ZOE Science & Nutrition - How snacking impacts your health

Starting point is 00:00:00 Welcome to Zoe, Science and Nutrition, where world-leading scientists explain how their research can improve your health. Do you often find yourself staring into your fridge looking for a little something? Snacking. How can anything that feels that good really be bad? But those meals between meals that satisfy your hunger are often blamed for excessive weight gain. After all, step one in any old school diet is quit snacking and have more self-control, right? So is that because of the type of snacks we reach for when we need a quick food fix? Is it down to when we snack? In fact, could some snacking actually be good for us? In today's episode, we'll find out what today's science says.

Starting point is 00:00:55 With the help of two world-leading nutrition experts, we're going to feast on the truth behind snacking. Dr. Sarah Berry is a world-leading nutritional scientist who is running groundbreaking research on how snacking relates to health outcomes here at Zoe. My second guest, Tim Spector, is one of the world's top 100 most cited scientists and my Zoe co-founder. All right. Well, Sarah and Tim, thank you for joining me today.

Starting point is 00:01:22 Pleasure. Great to be here. Good to be here in person. Very exciting. So this is the very first podcast that we've done in real life. And I didn't actually realize you could do podcasts in real life. So we've been sort of upgraded and we're going to try not to mess it up too much. Why are you looking at Sarah? So you can see we're really not used to this.

Starting point is 00:01:42 So Sarah's like, am I supposed to say something now? And it's like, no. We're say something now? That is like, no. We're all looking at Sarah to mess it up. I was going to say how lucky I am to spend a few hours with both of you. But then I didn't want to make Tim's head any bigger. So I think although we are in person, I think we should stick to the normal flow of these. And of course, we always start with a quick fire round of questions from our listeners. And just to remind everybody, the rules are you can say yes, a no, or maybe. And what I'd like to do is reach them for a change, have Sarah answer and then Tim answer afterwards, because

Starting point is 00:02:16 I think this is a topic that we may have some fun with today. Are you ready to go? All set. Absolutely. Brilliant. All right. Are most people eating the wrong snacks? Yes. Oh, yes. Tim, we've agreed on something. We can go home now.

Starting point is 00:02:34 I snack every day. Is it bad for my health? Maybe. Maybe. And this is something my mum always told me. Is it true that snacking spoils your appetite? Maybe. And this is something my mum always told me. Is it true that snacking spoils your appetite? Maybe. I'd say yes.

Starting point is 00:02:51 Okay. What's worse, a mid-morning snack or a mid-afternoon snack? Well, I can't answer that with a yes or no, can I? So that's not very fair. I've messed up. You're allowed to answer the mid-morning or mid-afternoon, Sarah. Mid-afternoon. No idea.

Starting point is 00:03:06 Okay. Pass. Can snacking lead to inflammation? Yes. Yes. And finally, and you're allowed a whole sentence on this, what's your favorite snack? Oh, crisps in the day, chocolate at night. Cashew nuts.

Starting point is 00:03:24 All right, we'll come back to that later. So I think as always, it's good just already to start at the beginning. And we had so many questions about snacking from our community. And we thought actually it'd be fun to do our own little survey because we believe a lot in data at Zoe. So we asked our community whether they thought snacking was healthy. And we had thousands of responses. And actually, it looks like there was almost a complete three-way split. So 36% of people said that, yes, snacking is healthy. 32% said no.

Starting point is 00:03:55 And interestingly, 31% said they didn't know. Okay. So it's clearly a very controversial topic. And I think it'd be a lot of fun to sort of unpack that today. But before we start to get to the question of, you know, is it good or bad, can we actually just sort of start at the beginning? And, you know, Sarah, as a nutritional scientist, what is a snack? So there's actually no clear definition of a snack that's agreed amongst the nutrition

Starting point is 00:04:19 community. So we can think of it either as an eating event between a main meal. So any eating event between your breakfast and lunch, your lunch and dinner, as an eating event between a main meal so any eating event between your breakfast and lunch your lunch and dinner or an eating event after your dinner this is how we typically refer to a snack however most people think of a snack based on the food that they're eating rather than as an eating event between a meal so most people might think if they have a pack of crisps even if they're having it at the end of the meal, that that's a snack. And how much of the population actually has snacks?

Starting point is 00:04:50 If we think about it as those like the eating between meals as you're describing, how common is that? So in the UK and the US, about 25% of our energy comes from snacks. 25% of all our energy comes from snacks. 25% of all our energy comes from snacks. So let's say, I know we don't like to talk about typical people, but let's take a typical person consuming 2000 calories. That is 500 calories coming from snacks. Now it does differ depending on age, where you live, but it also differs country to country. And I think this is really interesting because in the Mediterranean, for example, only about 14% of energy comes from snacks. Yet in some northern European countries, about 30% of energy comes from snacks, which is huge. But really importantly, in the UK and the US, 75% of the energy that's coming from snacks is coming from really unhealthy snacks, these ultra-processed snacks.

Starting point is 00:05:40 It's really cultural, isn't it? I mean, having spent time in Italy and Spain, France, you just don't see people having snacks at a bus stop. The idea that you'd have a meal on the go or a snack on the go is just not part of that culture. So I was quite interested in writing my book on potato snacks and things. There's a big section on crisps and found that actually the french eat more crisps than the british yes if you look at the actual wholesale amounts but they have them with their meal or they would have them as an aperitif just before the meal with with the drinks that are served just before so in way, it's sort of nearly at the same time as the main eating event rather than a completely separate eating event. And that might be

Starting point is 00:06:30 why they end up having less problems with those snacks than we do. But the idea of dividing your day into sort of six eating episodes is totally alien to many countries. And yet in the UK and the US, Australia can't, all the English speaking countries, it's standard now. And that's because governments for the last 30 years have generally been saying

Starting point is 00:06:53 eating little and often is a good thing. And I think that's what we have to bear in mind, that many people were brought up on that. And it didn't seem to matter what you're eating little and often. And as Sarah's pointed out, unfortunately, we've got into the position matter what you're eating little and often and as Sarah's pointed out unfortunately we've got into the position where what we're eating is pretty rubbish. It's France is interesting actually because so in France only about 10% of people snack if you

