ZOE Science & Nutrition - How to improve blood sugar control with exercise

Starting point is 00:00:00 Welcome to Zoe, Science and Nutrition, where world-leading scientists explain how their research can improve your health. Blood sugar. It's one of the rare areas in nutrition where everyone agrees we should avoid big peaks and dips. Repeated spikes can cause inflammation, accelerate aging, and increase our risk of type 2 diabetes. Blood sugar crashes can make us feel moody and tired and even make us hungrier. We can control our blood sugar through what and how we eat, but there's something else affecting our blood sugar. Physical activity. Exercise has a profound effect on our blood sugar response and can help us maintain better control of our blood sugar for a healthier life. Today I'm joined by Dr. Javier Gonzalez, Associate Professor of Human Physiology at

Starting point is 00:01:01 the University of Bath, whose research focuses on understanding the interaction between diet and exercise. I'm also joined by nutritional scientist and Zoe regular Sarah Berry. She's one of the world's leading researchers into how food affects our blood sugar. Sarah says she has a vested interest in today's topic, as 2023 is the year Sarah plans to start exercising regularly. In this episode, we find out how exercise affects our blood sugar response, how much exercise we need to benefit, and the surprising effect exercise may have on our blood sugar, even while fasting. Javier and Sarah, thank you so much for joining me today.

Starting point is 00:01:45 Why don't we start, as we always do, do with a quick fire round of questions from our listeners and the rules are the same as always. Please a yes, a no, or if you absolutely have to, a one sentence answer, but no more than one sentence, which we always know is difficult for a scientist, have you? Are you ready to go? Yes. Yes. Brilliant. All right. Starting with Javier, can exercising improve my blood sugar control? Yes. Is it common to have a blood sugar crash after exercising? No. If I exercise before breakfast, will that put too much stress on my body and potentially cause inflammation? No.

Starting point is 00:02:28 Should I therefore exercise before breakfast? It depends. You are allowed that sometimes. I know this is a tricky one. If you can see Javier, you can see he's sweating with like, you're asking me to make this so simple. It just doesn't seem right. All right. Can exercise affect fats in your blood like cholesterol? Yes. All right. And Sarah, one for you. Lots of snacks are sold as energy boosts to get us through the day. Do they help you with your blood sugar? It depends.

Starting point is 00:02:54 So Javier, Jade on social wants to know if it's true that a 30 minute walk is as good as 30 minute cardio for menopausal women. Well, as always, it depends on a variety of factors. I'm assuming that with cardio, we're talking about more intense exercise. And on that basis, a 30-minute walk probably isn't as good as 30 minutes of cardio for overall health effects, especially as we're aging, we need to maintain muscle mass. We need to try and maintain our bone health as well. And that's where more vigorous intensity exercise can really provide a benefit.

Starting point is 00:03:30 But having said that, 30 minutes of walking has a whole load of health benefits, especially for things like blood sugar control, which we can get into later on. Brilliant. Well, why don't we get into all of that? And what I suggest is maybe we could just start with what is blood sugar and why should we care about it? Yeah. So blood sugar is a main fuel providing, especially our brain with fuel throughout the day. And so when we're not eating, our brain is still using fuel and we need to provide it with that sugar in some form. So when we wake up in the morning, most of that sugar is coming from our liver. Our liver is breaking down its stores of sugar and it's also producing sugar as well, providing the brain with

Starting point is 00:04:15 that important fuel. And then with other types of activities that we do throughout the day, things like our muscles will also need some of that sugar as fuel. It sounds pretty obvious, therefore it's very important. We all know if your brain stops working, everything else happens, but there's so many different processes in our bodies. Why do we care about blood sugar particularly? What is it that makes it such a big focus of your study, for example? Yeah, it's probably because we need to keep our blood sugar within a relatively tight range to maintain health. Too low and our brain doesn't have enough fuel and we can end up going into a coma. Whereas if we have too much blood sugar, then that can cause damage to our blood vessels. So we need to keep

