ZOE Science & Nutrition - Recap: Is snacking really that bad? | Prof Tim Spector and Prof Sarah Berry

Episode Date: August 27, 2024

You’ve probably heard conflicting advice on how often to eat. I know I have. And have you ever wondered about the evidence behind eating 3 meals a day? Could 2, or 5 meals actually be healthier? Professors Tim Spector and Sarah Berry join me to share some unexpected insights and practical advice to help you base your snacking habits in the latest science. Learn how your body responds to food 👉 zoe.com/podcast for 10% off 🌱 Try our new plant based wholefood supplement - Daily30+ *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system 📚 Books from our ZOE Scientists: Food For Life by Prof. Tim Spector Every Body Should Know This by Dr Federica Amati Free resources from ZOE: Live Healthier: Top 10 Tips From ZOE Science & Nutrition  Gut Guide - for a healthier microbiome in weeks Have feedback or a topic you'd like us to cover? Let us know here Listen to the full episode here

Hello, and welcome to Zoe Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today, we're discussing how snacking impacts your health. You've probably heard conflicting advice on how often to eat. I know I have. And if you ever wondered about the evidence behind eating three meals a day, could two or five meals actually be healthier? Professors Tim Spector and Sarah Berry join me to share some unexpected insights and practical advice to help you base your snacking habits in the latest science. What's really interesting is that over the last 10 years or so, there's been lots of

randomized controlled 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 what we call cardiometabolic health outcomes. So factors related to cardiovascular disease or type 2 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. 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 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 on healthy 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 you know between say lunch and dinner if you have snacks and they're healthy 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 uh whereas snacking events during the day sarah's you's spot on that that's exactly right. Thank you, Tim. Can we 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. So you were saying that one part of this is frequency. So how often you eat?

What else affects? 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. 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 six or very late after 9pm, which actually 35% 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 Gogglebox, everyone's watching TV on their sofa and they've got plates of sandwiches and cakes with their mugs 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 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, 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, because I think I've just had a lot of personal experience about, you know, sort of the way that by swapping 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 no 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 you know i went to spain over the holidays recently and they eat incredibly late. Do we know, 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 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'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 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, woke up the next morning lots more hungry than the people that were having it later in the day, despite eating late in the evening, 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, 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 uh between your overnight meals before you ingest anything 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 it's, you know, 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 and it helps our metabolism That's our energy management system. So the more we do that, the 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. 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 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 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, 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 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. So I thought, well, I'm gonna do this intermittent fasting. I can't eat anything until midday. 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 you know so so i think that's really interesting i would have starved in those 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 between the time when you're

going to have your first meal and your last meal, 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. Is this right? 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 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. What they found was, 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 less hungry. And so they didn't go on to eat quite as much of the next meal as the people that had eaten a really large single meal earlier in the day.

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