Starting point is 00:07:14 compare that to the UK 85% of people in the UK report snacking now the average amount of snacks in the UK that are consumed a day about about two and a half to three snacks. So that goes back to Tim's point that we're having about six to seven eating events. So occasions that we're eating throughout the day. You take Mediterranean countries or particularly France, they tend to be about four. It's interesting the difference. And I do remember my grandmother sort of talking about the fact that, you know, when she was young, the idea that you would eat food or even like drink drinks walking around was sort of socially unacceptable. So you just wouldn't have imagined doing it. And so that's clearly been a very big

Starting point is 00:07:53 trend. I have to say, when I go to Mediterranean countries, I feel like that trend is shifting, to be honest, Tim. So I feel like, you know, all of these things are more Americanized than they were. And there's this huge rise in obesity in France and elsewhere. So I guess that there's a sort of idealized past. Well, the graphs are all going in the same direction in every country. It's just the base was very different. We're just, in the UK and the US, so far ahead in the unhealthy scale that that's the difference. But yes, the pressures of marketing snacks is universal around the world. And I think

Starting point is 00:08:26 even with the best cultures, they're all under pressure to snack more because that's where the money's being made. So I'd love to talk about what happens when we snack. And Sarah, you spent 30 years really understanding exactly what happens in our bodies in the, you know, the minutes and hours after we eat. Can you help us to understand, you know, I've gone and I've met Tim and I've refused to have just a coffee. Well, he's not offered you a snack, has he? I agree. So I've gone and decided that I'm going to have, you know, a chocolate croissant to go with it. What happens at this point? So I think it's first important to say what the typical composition of a snack is. And so snacks in the UK and the US tend to be high in carbohydrates, high in refined carbohydrates and sugar, high in fat, high in unhealthy fat, saturated fat, and low in protein and low in fiber.

Starting point is 00:09:17 Okay. So what's happening is when you're eating a snack, you're eating a high refined carbohydrate snack, a high saturated fat snack. And so what this does is it causes an increase in circulating blood sugar that peaks around 30 minutes, returns to baseline around two hours, and often dips as well below baseline. Then the fat that's in the snack causes an increase in circulating blood fat that kind of creeps up throughout the day if you're having multiple eating events. So you're in this kind of state of metabolic chaos is the best way to think about it if you're having lots of snacks. And that's because these snacks are basically hitting you much harder

Starting point is 00:09:54 than a sort of regular, let's assume it's not at a sort of ultra processed meal, but a sort of reasonably plant based, reasonably fiber rich food. These snacks are just sort of hitting all of these things much more than a normal meal? So it depends obviously on the composition of the snacks. Not all snacks are the same. So I'm talking about the unhealthy snacks, the snacks that 75% of people are eating. Most people are eating. Like what, Sarah? Give us some examples. So light crisps, light cakes, light chocolates, light pastries. So particularly high in refined carbohydrates and particularly low in fiber and protein. And a lot of these bars and things like this as well, you know, I know Sarah, you told me that they're actually very similar, right? So they look like

Starting point is 00:10:33 they're really healthy for you, but actually they're behaving in a similar way? A lot of the time. So it depends on the bars. Some of the bars do have whole nuts in them, which will behave slightly differently. But most snack bars, again, what will happen is you'll absorb all the nutrients really quickly into the bloodstream. So you have this really quick, rapid rise in circulating blood sugar. That sets off a cascade of quite unfavorable effects, including inflammation. What often happens is you also get a dip in blood sugar about two to four hours after having these refined carbohydrate snacks and we know from our own zoe predict research that this causes an increase in hunger it causes an increase in energy intake and it also causes you to eat more at your

Starting point is 00:11:17 next meal and you've talked a bit about this in the past haven't you this sort of thing you're on a sort of roller coaster where you're hungry so you go and eat this like very refined thing because you're like oh I really need this energy like your blood sugar shoots up then it crashes a few hours later and makes you hungry so therefore you do it again and so you're on this sort of miserable repetition of something which is just sort of banging and banging away at your your body is that yeah absolutely and I think something that else that's quite interesting that happens is is often your increase in blood sugar isn't quite high enough to suppress your hunger hormone so you have a hormone that circulates called ghrelin and now if you have a big meal the increase in blood

Starting point is 00:11:56 sugar causes an increase in blood insulin and that causes a suppression of this particular hormone but you don't suppress it enough. So you carry on feeling hungry as well. And I think that's another small problem with multiple snacks. Sarah, a lot of these snacks that people are having, most of them are ultra processed, which means they're using extracts of real food to sort of camouflage real food. And we know those chemicals are bad for the gut. And how much is that an effect, do you think, on this repeating cycle and making you hungrier? So I think there's lots of problems with ultra-processed snacks that are the same

Starting point is 00:12:36 apply to any ultra-processed food. So you have the problem that they tend to be able to be eaten more quickly. And we've done a podcast on eating rate before so that actually you tend to eat them about 40% faster than if it was a whole food version of their food. What then happens is you're consuming more calories because you're not allowing the time for your hunger signals to go to your brain. So it takes about 20 minutes for your hunger signals to go to your brain to say, well, I'm full, stop eating. We also know with those kind of old processed snacks, they get absorbed in a slightly different area of your gut. So they get absorbed higher up your gut. And so you, again, release less of these fullness hormones. So you're not getting

Starting point is 00:13:21 the same signals going back. And I can hear your tummy rumbling. Do you need a snack, Tim? I do. I skip breakfast so I could do my time of street eating. So yeah, I'm very in need of, I'm not sure one of your snacks, maybe I will go for one of my healthier snacks. And Tim was a bit punchy earlier. So now we know he hasn't actually had any food. He's hungry. Even Tim can get hungry. That makes me smile. I've got high energy levels i'm good um but as well as with many of these the additives you know the emulsifiers we know you know as i mentioned earlier they tend to be higher in carbohydrate higher in unhealthy fats lower in protein and lower in fiber but interestingly if you give people healthy snacks and I've done a study at King's College where we fed people for six weeks, either healthy snacks, which were nuts. You know, I like my nut studies.