Starting point is 00:04:58 it in a tight range. And for that reason, at least in most healthy people, we have a load of physiological processes that aim to keep that blood sugar within that tight range. And maybe you could actually talk through that. Maybe imagine like, you know, I wake up in the morning, or maybe even before I wake up, you just talk me through what happens during a typical day in terms of this sort of blood sugar control you're talking about. Yeah, when you wake up first thing in the morning, you haven't had anything to eat for probably 10 to 12 hours. Your brain is still using glucose. And at that time, you've probably got about five grams of sugar in your blood. Your brain is using about that amount per hour and other tissues are using sugar up as well. So if you weren't producing any sugar,

Starting point is 00:05:44 you'd run out of sugar in your bloodstream, certainly within an hour, probably within about 30 minutes. And so what happens is our liver is breaking down this stored sugar, releasing it into the bloodstream to provide that sugar for the brain and the other tissues. And it's also producing sugar from things like proteins and other sources. That's when you haven't eaten. The next thing you might do in the day is maybe have some breakfast. So that breakfast might have carbohydrate in it. And so now we've got sugar appearing from our intestine as we've digested and absorbed that carbohydrate. Now we've got an extra source of sugar in the bloodstream. And now the challenge

Starting point is 00:06:23 is actually preventing the sugar from rising too high. So one of the first things to happen is that we'll release a hormone called insulin, and that insulin will cause our liver and our muscle to respond to try to buffer the glucose, the blood sugar, so it doesn't rise too high. So what happens with the liver is that it goes from producing glucose to starting to store glucose. And the muscle also starts to take up sugar out of the bloodstream. It does it slightly more slowly than the liver at first, but then it speeds up and actually quite a lot of the sugar from the meal that you eat will end up in your muscle stored as something called glycogen in the storage form of sugar.

Starting point is 00:07:09 And Javier, I want to stop there for a minute just because this is a complicated picture that you're describing. And I know you're simplifying it for us, but you're already describing how much is going on in our body, right? I just thought I woke up, like walked downstairs, didn't go into a coma, which I normally, you know, I think of as like, I never thought about that as a success, but I can now see, you know, every half hour, if I don't go into a coma, like my body's doing a great job. There's a lot that's going on here, isn't there? In order just to make sure you've got this regular amount of sugar in your body. Why is the food such an important part of this story?

Starting point is 00:07:43 And why do people worry so much and talk so much about blood sugar? Because you might say, hey, yeah, there's also all sorts of clever things going on inside my brain or whatever, but we never think or talk about them. Like what is going on here that causes us to, you know, you to want to study it and us to really think about this being important for how we might choose to behave? Yeah, there's probably two main reasons why it's important to understand blood sugar. One is that it gives insight into our health. So if we compare people's responses to the same meal, the different blood sugar responses can tell us, are their muscles working well? Is their liver working well? And then secondly, that food has

Starting point is 00:08:23 a direct impact on our blood sugar levels. So a meal that has a lot of carbohydrate in it, particularly carbohydrates that are rapidly digested, will have a big increase, a big impact on our blood sugar level. And Javier, just to make sure everyone follows this, this is because basically your body takes those carbohydrates, which might be like bread or pasta or rice, and it's actually turning it into blood sugar, right? Exactly. Yeah. When we eat a meal containing any form of carbohydrate, it will ultimately get broken down and converted into glucose if it's not glucose already, which is essentially sugar and appears in our blood as sugar.

Starting point is 00:09:01 And Javier, I think lots of people are listening to this and saying, okay, this is all very complicated. But I think the thing that you said that they're going to be listening to is like, what really matters is how well do I control this? So I think you're saying, if I can manage to keep this in a sort of fairly tightly controlled band, then everything is good. And they're probably saying, well, so what happens if I can't? And why is that? So I think we had a lot of questions from people saying, you know, does my ability to control my blood sugar change with my age, with menopause? What's the reality about this? Yeah, so it certainly does change over our lifespan. And one of the main terms that people might hear is something called insulin sensitivity. That is basically how well our body is responding to that hormone insulin, which is the key hormone for keeping our blood sugar under control.

