And by using antibiotics and things, you can reverse that process. There are also some experiments where they put stool samples from humans with depression or anxiety, and they've transplanted sterile mice with them, and they've reproduced those symptoms. And they've also done that for other mental health disorders like psychosis and schizophrenia. So there really is pretty good evidence there is a link between the two. There are also really interesting links in brain diseases like Parkinson's, which is, you know, a shaking palsy, but it's associated with dementia, and that's really increasing at the moment. And when they look back at their history, they find that ten years before, the majority of people who developed these brain symptoms had really bad constipation and gut problems. And they're finding that the gut microbiome in those people was abnormal 10 years before and had proteins that were being formed because there was inflammation in the gut microbiome. And we think the link is not the microbes themselves, but it's actually this whole concept of inflammation because microbes are controlling our immune system. Something goes wrong, the immune system goes out of control, you get extra inflammation, and that's why this applies to all brain diseases, not just one or two. This is very much a holistic problem, and that's why we're facing this epidemic in this country.

Jonathan: For you, it's really clear the links between gut health and brain health are really strong, and there's a lot of increasing data that shows that from, you know, experiments with mice on one end, but these examples you're talking about people developing constipation and gut problems like 10 years before they develop a brain disease. And the second thing I heard you say, which is really striking, is that this divide between mental health problems like depression and anxiety and what I guess I would have thought of as brain health problems like dementia for you isn't really real. These are all just one group of things sort of going wrong with your brain, and inflammation for you is maybe this key explanation for the link between, like, the food and your gut health and what is happening in your brain.

Tim: Yeah, that's right. You know, psychiatrists have divided the brain disorders into three hundred and sixty different conditions, and all of them have no diagnostic test. They're just a group of symptoms that every, you know, five or 10 years, psychiatrists agree this goes together with this. But they all overlap. They all have the same risk factors. They all end up having multiple symptoms overlapping by, you know, after a period of twenty years. And the genes, I used to be big into genetics, the genes risk of all these are all the same. There's no big difference. It looks like it's just one disease that's just presenting differently at different times in life, maybe, you know, at different exposures. So I think we need to step back and take a much more holistic view of mental health and realise that, you know, the one thing we've been overlooking and psychiatrists have never really talked about is how important the gut is and how important our diet is and why we've got the biggest nerve in our body runs from our gut to our brain, and eighty percent of the traffic is from the intestine to the brain, not the other way around. Whereas the rest of the body, the nerves all run most of the signals from the brain to the rest of the body, whereas the gut is the opposite. So the gut could be seen to be directing the brain. So I think once you sort of change this paradigm, we can start to really get to grips with it, and people see the link between mood and food. You know, that's what we saw in these-- our trials. In all the ZOE studies we do, whether it's of Daily30, of the, you know, the method study, fermented foods, first thing that changes the brain symptoms.

Jonathan: I've got a question here from Dr. Saz Guscott. The fermented foods data on inflammation is striking. Given how tightly we now link inflammation to depression, do you think that fermented foods are one of the more underrated mental health interventions? Would either of you like to take that?

Tim: Well, short answer is yes. Fermented foods probably work in a different method by a different mechanism, so they're acting synergistically together. Yeah, exactly. So just 'cause you're having fermented foods alone, you know, will help particularly inflammation. But, you know, we don't know, but it's highly likely that adding 30 plants on top of that is also gonna help, and no one's yet done that study.

Jonathan: Amanda Howe says, "My family doesn't believe me when I suggest that nutrition and lifestyle changes can significantly impact their future risk of dementia. Am I right? And what would you say to convince them in no more than two sentences?"

Sarah: Tough one, Tim.

Jonathan: I've never seen you stop, lost for words.

Tim: Trying to think of two sentences. Yeah. That's why it's tough. There's a whole wealth of information. There isn't one blockbuster study that does it, but there's clear data showing that all things associated with poor diet are associated with increased risk of dementia. We know that mouse brains don't develop without a healthy gut microbiome, so we know there's a link between the brain function and this. We know that bad foods are associated with it, and there's unlimited observational epidemiology studies making this link. There's also one of the biggest risk factors for dementia is type 2 diabetes. The main risk factor for type 2 diabetes is poor diet and poor gut microbiome. So that, you know, I would just say ask any epidemiologist and so they'll say there's overwhelming evidence.