Starting point is 00:14:12 You need to carefully define healthy snacks, but we're going to get onto that, I'm sure. And we provided 20% of energy to people either in the form of nuts, or we provided 20% of energy to people in the form of a typical UK snack. And we actually spent a lot of time developing this typical UK snack, which obviously I gave in the form of muffins, but it was representative of the nutrient composition of, let's say, you know, some Walker's crisps, some Cadbury's dairy milk, some cakes and pastries. And when we fed the nuts for six weeks to individuals, we had a significant improvement in the functioning of their blood vessels.

Starting point is 00:14:50 We had significant improvement in their heart rate variability, which we know is a really novel marker telling us about heart health. And we also had improvements in cholesterol. When we fed people the typical UK snacks, we had no change in any of these outcomes, which we would hope for because they're representative of what people are actually consuming. At this point, we usually remind you about getting 10% off Zoe membership with the coupon code you can find in the show notes. Though I would love for you to do that, I'm actually here to tell you about a common request we receive from people like you. It goes something like this. I've just discovered the show and now I listen each week, but I don't have time to go back and listen to all the previous episodes.

Starting point is 00:15:35 Could you share some of the most impactful tips led by science and put them into a free guide that you can download right now. To get yours, simply go to zoe.com slash free guide. And Tim, what about what's going on inside the gut? So I think it seems if this is like 25% of the food that people are eating, then actually the snacks that we're eating are likely to have quite a big impact there. Yes. I mean, statistically, most people in the country are eating unhealthy snacks. Most people are eating high amounts of ultra-processed food. So that's boosting the already high levels of intakes of ultra-processed foods and chemicals in the population. And we have the highest levels in the UK.

Starting point is 00:16:31 In Europe, the US has the highest in the world. These figures are going up and snacks are a major component of that because people don't think of them in that context. They don't realize how many they're having. They don't realize because often they have healthy labels on them saying they're high in protein or they're low in salt or less sugar because they've got artificial chemicals instead. So people often might think they're having healthy snacks and actually they're contributing to this general increase in chemicals, all of which we now know have adverse effects on the gut microbes, whether it's the emulsifiers, it's the artificial sweeteners, some of the preservatives, some of the gums, some of the xylatols, all

Starting point is 00:17:12 these sugar alcohols, all these things, many of which we still don't totally understand, negative effects on the gut, which are going to give long-term problems. So not the sort of problems that Sarah's talking about, the immediate hunger, et cetera, but reducing the state of the gut microbes, reducing the immune system, inability to respond properly. And so that's one major factor why the gut health of Western populations is getting worse and we're getting more susceptible to diseases and cancers and aging, et cetera. And it's a small, slow process. It's not something you can sort of see immediately, but all the experimental studies, when you actually put these chemicals together into gut models, you show this. So I think one of the interesting things about this topic is that like a lot of areas of nutritional science right it's quite controversial you know as sarah's told me before like it's not something that's been studied in a

Starting point is 00:18:09 lot of detail and of course part of that is it's really it's been historically very hard to measure what people are actually doing at home before we had phones and these devices and you know sort of very large-scale studies so before sort of revealing your own personal views on snacking, I thought it'd be fun to maybe just start with like, what are all the reasons why it might be bad? And then maybe we talk about the other side. So, you know, what are the arguments for why snacking actually is unhealthy? I think when we think about snacking, we need to break it down first, Jonathan, into three different areas. So firstly, is it the snacking frequency, i.e. having lots of meals throughout the day that's bad? Is it to do with what we're snacking on, so snacking quality?

Starting point is 00:18:55 Or is it to do with the timing of snacking? And this is something that we've been looking at with our own ZOE predict research. But also there's other randomized control trials that have looked at this. And I think an important place that perhaps we could start is around the eating frequency. I think it's really clear from what Tim and I have said. Which in normal words is just how often do I eat something? How often do you eat? We call it in nutrition research, you know, you're eating events or eating occasions. What is the concerns about this sort of snacking frequency, Sarah?

Starting point is 00:19:23 So originally, the data actually showed that people that had more eating events, so snacked more frequently, actually had lower BMI and were healthier. And so this is why I think historically people were encouraged, maybe 20 years ago or so, to actually have little and often. Yeah, that sounds good. Grazing, not gorging, it's called. Weighing less, that sounds... We were supposed to be like cows rather than like lions.

Starting point is 00:19:51 That was a sort of thing. Oh, I love that. It's never a good... I originally can see that being like a cow rather than a lion doesn't really sound that good, does it? Well, I certainly eat like a cow. Tim eats like a lion. And so what is the view now?

Starting point is 00:20:04 So when researchers actually went back and looked at all of the data, what they realized is that they were including a lot of what we call under reporters in the analysis. So lots of people actually don't report what they eat very accurately. And so there were lots of people that were actually reporting that they were eating only half of what in reality they were eating. So if they excluded from their analysis all of these people that had not really been telling the truth about what they were eating, what was quite clear is that the people that were eating more often, so more of these eating events, tended to be consuming more energy and they tended to have a slightly higher BMI. So they were slightly overweight. What's really interesting, though, is that over the last 10 years or so, there's been

Starting point is 00:20:50 lots of randomized control trials now that have been looking at how people behave in terms of their health, depending on whether they have three meals a day, or whether they have six or even up to nine eating events a day. And all of this data seems to show that as long as people are snacking on healthy foods, there doesn't seem to be any difference in either weight or any what we call cardiometabolic health outcomes, so factors related to cardiovascular disease or type two diabetes. And there seems to be no difference depending on whether you're eating three meals or having six or even up to nine eating events a day. Now that's if they're eating healthy meals, which 90% of you don't. Okay, so that's why we needed to break it down into the three areas. So firstly, is eating

Starting point is 00:21:33 multiple times throughout the day bad for us? And I think the evidence shows if it's on healthy food, then it's not unfavorable. And our ZOE predict research really clearly shows this as well, that for people that are eating unhealthy snacks, rather than snacking on unhealthy food, that there's no unfavorable effect on any of these outcomes. Can you caveat that with breakfast though? You know, my views on skipping breakfast and the meta-analysis that shows that the breakfast might be the exception. So I think what we're talking about is during the day, between, say, lunch and dinner, if you have snacks and they're healthy,