Starting point is 00:09:56 There are two key phases in our life where we all become slightly more insulin resistant, less sensitive to that hormone insulin. And that's in adolescence and also throughout menopause. And all of us, as we age, will tend to become less insulin sensitive. In adolescence, it's largely because of the growth hormone that you get as you're growing in adolescence that can reduce our insulin sensitivity. It's a normal process of adolescence. As we go through menopause, then the hormonal changes there can also reduce our insulin sensitivity. So they might be key periods of our life where we might pay particular attention to blood sugar control, but all of us as we age should probably pay more

Starting point is 00:10:42 attention also. And Javier, we've got some great research from our ZOE predict studies on the blood sugar changes that happen between males and females as we age and also whether you're pre, peri or post menopause, which fits in with exactly what you're saying. So what we see is that at most ages, men have a worse blood sugar response to a standard meal compared to females. Then females, we hit the menopause and bang, it goes up to the level of men and actually worse than the level of men. And we actually published some research on this recently where we also were able to look at postmenopausal women and match them according to age. So we could have a look if you're postmenopausal or premenopausal, but of a similar age, do you still have a worse blood sugar response if you're postmenopausal compared to

Starting point is 00:11:39 someone of a similar age as premenopausal? So that's taking away the impact of age and only looking at the impact of oestrogen. And we still saw a really big difference in people's blood sugar control with those that were postmenopausal having far worse blood sugar control. So higher blood sugar responses to a standard meal compared to the premenopausal women. So Sarah has depressed us with the arrow of time and the... You're okay. Look, you're not a 45-year-old woman that's about to see that big spike soon, Jonathan. That's true. I'm already over a 45-year-old man who's been worse than you throughout my life to this point and has one of the worst blood sugar controls of anyone we've measured. But I appreciate that. And I agree. Where I was thinking of going with this, though, Javier, it's like your big area of research is actually all about exercise and how

Starting point is 00:12:29 this fits with blood sugar. And I think that's exciting because it's talking about things that you can do rather than just what happens to us as we age. Could you explain at a high level, so we can follow along, hopefully, how exercise affects how our body is dealing with blood sugar yeah and it's probably worth considering exercise in three main phases so one is what happens to our blood sugars during exercise what happens to our blood sugars immediately after exercise and then what happens if we've done training so if you've done months and months of exercise how does that affect our body in a way that we can control our blood sugar levels so if we start with the first one during exercise when we start any form of exercise our muscles are increasing

Starting point is 00:13:17 the amount of energy that they're using so they need energy to continue the exercise and a large amount of that energy will be coming from the sugar in the blood so the the muscles will start taking up more sugar out of the bloodstream and so logically you can immediately imagine that that's going to help control our blood sugar levels it's a slightly more complicated picture in that our liver will also start producing more sugar to try and provide more fuel to the muscle but if we do that bout of exercise after we've eaten a meal then compared to just resting it will tend to lower our blood sugar levels quite quite dramatically actually so it's quite a potent effect. And actually, there's some really interesting recent research showing that really light intensity exercise, basically fidgeting and moving your knee up and down.

Starting point is 00:14:12 They were calling it soleus press-ups, which is the muscle in our calves. Just if you imagine bobbing your knee up and down, doing that after eating a meal could drastically lower the blood sugar response about 30% after a meal. So it can be quite a profound effect. By 30% just by like fidgeting my knees around? Yeah. Yeah. I always, unfortunately, eat my food whilst during Zoom meetings, which is unfortunate for Jonathan, who's normally having to watch me munch away. And then I sit there feeling like, oh my gosh, I'm always telling everyone go for a walk after you've eaten. But what you're telling me, Javier, is that I can just sit here and fidget, which is what I'm doing now, fidget my legs, and that's going to do the job. Exactly.