Federica: 80% of dementia is preventable with lifestyle and nutrition intervention.

Jonathan: 80%. Amanda, hopefully that's good enough for your family.

Tim: Good luck.

Jonathan: All right. I'd like to switch topic here. We had a number of questions here about weight loss drugs from Dominic H. What would your number one piece of advice to people starting out on weight loss drugs be? And I think that's definitely for you, Federica.

Federica: Great question. My number one piece of advice would be to actually start the dietary change before you start the drugs. The most common side effects of these drugs are gastrointestinal side effects, diarrhea, nausea, constipation, reflux. If you set your gut up for success before you start these drugs, the likelihood of suffering these side effects is lower, and the likelihood that you'll have efficacy at a lower dose is higher. So prepare before you start, and then during treatment, nutrient density, every bite of food counts.

Jonathan: And I've got a follow-up question also about GLP-1s, from Claire Lane: What effect do GLP-1 agonists have on the gut microbiome? Does it make it less diverse as people taking them are tending to eat less well whilst taking them?

Federica: We don't have loads of data on this. It'd be good to have more, but the data we do have shows that there are gut microbiome changes with GLP-1 medication. They're associated with the slowing of the gut transit, so gut motility slows right down, and that in itself changes the environment the gut microbes are reproducing in and living in. Diet absolutely changes as well. So depending on how your diet changes in this time, you can either see an improvement in the gut microbiome, or if you're just eating bad food but less of it, then obviously we see negative changes. These drugs absolutely interact with the gut microbiome. We're just starting to understand how we can preserve gut microbiome health, gut health, but also how the actions of the gut microbes you have can actually amplify and better the effects of the drug. And that's, I think, where the really exciting science is coming out on that, how we can help our gut microbiome make these drugs more effective and more tolerable.

Jonathan: Is it possible to use these GLP-1 drugs and actually improve your diet, or actually is that sort of an illusion?

Federica: These drugs offer an opportunity to improve your diet in a way that will improve your gut microbiome composition, improve your health. If you are able to prepare for the drugs and improve your diet significantly during treatment, the long-term effects and the beneficial effects on your gut microbiome are real. But if you don't do anything, if you just take the drugs and think this is a silver bullet, then the likelihood is it will go the opposite way, and you'll be squandering an opportunity to improve your health.

Tim: I'd go even further. I'd say it's a real disgrace that the government who is saying they're trying to roll this out to people are spending taxpayers' money on this really expensive drug without giving people clear mechanisms to change their food behavior. This is an incredible opportunity that the NHS is squandering. Most people will take the drug, they'll lose weight, they'll stop taking the drug, they'll put the weight back on, they'll go back to their old ways. And it really is a national disgrace if we can't use this long term, and we need tools like the ZOE app, which cost a trivial fraction of the cost of the drug to be given in conjunction.

Jonathan: I've got a question here from Becky Tucker. Tim, if you were given responsibility for improving the country's health over the next 10 years, what are the three biggest changes you would make to the food environment rather than to individuals' behavior?

Tim: Great question, and there's a reason I'm not a politician. First one would be to have strict rules about what food should be served in government-run institutions. Something that's very easy to do. You just say in schools, in universities, in public places, hospitals, that we don't want any of the medium and high-risk ultra-processed foods. That'd be number one. Very easy to do. We've got our new ZOE classification, makes it really clear. That would cut out 25% of the foods that are causing the most damage to our population. I would ban at the same time, you know, vending machines and things like this that are also making our health staff really unhealthy. My second one would be to pass a rule saying that any clearly unhealthy ultra-processed food is not allowed to have health claims on the packet to fool consumers, particularly parents of children that are being targeted with these high in protein, low calorie, low fat, high in vitamins, all this nonsense for really unhealthy rubbish.

Jonathan: And Tim, is that a big issue?

Tim: It's a huge issue. Most people are completely fooled when they go into supermarkets about what to buy, and they're trying to do the best for their family. They think they're doing it 'cause they see nice pretty pictures or cartoons or people of happy, you know, farmers, getting these products, and it's all a lie. And other countries have taken these steps. So they'll be the first two things, you know, I would do. But well, third would be to teach about food and health at school. And we've dropped that now. It should be taught as a primary subject, just like reading and writing. Everyone needs to know how to cook a few simple meals and understand food. If you don't understand it, it's gonna be a huge loss for the rest of your life. Many people are not being told how to cook, only to microwave.