Starting point is 00:22:15 there's no evidence that that's particularly bad. But there is accumulating evidence that skipping breakfast and having a longer fasting period, and so people having two main meals rather than three because of that breakfast are slightly healthier and certainly no worse which is what we previously believed to be the case so i think again it comes to the point on timing and that's i just want to raise that caveat that breakfast might be the exception to this whereas snacking events during the day sarah's you know spot on that that's exactly right thank you tim can we uh make sure that i get to hear tim say many times that i'm spot on can we cut that clip that's the first time in five years

Starting point is 00:22:59 so you were saying that one part of this is frequency. So how often you eat? What else? Then there's the quality, which we've talked about. So given that 75% of snacks are heavily processed and we know are unhealthy for us, that's where we have a huge problem. And given that we know that if they're high quality snacks, they don't tend to have any unfavorable effects if we're having multiple snacks. And then even from like randomized controlled trials, like the ones that I've run at King's, where we give people snacks, but healthy snacks, where we see an improvement, again, is evidence to show that the type and the quality of snacks are really important. And then the third factor is the timing. And I think this is what's really interesting and really important. And I think this is something that people should really try and modify rather than worrying about, you know, how many snacking events they're having.

Starting point is 00:23:51 So as well as modifying the quality of the snacks, the timing of your snacks. And our ZOE predict research really clearly shows that if you're snacking late, so after 6 or very late after 9 p.m which actually 35 percent of people do that it has really unfavorable impacts on your health and there's lots of other randomized control trials to support that eating late in the evening on these unhealthy snacks actually has an unfavorable effect on our health so that's yeah i mean and that's very much a culture you know you've seen this if you watch goggle box everyone's watching tv and on their sofa and they've got plates of sandwiches and cakes and uh with their mugs of of tea and coffee and in many parts of the uk this is the tradition you can't really sort of watch tv unless you've got some snacks there. And

Starting point is 00:24:45 this has become part of our tradition and culture. It didn't used to be. And I think it's exactly the worst time to be eating these foods and being promoted. I literally have Tim's voice in my ear every night as after dinner, you know, I go down, sit in front of the TV and eat half a bar of dark chocolate, which also I was told is really hard to eat half a bar or two thirds of a bar of dark chocolate, but it's that nobody's trying. People aren't trying hard enough. I managed it. You're the exception to the rule. Now it is dark chocolate. So it's clearly a lot better than a lot of these things. And I would like to talk a bit about more about the snack quality. Cause I think I've just had a lot better than a lot of these things. And I would like to talk a bit more about the snack quality because I think I've just had a lot of personal experience about the way that by swapping

Starting point is 00:25:29 out the sorts of snacks I've had definitely changes the way that my hunger and my mood affects during the day. But I do always think of Tim as I'm like, yeah, now I'm still going to have that dark chocolate. And I try and make myself feel better by thinking that in Spain, they haven't even had dinner yet, Tim. I went to Spain over the holidays recently, and they eat incredibly late. So they clearly are eating until very late. So do we know how much of this again is about, there's these two different things here, aren't there? One is like the quality of your snacks. And you're saying that almost everybody's eating like very poor quality snacks. So it's sort of obvious then if you're eating more of the snacks, you're just having a much worse diet. So

Starting point is 00:26:08 that's obviously a very big part of this. And then there's also these things you're describing about the frequency and how late they are. And that you're saying, you know, each time you eat this, you're still going to have these impacts on blood sugar and blood fat. If somebody's listening to this, how much of this is about the quality of the snack, do you think? And how much is these other factors should they be worrying about? Can I pick up on the time of day quickly just so that we can illustrate just how important that is beyond these peaks and troughs that we talk about with blood glucose? And there was a really interesting study that came out last year that I think really nicely illustrates what's going on by eating late in

Starting point is 00:26:49 the day. And in this study, they gave people exactly the same food over exactly the same time period, but half of the people had the food slightly earlier in the day and the other half had the same food slightly later in the day. So they were told when they could eat. Is that they were sort of controlled, like you can eat between this time and this time? Yeah, exactly. Those people that are having it later in the day, despite eating late in the evening,

Starting point is 00:27:14 woke up the next morning lots more hungry than the people that were finishing their food a lot earlier in the day. So eating late in the day has a couple of different unfavorable effects. One is you're waking up feeling more hungry. So I don't know whether you wake up feeling more hungry probably than Tim because you're snacking late in the evening. But also we know that it's unfavorable because it goes against your body clock in terms of how you metabolize the food. So you get these unfavorable peaks and troughs that we talked about. But in spain interestingly

Starting point is 00:27:45 you know i spent a lot of time in there as well and yes they eat ridiculously late but most of them don't have breakfast or they would have a coffee or a tea as their only breakfast so they wouldn't be having anything substantial until lunchtime so the problem is someone from the uk or you know us going to these countries they're used to their their timing and going to their same bedtime and they'll be pushed to have uh you know food much closer to going to bed which isn't healthy either so you do need this this time when everything switches down and it goes back to this this whole time restricted eating idea of having this at least a 12-hour window between your overnight meals before you ingest anything substantial.

Starting point is 00:28:31 Can you remind us why we now think that having that sort of long window of not eating overnight is important? There are a number of reasons for this. One is that the body needs time to recover and that it's part of our circadian rhythms that all the cells in our body have the same 24-hour clock and they have periods of work and then rest and repair. So all the cells are repairing during that time. They don't want to be confused with new food being sent down as if we've got to suddenly wake up. So all the cells in our body have a repair mechanism. All the general debris of cellular work gets cleaned up in that time. And our gut is exactly the same. So our gut microbes completely change composition when we're not eating. They send out like a cleaning team that goes and cleans up our gut lining. And that improves our efficiency and everything's clean and ready for the morning.