Starting point is 00:14:56 Well, I'm so glad I joined this podcast. That's phenomenal. And I am a terrible fidget. So I know, Javier, you've talked a bit about this to me previously, and I have wondered if that is an important part of how I appear to always be so hungry. So if I was to go for a walk, as we often recommend people to do after having their lunch, or I was to sit at my desk and fidget for however long, would that fidgeting have the same favourable effect in lowering my blood glucose response as me going on the walk? Forget the other aspects of the healthiness of going on the walk just for the blood glucose response. The walk is probably going to have a larger effect because you've got more muscle groups that are being recruited during the walking. And studies

Starting point is 00:15:45 have shown just two minutes of walking every 20 minutes throughout the day lowers your blood sugar levels by about 50%, whereas this fidgeting of the knee lowers it by about 30%. So it's hugely effective, but the more muscle groups that you activate, the more effective it seems to be. So basically every 20 minutes, you either go to the toilet or get up from your desk and go and make a cup of tea and you're on to a winner. Yeah, yeah.

Starting point is 00:16:12 And Javier, I think you said there was another level of exercise. You've got the fidgeting, you've got going for a walk. There's more beyond this? If you were to do, say, a jog or a run and increase that intensity of exercise, then you get some other changes happening as well. So you start to use up the stores of carbohydrate in your muscle, and that will have effects that we can come on to after exercise.

Starting point is 00:16:36 But it also produces an adrenaline response. So you get that adrenaline hit, and you can sometimes actually see an increase in blood sugar levels during exercise because of that adrenaline hit. And you can sometimes actually see an increase in blood sugar levels during exercise because of that adrenaline hit. It makes our liver produce more sugar for our muscle to use as a fuel. So it's a normal response that people shouldn't necessarily be afraid of, but can be expected with high intensity exercise. And actually, I was going to ask a bit about the difference between what goes on in like a short burst of exercise. So let's say, you know, I was going to ask a bit about the difference between what goes on in a short burst of exercise. So let's say I just took my daughter to school this morning and I walked there and then I came back and then I sat down in my chair versus something that's going on for longer

Starting point is 00:17:17 because you were talking about the way that there's only a limited amount of sugar in my blood. And even if I was eating some food, you know, there's only so much that's coming in, I guess, every few minutes. So what happens in those two situations? Yeah. So with your kind of lower intensity walking and that kind of thing, the muscle is mainly using up the sugars from the blood. Whereas when you increase the intensity, it uses more of the fuels that are within the muscle itself. So it uses up its own carbohydrate store. And that will have more of an impact then on your blood sugar after exercise than during

Starting point is 00:17:51 the exercise itself. And so just to make sure that I've got this, your body actually has lots of different fuel tanks. So, you know, if I think about this as like a car, we only have one place with the fuel. Now you've mentioned there's like little fuel tanks in our muscles, but you also mentioned that our liver is like a big fuel tank because you talked about the way that that is providing blood sugar. And then also if I eat food, it's either rapidly or slowly sort of coming out of my gut and into my bloodstream. Are there even more or is that- So the carbohydrates, the sugars that we have

Starting point is 00:18:26 available are in those three main sources, as you say. In our muscles is actually where we store most of our sugar. We have a smaller store in the liver. And then if we eat some sugars, then that's the third way we can get sugars available. Oh, that's brilliant. I'm doing the Zoe program right at the moment. And as part of that, I'm doing an intermittent fast for the second week, which is a sort of a study that we put on the top. So actually it's the first podcast I've ever done hungry. And I don't know if you can hear my stomach rumbling. I'm very bad at intermittent fasting, as Sarah knows, but it is interesting that, you know, my blood sugar is basically completely flat, you know, from about sometime,

Starting point is 00:19:04 like about two in the mornings. It takes a while after dinner and then basically flat. Interestingly, it's still flat when I went on this walk. And then actually it has gone up a bit afterwards as I've come back. It's been snowing today. It was quite a hard work pushing my daughter there and back again. And so it's fascinating that all of that blood sugar is nothing to do with my food. It's all to do with what's going on with, I guess, these other systems. Javier, can you talk me through a bit, I guess, how does it stay so flat like this? And I've done a bit of exercise without fasting. Is that, you were saying before, that might be a good thing or it might not?