Jonathan: I've got a question here from Michael Burnham. The team's visibility across the media is impressive. The message around the negative impact on UPF is cutting through. However, there seems to be very little evidence that the UK government is moving to address this issue. What else can be done? And I think it'd be interesting also to talk about the situation, not just here in the UK, but more broadly. Let's start with Sarah.

Sarah: I think that absolutely enough is not being done. I do believe that there are efforts that are being made to use processing in a way that can improve health rather than damage health. But I think it's too little, too late in the journey. And I think we're in disastrous times when it comes to the food that we have, because it's not just about what's on our shelves, it's about what we have become accustomed to. So we have become accustomed to cooking foods that take two minutes in a microwave. And, you know, this feeds into what Tim said as his third point. We're bringing up children that aren't educated to be able to cook. And I think that it's not just about therefore, you know, putting taxes on all UPF foods. We have to think of the bigger picture. And there is a big problem as well, Jonathan, that ultra-processed foods are fifty percent cheaper than equivalent minimally processed food. And so there's a very difficult task that the government has that we don't widen disparities. And so because of that, we're stalling. And I think the other thing that's a big problem is in the scientific community as well, there's a lot of discourse around ultra-processed food. What is it about it that's bad for us? And because of that, again, we're stalling. We're never gonna know exactly what additive, emulsifier, cocktail mix is bad for us. We need to embrace the fact that there is too much heavily processed, unhealthy food, and we need to act fast. But there's too many excuses happening.

Tim: Internationally, it's important to recognise that at least twelve, and probably maybe double that number of countries, have now produced national guidelines to say that ultra-processed food, however they define it, is unhealthy and should be avoided. And the UK is not one of them. And the UK has resisted this through its nutrition committee, which sits supposedly independent and says there just isn't enough evidence to say that ultra-processed food is bad for us. But all these other countries disagree and are moving forward with legislation to do it.

Federica: It's worse than that. The government recently announced that they might lower the price of biscuits and other ultra-processed foods to help families. I think we need to really think about subsidising healthy food and making whole foods much cheaper than these ultra-processed foods so that they become the obvious choice. That's what got to be one of the levers that we have to look at.

Jonathan: Great transition to my next question, which is from Karen Boyd. The American food guidelines have changed recently, so the pyramid is now the other way up. Will the UK follow suit?

Tim: United States Department of Agriculture have these guidelines that they change every ten years, and most countries follow their guidelines because they're, you know, they're thought to be, you know, the ones that sort of lead the world in this. And 10 years ago, they're actually quite similar to the current UK guidelines in that they mainly demonize fats. You know, they're sort of favoring starchy foods. They do say, "Don't have lots of sugary drinks." They say, "Eat more fruits and vegetables, have a bit of fish." And they were sort of a bit on the fence on protein. They didn't mention ultra-processed food at all, didn't mention gut health at all. Now, the new guidelines, they mention fermented foods being good. They mention that the microbiome is really important for the first time ever. They mention that ultra-processed foods are bad and shouldn't be given to children, including any sugary drinks under the age of four, or even artificial sweeteners under the age of four, which is something the UK says is fine. And where they went a bit weird is they then said, you know, "But you should have even more meat and butter." Already the average American has twice as much meat as the average European, and they're saying, "No, that's not enough. You need to have these protein levels that are right up here, but you've also gotta do this other stuff and have a ton of vegetables."

Jonathan: Do you think they should be eating more red meat?

Tim: No. They don't need to be eating twice as much as the Europeans, let alone four times as much. At that level, particularly when most of it is processed and poor quality, it's gonna increase the cancer rates. It's gonna increase heart disease rates. And the more meat you've got on the plate, how can you squeeze your 30 plants? It's very hard. There's no room, especially with those big American steaks. By the time you finish that, even your salad seems very hard work.

Jonathan: Actually, I think that's a great transition to the next question from Sonia Castro, 'cause it's about intermittent fasting, which is definitely new science. Is intermittent fasting suitable for women, especially those who are post-menopausal?