Starting point is 00:29:32 And it helps our metabolism. That's our energy management system. So the more we do that, more we're in sync with our natural rhythms and the body is in complete rest and our gut is in complete rest. So that's the sort of general concept. And Tim, do you know something that's really interesting, I think, with this whole idea of time-restricted eating and giving your body a rest is studies that have had people consuming exactly the amount of energy, but where some individuals consume in a shorter period, so they have a greater rest, despite having exactly the same energy intake, the people that have the greater period of rest actually have improved metabolic outcomes. So they have less inflammation, they have better

Starting point is 00:30:16 glucose control, better blood lipids. And that's despite eating exactly the same. I think that's really fascinating. And more energy. And that's what our Big If study showed, that despite this, energy levels, mood improved. People weren't sort of hangry. I was going to say, my personal experience out of this, which is really interesting, is I don't really like intermittent fasting. I tried it for that study and I turned out

Starting point is 00:30:41 these things are always personalized. I'm in the less than 50% who really struggled with it. But I discovered that I could actually go to the gym in the morning and do like a normal session at the gym with no breakfast and perform exactly the same as I had done with breakfast. And I had always assumed, you know, think about all the marketing I've been exposed to since I was a small child that like, oh, you need to have your energy before you go and do exercise. And that's the, you know, the energy drinks, right? We're all told, well, you better have that before you go and play football or whatever. And so I was genuinely really shocked.

Starting point is 00:31:16 So I thought, well, I'm going to do this intermittent fasting. I can't eat anything until midday. I'm going to go to the gym in the morning. It's going to be really difficult. And actually it was fine. Because our ancestors, you know, didn't say, well, I can't go hunting until I've had my breakfast. Well, you can't, you know, you can't get your breakfast until you've been hunting. So, you know, it's like, obviously that can't be right.

Starting point is 00:31:37 So I think that's really interesting. I would have starved in those days, Tim. You would have starved, yeah. Waiting for the berries to drop off the tree maybe. I'd have been waiting for you to bring me my breakfast. But I thought that's interesting so it sounds like when you're talking about snacking one thing is you know if it's it is snacking just extending the total amount of time that you're eating and if that suddenly really shrinks the amount of time your body's able to rest that's one sort of big potential negative. If we switch to sort of

Starting point is 00:32:05 between the time when you're going to have your first meal and your last meal, I think one thing I'd love to ask, we had lots of questions about this is, what about the impact of snacking on weight gain? So lots of people said, well, surely I'm snacking more, I'm going to be eating more calories. So it's sort of obvious, right? People who snack are going to put on more weight. That's really bad for their health versus people who shouldn't snack. And therefore snacking is always going to be bad versus not. Is this right? So I think the population studies show that people that snack more do eat more calories, but the clinical trials do not confirm this. So it doesn't play out in these

Starting point is 00:32:48 very tightly controlled trials. And there was some interesting research where individuals were given on one day a meal of a set composition, and then they monitored how hungry they felt for the next four hours. And then four hours later, they were given free access to whatever food they wanted. Then on another occasion, the same individuals were given the same meal composition, but split over a number of eating occasions. So over the four hours, they were given, I think, about six times. And then what they found was that although during that four-hour period, they were still a little bit hungry throughout the four-hour period, at the end of the four-hour period, they were still a little bit hungry throughout the four-hour period. At the end of the four-hour period, they were less hungry. And so they didn't go on to eat quite as much of the next meal as the people that had eaten the really large single meal earlier in the day.

Starting point is 00:33:40 Hi, I have a small favor to ask. We want this podcast to reach as many people as possible as we continue our mission to improve the health of millions. And watching this show grow is what motivates the whole team at Zoe to keep up the really hard work of creating new episodes each week. So right now, if you could share a link to the show with one friend who would benefit from today's information, it would mean a great deal to me.

Starting point is 00:34:04 Thank you. So what you're saying, and I want to make sure I've got that right, is if people have snacks, then actually they might eat less of the following meal. So it's sort of balancing out over time. Is that what you're saying? Rather than like, it's just guaranteed if you eat snacks, you're going to eat more calories over time. Over 20 years, you're going to weigh 20 kilos more because you're a snacker than the person who doesn't snack. I think it's really variable though, between individuals. That's just one study, but I thought that was really an interesting one to illustrate. And what about the impact on like your blood sugar and your blood fat? Because,

Starting point is 00:34:40 you know, there's a lot of people who have been saying, you know what, everything is about what happens to your blood sugar. You know, if you think about your blood sugar and keep that really stable, then all your health problems will be solved. And it seems pretty obvious that if you were just to eat small amounts all the way spread through the day, right? So have no really big meals, but have 10 snacks, you're never going to create the same sort of big spikes and dips as if you're having them in a smaller number. If that's the case, that would suggest that having lots and lots of snacks would be much healthier than having big meals. What does the science say about this? Well, that was the old-fashioned view. That was this grazing versus gorging was based

Starting point is 00:35:20 sort of on that idea. And that has been largely disproved by the real life studies. Sarah's probably got a view on why that is. Yeah, I was going to say, how do we understand that? So I think our blood sugar response is very complicated and there's lots of different features to it. And one of the features that we know is really important is the fluctuations, which is what you're talking about, where they might be small, but you have these kind of fluctuations throughout the day. So it's like a kind of mini rollercoaster almost. What we know is that if you have lots of fluctuations, even if they're small throughout the day, it seems to be associated with unfavorable

Starting point is 00:35:59 long-term glucose control. So you have higher levels of something called HbA1c, which is a marker of elevated glucose. You have a poorer insulin sensitivity. What we do know though is that if you have really big peaks in blood glucose, it does cause a bigger peak in inflammation than if you had these small peaks. What we don't yet know is which is more unfavorable. We don't actually know whether a big single peak or lots of little ups and downs is worse for us. And this is the kind of thing that we're currently exploring in our ZOE predict data. Something that was really interesting that I read quite recently that picks up as well on the point Tim made earlier about this whole idea of personalization around snacking, not just on the basis that you and I want to snack

Starting point is 00:36:46 and Tim doesn't need to snack, is that we see that people are preconditioned to be able to respond to snacks if they are typical snackers. So there's been research where they've taken people like you and I who snack regularly and then put them on three meals a day or taken people like Tim who just has his two or three meals a day and put people like Tim onto lots of regular snacks. And it really mucks up their metabolism because your body's quite clever in a way, almost predicting, oh, I'm meant to be having an eating event soon. So for us, our bodies are predictive or predicting that we're going to be having eating events and seem to respond well to it. And so when we go on to Tim's style of eating, it's hard for us and our responses might not be as good. Likewise, when Tim goes on to our style of eating, which I'd love to

Starting point is 00:37:34 try out, actually, that would be a fun experiment. I think he'll be happier because he's eating lovely food all day. But actually, he won't handle it as well as us and i think that's really interesting and the routine that our bodies have all of these routines i mean one of the things that i've definitely sort of realized through all the stuff with zoe sort of be more aware of my body is you start to become more aware of whether you're hungry or not and i think that i was definitely sort of just trained by the environment. I mean, to never, ever be hungry, right? Like that's just a bad thing at all points.