Starting point is 00:19:41 How do I think about that? And J have it to add to that as well would be great to understand a little bit about how some people even when they haven't eaten food have changes in their blood sugar so you see some a lot of people experience a small peak when they wake up in the morning in their blood sugar so i wonder if you can add that to jonathan's uh answer as well yeah yeah sure sure. So just starting with Jonathan there, if you were to fast, then one of the main ways in which you're able to still maintain your blood sugar level in that healthy range is because your muscle will start to switch from using carbohydrate or sugars as the fuel to actually using fat as a fuel. So it's no longer needing to take up as much sugar out of the bloodstream. The brain still needs to use sugars, but the liver is providing those sugars for the brain. And if you fast for a very long time, then your liver can actually produce a different fuel for the brain known as ketones, but probably a separate topic. I definitely won't fast that long. I'm a miserable at fasting. I'm hungry. As soon

Starting point is 00:20:48 as this podcast is over, I'm going to eat a ridiculous amount of food and I see an enormous blood sugar spike because the whole point is you're not supposed to just squeeze breakfast and lunch into one meal, but I always do that. So I know what I'm going to do. I'm going to have like this enormous meal afterwards. So my brain is all right. It can keep running on glucose, Javier, is I think the conclusion. Well, Jonathan's one of those rare adults that really gets hangry. So any parents out there know what it's like when your kids are having too much of a fast, they get hangry. Having worked with Jonathan for many years, as wonderful as he is, he does suffer from serious cases of hunger. I wouldn't have come on the podcast if I knew you were intermittent fasting, Jonathan, today. No, I think you're quite right. I apologize in advance to all the listeners for

Starting point is 00:21:35 the fact that I'm clearly going to be in a worse mood than normal. You're being your normal, charming self. I'm completely the same as well. I do prefer to eat more frequently. But when you then did your walk and you see a spike in blood sugar after exercise, perhaps what might have been going on there is when you do the exercise, you get this adrenaline release and your liver is producing more sugar. Then you stop your exercise and your muscle no longer needs that extra sugar, but the liver takes a little bit of time to reset. It's still producing that sugar. And so you can get a rise in the blood sugar level. And it's a similar thing that might happen when you first wake up in the morning, or it might also happen if you undergo a stressful situation, but you're

Starting point is 00:22:20 not being physically active. So say doing a podcast when you're sitting still and you might feel a little bit nervous, then you can get a spike of adrenaline that might cause your liver to produce a bit more sugar than you actually need at that particular time. And so you get a rise in your blood sugar level. And it might be one of the reasons why too much stress is a bad thing for our metabolic health. And while we're talking on this, I remember on our previous podcast, where you're talking really primarily about exercise, you said that you've been doing this study where you'd said actually fasting

Starting point is 00:22:53 and then doing exercise actually could be beneficial. And I thought it sounded crazy, but I did want to report back that I have tried it now. And I was terrified basically that I would go and do a gym session without any food and I would just fall over and it wouldn't work. And immensely to my surprise, it was completely fine. And actually, I guess this is back to your story about actually you've got all of these reserves in your muscles. It was fine and I performed completely okay. And I'd always had this mind, I am someone who's proud of poor blood sugar control. I do tend to get these dips as we've discovered with our more recent research that actually I was able to function. It worked because I was sort of

Starting point is 00:23:34 thinking, ah, but I wouldn't be able to do as well as if I'd had breakfast before. Because my mother definitely was, you know, you can't leave the house without having a proper breakfast, right? That was one of the iron rules in the house. I think my mother has generally been right over most things. I was like, that must be true. But I finally found something where I think she was wrong because actually it worked. And, you know, Javier is nodding saying this is sort of obvious, but I think most people aren't aware of this. Yeah, absolutely. And I'm glad you found some benefits. Certainly our own research has found, and we're getting onto that longer term adaptation to exercise. So if you were to do your exercise regularly, then that can have some beneficial changes in our metabolism that means we can better control our blood sugar level.