Tim: This question comes up a lot because I think on social media, women are singled out and said, "This is highly dangerous and it's not safe for women. It's only safe for men," and this big disparity. When you look at the studies that have been done, they're virtually all in men, and they're virtually all in young men. The one exception to that is the ZOE Big IF study. 150,000 or so people did, and I think 65, 70% were women. So it's the largest group of women doing intermittent fasting, and we found that actually, two-thirds of people, regardless of being male or female, really benefited from it. They got better mood, better energy, they had less bloating, and they enjoyed it. A third didn't. It is personalized, but there's absolutely no evidence that it's harmful, as long as it's not extreme. And I think what we're talking about is really quite modest ones of 12 to 14 hours without eating, which is not the same as going three days without eating.

Federica: I would say it really depends. A lot of women who do try intermittent fasting sometimes take it to the extremes, as Tim said. And actually, what we do know is that because women are often subjected to diet culture, a further way to restrict your diet is probably not going to help you. An overnight fast makes sense physiologically, so just not eating at nighttime is a good idea. But don't make this into another rule where it leads to further restriction, because I think that's where harm can happen.

Tim: Or anxiety or stress-

Federica: Yeah

Tim: ... or mental angst.

Sarah: Can I actually add something to this? You know, given that at ZOE we have run one of the world's largest studies actually in peri- and post-menopausal women, and what we know is that peri- and post-menopausal women metabolize their food differently. We know that they have different perceptions of hunger. And so I think from a very practical point of view in terms of the question that's been asked around intermittent fasting is that actually it's not so much probably the duration of the fast that matters here, it's about the timing of the fast. What we know is that if you consume calories later in the evening, you wake up more hungry the next day. You have worse metabolic responses the next day. And given that our own research shows that post-menopausal women already have more exaggerated responses, already are more hungry, already more prone to put weight on in the wrong places, maybe focus not so much on thinking, "Oh my God, have I eaten in a 10-hour window?" But think about focusing on, "Okay, let's try and not eat after 8:00 tonight or 10:00 tonight."

Jonathan: All right. I think we've got time for one final question from the audience. And Sarah Rodriguez asks, "In a perfect world, what is the best food to eat to break your fast?"

Sarah: So I'd like to use myself as an example. Before I started my journey with ZOE, despite being a nutrition scientist for 20 years by then, I did start my breakfast with pain au chocolats, croissants, and boy, I'd be hungry and hangry a few hours later. And then having met Tim and heard all about his breakfast and gave it a go, and I tell you what, I feel full for four hours, which for me is perfect, but the quality of the foods I'm getting are fantastic. And most of you will probably, if you've followed Tim, will know what his breakfast is. So it's a mix of kefir, so you've got all those wonderful happy bugs dancing around in your bowl. Greek yogurt, so you've got a whacking amount of healthy protein as well. And then whatever mixture of nuts, seeds, berries, et cetera, you want to put in. I add a bit of nut butter as well. Keeps me full. I'm getting plant diversity. Obviously, I add my Daily30 scoop on top as well.

Federica: It's nice to have a favorite breakfast, but I actually change it. So in the winter, I love a porridge, but in the summer, I absolutely love overnight oats, avocado on toast. I love crispy eggs, extra virgin olive oil, make it hot, then crisp them. Delicious. They're so good. My girls love them, too. So it's nice to change your breakfast up, but what Sarah's described there is a really good combination of healthy fats, healthy proteins, a variety of fibers and plants, flavor, and enough food to keep you satiated. Because we actually also know from our own research that having a really satiating and nutritious meal when you break, whenever you break your fast, if you're Tim, it might be 11:00, 12:00. If you're me or Sarah, it might be earlier in the day. It helps you to sustain energy levels and have better nutritional choices later in the day. So begin with breakfast is one of our principles, because if you have a very good breakfast, it actually does set you up well for the rest of the day.

Jonathan: We don't have time for any more Q&A from the audience, but just to wrap up, I'd like to get one quick answer from each of you, if that's all right, about what you're most excited about for the next 12 months. And we had a number of questions from our audience around this, and maybe let me start with you, Federica.