Starting point is 00:38:10 And I think starting to understand a little bit between, oh, I'm really hungry and definitely I should go and have a snack versus like, I'm a little bit hungry, but actually that's all right. And potentially that's even going to decline. I was having a Jewish mother, so you can't ever go hungry. So that's right. That's definitely right. So maybe just to sort of wrap up the pros and cons, I'd love to talk a little bit, Sarah, about sort of this new Zoe research that you've been working on, specifically

Starting point is 00:38:35 on snacking and sort of what have we found in our latest papers there and why is that actually quite exciting in terms of, you know, why is this quite novel and the scale sort of really something we haven't had before so in the new zoopredic research that hopefully will be published by the time this comes out we looked at the snacking habits of participants from our predict one study so this was just over a thousand individuals and we tried to tease apart the impact of these eating frequencies so the number of times that we're eating in the day the eating quality so the snack quality and then the timing of the snacks because this actually hasn't been done before people have either just looked at how does eating frequency impact health how does snack quality impact health or how does timing of day of eating

Starting point is 00:39:22 anything impact health and sarah some people listening will say well it's a thousand people. That doesn't sound like a very big study. That's a big study for nutrition research. Before I took part in all of the ZOE research, most of my studies were in about 20 individuals. Now, these previous studies were randomized crossover trials. And sometimes you can detect really meaningful differences in information from even 20 individuals. So to have a thousand individuals where we were collecting data in a really tightly controlled way in Zoripredict, I think is not to be sniffed at. What have you discovered? So what we found was that the frequency of eating was not associated with any unfavorable health outcomes. So having regular eating events throughout the day was not unfavorable.

Starting point is 00:40:12 What we did find, though, was the timing of the eating was really important. So timing of the snacking and also the quality. And so timing, this is again meaning that if you eat really late at night or what does that mean? Yeah, so what we found was that 35% of people were snacking after nine o'clock in the evening and those people that were snacking after nine o'clock in the evening even if they were on healthy snacks had an unfavorable association with body mass index so body weight and other factors related to cardiovascular disease such as our blood fats and our blood sugar. What we found, though, is that people who were eating their snacks earlier in the day,

Starting point is 00:40:50 if they were high quality, didn't have any of these unfavorable effects. And I think that's really, to me, was really surprising, but also, I think, for me, sort of reassuring, which suggested that if you were able to switch from the sort of snacks that almost everybody is eating today to high quality snacks, and we can come on to that in a minute, then this suggested that you might be fine with that, which doesn't mean you need to be encouraged to snack like that. But my takeaway was I've made a big shift in the sort of things that I eat. And so I have a big bowl of nuts always next to the computer. And mid-afternoon, often I am hungry and I will eat a whole bunch of nuts. And I find that reassuring

Starting point is 00:41:37 also because it's definitely changed the sort of the dynamic of my hunger because, you know, lots of people always have said, well, nuts, they're really high in calories, they're really high in fat. You're definitely going to put on lots of weight if you're eating those. But interestingly, what I see the difference between that and what I used to eat, which would have been very much high-carbohydrate food, is an hour or two hours later, I'm just not really hungry. So you eat a whole bunch of these nuts and you just feel full for a lot longer. Whereas when you're eating these sort of high carbohydrate meals, at least in my case, you know, it's definitely feeling full temporarily and then tending to have this crash, which I now know, like I really actually do have with my blood sugar. So does that mean that everyone should just be like eating nuts all the time,

Starting point is 00:42:26 Tim? Should we be positively encouraging snacking or what's your view on this? No, I think we should have a much more nuanced view on it. I don't think we need to snack. Most countries don't snack. And I think we've got to realize we're the outlier because we've been pressured by the food industry to buy these pseudo-healthy products that are generally really bad for us. And we're not being bombarded by nut manufacturers to eat stuff. We're bombarded by companies selling high-protein bars that are full of artificial chemicals and sweeteners and things that are really bad for us. So in general, I would say, eat your meals properly, spend more time having a full proper meal, just as they do in Mediterranean countries, have time to digest it, get the full appetite. But if there are people who like, you know, perhaps one in three people that really feel

Starting point is 00:43:23 the need that they do need something between meals, they can't quite get enough like you know, perhaps one in three people that really feel the need that they do need something between meals, they can't quite get enough like you guys, then yes, snacking is okay, as long as it's not late at night, it's not after your main meal, and you pick the right stuff and you pick unprocessed, you know, fruits, vegetables, nuts, seeds, etc. And you don't go to something in a packet that is generally going to be bad for you. And I think it's really important we listen to our hunger signals. And so if I take my two children, for example, my daughter eats probably three meals a day and some snacks when she first gets home from school. She sometimes doesn't even have her breakfast on a weekend till midday. So she's a little bit more like Tim.

Starting point is 00:44:06 I've always taught my children to eat when they're hungry, but not out of habit. My son, however, is like me and eats probably every hour to two hours. Now, they're both slim, they're both healthy. And I've allowed them to make those choices to listen to their hunger signals. And I think that that's really important that we make sure it doesn't mean that people get into the habit of snacking just out of habit, but they do it because they're actually feeling hungry. And Sarah, I feel like Tim probably still has a bit of a bias towards like, you know, not snacking unless you really need to.

Starting point is 00:44:44 Like, are you in the same place or are you, I feel like there's a little bit of gap here between sort of your relative views on snacking with it. So not if you can do it in the middle of the night, but, you know, between breakfast and dinner, say. Well, Tim's wrong, I'm right. I think that both Tim and I have agreed definitely not to snack late in the evening. I think that we're agreed that there's good evidence to show that if you have a good fast

Starting point is 00:45:14 period and a small eating window, then it's healthy for you. I think that I'm a little bit more positive on snacking, providing it's healthy snacks than Tim is. But that's coming from a person that needs to snack, that I know that if I don't eat for two or three hours, I get really hungry. And so it's very difficult sometimes to disentangle your own personal feelings, you know, from this as well.