Federica: Okay. So I'm really excited about what we're learning of how we can better understand the messages that happen within our bodies. So whether these are the appetite-regulating hormones that are so popular now, but also what Tim described, how the vagus nerve communicates with our brain. So there's some really exciting science emerging on how things like vagus nerve stimulation and mitigating our stress can actually impact our nutritional health, because our body is one, and how stressed we are or how well we modify these things actually affects how we absorb nutrients from our food. So I'm really excited about that from a science point of view, as well as really excited to see how the gut microbiome science that we've been able to contribute to is helping to shape the future of medicine, whether it's through colorectal cancer, early colorectal cancer research that Sarah's involved in, and some of the Type 2 diabetes research that we've been able to unpick. So those two for me as a scientist and as a clinician, I'm like, "This is so exciting."

Jonathan: Sarah?

Sarah: I am most excited about the gut health bar coming out, and about the fact that we, staying true to ZOE values, are gonna put it to the test. And so my science team, our science team are going to be running a randomized controlled trial, which will be publicly available for everyone to see the results, so we're taking a big chance. But actually, I don't believe we are. My hypothesis is that we will see people consuming our gut health bar versus a standard breakfast bar. We will see significant improvements in how people feel, their gut health, their microbiome, et cetera. And I'm willing to bet something on it. You name it, I'll bet it.

Federica: Dinner on you, Sarah.

Sarah: Dinner on me. If we don't see these improvements, and this is how confident I am... I will take you all out for dinner.

Jonathan: Wow.

Sarah: Not to McDonald's, though. Don't tell Claridge's we're coming.

Jonathan: Last but not least, Tim.

Tim: Well, it's probably not a big surprise to them. I think the next year is gonna be the year of the brain, and how we can tell more and more people about the gut-brain connection, how we can, you know, people outside this room who aren't aficionados can start to see the links themselves between the terrible food environment and their poor mental health and the rise in dementia. And, you know, I think all our studies are now really gearing up to be looking at these factors much more. Every time we do a ZOE study, we're gonna be looking at mood and energy and all these brain things first. Track these in the app, like we used to in the COVID studies when people were looking at their mood, so people can track their mental health just like they track their blood pressure and everything else. And I think people will see these changes, and hopefully this will lead to a real revolution in how we see food and see this is the real antidote to the epidemic of brain diseases that we're having at the moment. And, you know, we can start to spread the word. And the microbiome stuff hopefully will also give us clues because we've now got this database of, you know, over a third of a million people, of which a fifth have got some depression, and we can actually highlight microbes that we can target in the future with prebiotics and probiotics. So yeah, I'm super excited that, you know, we can tackle the hardest problem of all, which is getting our brains healthier, and we all need them.

Sarah: Jonathan, you're always the host, so you never get asked the questions, but I think it would be great to hear from you your ZOE journey or what you're most excited about the next 12 months.

Jonathan: Oh, that was mean. I wasn't expecting that. I actually think it came up in one of the audience questions. I think the thing that I'm most excited about is that we are finally starting to have an impact on the conversation about the central role of gut health and, on the other hand, how we're really fighting this ultra-processed food, and that it is just so bad for us. And when I first got involved in ZOE, you know, we were talking about personalizing advice, we were definitely talking about gut health. We didn't talk about the ultra-processed food at all. And I think I was very excited by the ability to use all of this data, a very large scale. That was my background, to give this personalized advice. And over time, I think, and I think Tim has felt the same way, I've just got angrier and angrier as I understand the reality of the food that surround us and just how terrible it is. And like you can't even know, right? It has these labels that tell you this stuff is great for you. It's high in protein, it's good for your family, and then you realise, like, I've been feeding my children terrible stuff. I've been feeding myself terrible stuff. I optimistically believe that we are starting to change that conversation. So I am really hopeful that in a year we will have more positive things to say about how actually industry is being forced to make changes because of the demands from not just people in this room, but people listening to the podcast, people involved with ZOE all over the world, and that that actually can have this really amazing impact on people's health. So I think that is what I am most optimistically hoping for in an environment where there seems like loads of terrifying things like AI and wars and all the rest of it. This excites me. Well, thank you for turning it back on me, which you're not supposed to do, Sarah. That brings us to the end of our first ever live podcast. I thought it was a lot of fun. It was brilliant to have the audience actually reacting. Thank you so much for supporting ZOE, many of you from the very early days. Thank you for being in the audience and listening to us. And that brings us to the end. Thank you very much.