Starting point is 00:45:42 Yeah, no, I'm happy to go along with that. We all have our personal biases and that does determine, you know from this as well yeah no i'm happy to go along with that that we all have our personal biases and that does determine you know how we view these things but i think it is important to look at a global perspective also look at our ancestors our ancestors were not eating six or seven times a day and that's how our you know we've we've evolved And I think we need to realize that and realize a lot of our choices, our habits, customs, culture, and advertising. And I think we have to be just very aware of that and realize that you certainly don't need to snack for most people.

Starting point is 00:46:18 Otherwise, humans would have evolved very differently. Yeah, I think as well, it's important to be aware that snacking frequency is increasing and it's increasing in the consumption of these unhealthy ultra-processed snacks. In the 70s, we had about 140 calories less from snacks than the amount that we're having now. And it's just continuing to increase. When I went to school in the 60s and 70s uh we didn't bring any snacks to school and there was no real you had there was some school milk which always was a bit smelly

Starting point is 00:46:52 and you know not very nice but but basically kids were allowed to go until lunch but now you talk to parents of of kids and it'd be horrified the idea of sending a little Johnny to school without his little box and having some midday carbohydrate sugar. It is crazy how it's become part of the norm when actually it never was. And this is all marketing. I'd love to talk about actionable advice. So I think there's been a really great explanation about sort of where the science is. I think lots of people will be listening and say, okay, so what should I do that's different? And maybe we could actually start with actual snack options. We had lots

Starting point is 00:47:35 of questions from our listeners. And maybe to start with the first one, what do you think about crisps, chips, nuts, and fruit as snack options? Well, it all depends because within those categories, there is actually a big range. So you take fruit. I used to snack on bananas. But since doing my Zoe test, I've seen that actually scores very badly for me, a banana as lots of sugars that are easily released. So I'd be better off snacking on apples or pears,

Starting point is 00:48:07 for example. And other people might have lots of examples. If you snacked on mangoes and things like this, it could be quite bad for your blood sugar all the time. So the choice is important. Obviously, carrots and nibbling broccoli is always going to be good for you. But maybe not massively appealing all on its own. Exactly. Unless you are a sheep or whatever. I'm not eating Tim's snacks. No, I'm not saying I do nibble on broccoli.

Starting point is 00:48:35 Just broccoli seems a bit. I'm a big fan of nuts, and I think virtually all the nuts that are on offer, nuts and seeds, are healthy. I don't think there's really any real exceptions unless they've been chemically treated and that you do get some of these nuts that are roasted in a bit of sugar and things there to be avoided. But generally plain ones, you know, look out if you have a sensitivity to salt, you might want to reduce some of those. But otherwise, all those nuts and things are really healthy options and have been discussed. They might actually reduce the amount you eat subsequently, and they're fantastic sources of protein and fiber and other nutrients. Crisps is an interesting one, and the UK goes through enormous amounts of crisps. There's potato chips in the US.

Starting point is 00:49:18 Potato chips. And again, there's a huge range actually in the quality of them. So the vast majority are highly processed, lots of artificial ingredients, etc. Not very good for you. Some of them are not even made from potatoes. Can you be a potato crisp without coming from a potato? Well, most people think there's a brand called Pringles made by Procter & Gamble that is one of the best-selling ones in the world. And they are totally created in a factory made from composites of all kinds of different vegetables, extracts, to create something that looks like a potato but actually isn't. So that's a good example of the worst kind of potato-ish snack. And you go to the other extreme,

Starting point is 00:50:05 you can get potato crisps with the skin on, which adds fiber, and they can be cooked in extra virgin olive oil. And actually, there is just potato, just olive oil, and just salt, and they are relatively healthy compared to other snacks. So I think it is about understanding, again, the quality of the food you're eating, not making too many assumptions, but there are, within those categories, really good ones

Starting point is 00:50:36 that people can have if they do feel the need for a snack, or they just want to occasionally enjoy food, which I think we all need to do. This is not about prohibiting stuff. It's about having with friends, you know, a beer or a glass of wine. What do you choose to serve at that time? Definitely go for high quality potato chips, crisps and a bowl of nuts. I don't think anyone's going to argue with that with a few slices of apple. But, you know, in general, I think everyone would agree do you agree sarah i would agree and i think something

Starting point is 00:51:09 that we need to bear in mind is for people that do snack it does account for a huge proportion of their energy intake so it's actually a fantastic simple dietary strategy to improve the quality of your diet most of the other meals that we have, for example, our dinner, we tend to have, or the majority of people do tend to eat this as part of either a family or a social setting where you have less control over the food. But with snacks, they tend to be eaten in isolation. They're under what we call your own personal choice. So it's a really good way to improve the quality of your diet. And actually, a really interesting finding from the ZOE predict studies that I was really shocked by is that 40% of people who have a high-quality diet actually have a really poor quality intake of snacks.

Starting point is 00:51:55 So I had assumed that if you have a high-quality diet, well, you're going to choose healthy snacks. But actually, we found that wasn't the case. It's interesting. So you've got this big difference between what you're eating at your breakfast and your lunch and then the snacks, which doesn't surprise me so much because I guess this is also the sense that it's a treat. But I guess the other thing that just like my personal experience that we haven't really touched on very much is the way that, you know, your previous meal may affect your snacking and

Starting point is 00:52:24 also just, you know, where you are. So, you know, if you're at home the whole time, it's a very different experience, right? Than if you're out, you know, and about, and, and so maybe we could just, just cover, I guess, firstly, that effect of the previous meal, because one of the things I've noticed is that before I started to change my diet, I would tend to get really hungry a couple of hours after any of my meals. It's definitely like this very strong desire to eat. And that was quite a... So the snacking itself is affected, it seems to me,

Starting point is 00:52:55 like in my personal experience, by what I ate. Is this just me or is there some real science behind this? Well, we've seen with our own ZOE Predict study that what you have for breakfast can determine your blood sugar response to what you have at lunchtime. And that might go on to also impact how hungry you feel as well after that lunch meal. So I think that there's some evidence around that. What we also know is that if you're having not the right balance of protein and fiber in your meal, then you are going to feel more hungry more quickly and then you're going to more likely need to snack. So, yeah. And also sleep is the other thing. So if you're going to poor night's sleep, you're going to be searching for that high carb snack and you're desperate for a Kit Kat or a chocolate bar or

Starting point is 00:53:48 whatever it is when you really shouldn't. So your brain is playing tricks on you and trying to force you into some of these situations that, yeah, we've got to realize. So you've got your own environment that you're controlling. And then as you said, the food environment you're in. If you're an area and you're surrounded by sweet shops and kiosks and you're controlling and then you also as you said the food environment you're in if you're an area and you're surrounded by sweet shops and kiosks and that you know you're hungry and that's all you see is this range of confectionery or stuff in you know it's very hard to resist it and we do have in this country a really different food environment to many other ones we keep comparing the mediterranean. They just don't have that. You know, you're walking down the road.

Starting point is 00:54:27 You don't have those opportunities as much to just go and buy something rubbish. And if you don't, often if you go another half an hour, you've forgotten about it. You know, it's worn off. So the food environment, I think, is really important as well as, you know, what you eat. I was going to say, my personal experience around this,

Starting point is 00:54:44 because, you know, Tim often talks about how he would like to skip breakfast but for me like eating breakfast and having a big breakfast means i have like a large part of my total eating where i have complete control over it because just myself i'm not having to share that with any other parts of the family i'm at home so i've been able to have the ingredients that i want because actually you know if you're out you know in town you've got to figure out you're going to a family. I'm at home, so I've been able to have the ingredients that I want. Because actually, if you're out in town and you've got to figure out and you're going to have your lunch, actually, that can be much harder to have control. And so I do think often a lot of this can be quite theoretical because it's based on scientific studies where things are very controlled.

Starting point is 00:55:19 But my experience on the actionable advice is it's also a lot to do with your own lifestyle. So if you're going to be at home the whole day, then actually, yes, whether you eat at 8 a.m. or midday i'm in town and you're just surrounded by lots of places selling delicious looking pastries and all the rest of these these things and there's almost there's probably no options that are as good as the one you would have done before yeah well that's one of the dangers of of skipping breakfast is you've sort of got to know what you're going to have for lunch and where you're going to be. And so you're not going to be tempted as you are hungrier than normal. And I think that's another issue. I think, you know, as we're changing our eating habits, hopefully people, you know, are wanting to be healthier. I think this is what, and also our work life balances, you know, where we're working, where we are is changing. These are things everyone needs to be thinking about. Well, I think we've covered a lot of ground today. And I'd like to try and sum up,

Starting point is 00:56:30 which is more challenging in person, because I haven't been able to make the same notes as I might do if we were virtual. So, you know, I think we started by saying that the way that we snack in the US and the UK is both very different from the way we would have done 50 years ago and very different still from many other places, particularly comparing with sort of the Mediterranean culture that we know tends to come out with the healthiest food. I think that amazingly, almost everybody is snacking. You said, I think 85% of people are snacking. And I think the depressing thing is only 25% of those people are snacking on foods that are seen as relatively healthy, which means 75% are eating really unhealthy, very ultra-processed,

Starting point is 00:57:12 and that many people are eating worse snacks than they are in the rest of their meals. So this is something that's really pulling down the quality of their food. That there are a number of different reasons why snacking might be affecting us. So one is that it might affect the amount of time that we're just eating overall. And it sounds like there's really quite a big emerging consensus that you'd really like to have 12 hours where you're not eating. So if you're snacking into the evening and then you're having your early breakfast, this could be really reducing the time when you're letting your body rest. So I think it sounds like that is, you know, it's new and I know there's more studies going on, but it feels like you're both quite convinced about that. The second thing is eating quality

Starting point is 00:57:53 and that, you know, the most important thing is like, what is it that you're actually eating? And that there are real opportunities to swap from the snacks that people are eating. But the problem is that almost everything that you might get in a store that says it's a snack is probably bad. And you've really got to go back to things that look more like real food. We've talked a lot about nuts. We've talked about fruit. We've talked about things that are less processed and that there's quite a lot of personalization

Starting point is 00:58:21 in this. And then I think the third thing, which is obviously the most controversial is sort of the number of times that you're snacking. And I think that, you know, Tim's preference would be, if it's not a big problem for you, don't really snack, eat these regular meals. Sarah, I think you are more relaxed about this as long as you've got that long gap overnight and the quality is there. And I believe that we hope to do some more sort of interventional studies in the future to try and really understand how to unwrap these things. Absolutely. I'm looking forward to some big studies. I think you've nailed it. Yeah, very good. Brilliant. Well, I'm hungry,

Starting point is 00:59:01 so I'm going to go for a snack now. My stomach's been rumbling the last 10 minutes. I'm ready for my snack. I'm going to wait till tomorrow. Thank you all very much indeed. Thank you. It's been fun doing it in person. It's been fun. Thank you, Sarah and Tim, for joining me on Zoe's Science and Nutrition Today. If based on today's conversation, you'd actually like to understand what are the right snacks for your body, then you may want to try Zoe's Personalized Nutrition Program.

Starting point is 00:59:26 The idea is by following this, you can feel more energetic, improve your gut health, and actually reduce your risk of long-term disease. As a member, you start by doing an at-home test so we can understand how your body actually responds to the foods you eat. And then we take all of this data and we combine it with all the latest science from Tim and Sarah and all the other scientists we've worked with

Starting point is 00:59:47 to build a personalized nutrition program for you. Your membership then comes with recommendations, not just on meals, but of course on the snacks you should eat, access to our nutrition coaches

Starting point is 00:59:57 and scientifically backed nutrition advice on how you should eat for your best health. If you're interested in learning more about Zoe, you can head to joinzoe.com slash podcast and get 10% off your purchase. As always,

Starting point is 01:00:10 I'm your host, Jonathan Wolfe. Zoe Science and Nutrition is produced by Rich Willem, with support from Sharon Fedder, Yeleth Ewing-Martin, and Alex Jones here at Zoe. See you next time.

ZOE Science & Nutrition - How snacking impacts your health

There aren't comments yet for this episode. Click on any sentence in the transcript to leave a comment.