Starting point is 00:24:22 And some of our research has shown that that improvement is even greater if you do your exercise regularly in that fasted state or just before having breakfast, really. And a large part of that, we think, is because the muscles themselves are adapting more to the exercise when you do it in that fasted state. And Javier, something that we're particularly interested in, as you know, Zoe, is personalization around how we might want to give one piece of advice to someone and different advice to someone else. And there's some work I think you've done in the past looking at how timing of exercise in relation to timing of food may impact your metabolic health. And if I remember correctly, you saw differences between males and females that might suggest we

Starting point is 00:25:12 should recommend different timings based on that. I wonder if you could tell us a little bit about that work. Yeah. So the only study we've done specifically on the meal timing and exercise for blood sugar control was in a very small group of men. So we do seem to think that at least in men, doing that exercise in a fasted state seems to have this benefit. Other work we've done where we've looked at the differences in metabolism of men and women and of people of just a wide range of different demographics, we find huge differences in their ability to burn fat as a fuel. And so we link those two together because we think that our ability to use fat as a fuel has some link with our ability to control our blood sugar levels. And so because we see large differences in people's ability to use fat as a fuel, we think there could be individual differences in the response to doing

Starting point is 00:26:12 your exercise before or after breakfast. Now, the actual study on that we've got ongoing at the moment to see do men or women benefit more from this type of exercise. So hopefully we'll have an answer in the next year or so. But for now, we speculate that there could be differences, but yeah, actively researching it. Amazing. We look forward to hearing. Now, one of the things, as you know, we really like to do on this podcast is make sure we can go from sort of this cutting edge research to stuff that's actually actionable. And I think lots of people will be listening to this and saying, okay, so I understand therefore that exercise is a very important component of how I might be able to better

Starting point is 00:26:53 control my blood sugar. And some people may know that they really need to worry about that because maybe they've been told they have prediabetes or diabetes, or maybe they've done something like Zoe where they've been told they have pre-diabetes or diabetes, or maybe they've done something like Zoe where they've got this. I think what they want to know then, Javier, is, okay, help me to understand really how often should I exercise? How intensely do I need to exercise? And then actually we had lots of questions about specific types of exercise, and I may come onto those, but maybe you could just sort of give some advice to help people to think about what they should do if this is something they'd really like to try and improve.

Starting point is 00:27:27 Yeah, my overarching advice would be do something that you enjoy and that you will do regularly. And there is probably an element of the personalization here as well, where some people might enjoy certain forms of exercise and might even benefit from certain forms of exercise more than others. And in a similar vein, I think the first point I'd make is if you are only able to do low intensity activity for whatever reason, then a good time to do that is after you've had a meal to lower that blood sugar level after each meal. And that's where low intensity, even the fidgeting that we discussed earlier, can have quite a profound impact. And Javier, just before we move off, just to help

Starting point is 00:28:09 people understand, what is low intensity exercise? I'm guessing fidgeting most of the time, it's probably a bit more than that. What could I be doing if I wanted to be doing that? Yeah, fidgeting, walking around, household chores count, gardening, anything like that, where you're moving around, but you're not really getting out of breath. Got it. So what is then the level beyond which I could see you clearly want us to achieve while recognizing obviously maybe not everybody can? Exactly. Yeah. So the higher intensity activities, which is when you start to become out of breath and you struggle to string sentences together that's

Starting point is 00:28:46 where you can get some of these longer lasting adaptations where your muscles and your liver and other aspects of your body have changed over time and you've got better blood sugar control in the long term so the the lower intensity activities have immediate effects whereas the higher intensity activities can actually change our physiology so that we control our blood sugar levels in the long term. What about sort of, people ask a lot of questions always about this difference between things that seem that they're high intensity, so that, you know, things that are heavy versus things that are like running, which also make you breathless,

Starting point is 00:29:26 but don't have that same sort of weight. People often talk about like cardio versus that. Does it matter for this topic around blood sugar control? Not really. They do have slightly different effects during the exercise. But if we think about you do your bout of exercise and then you have your meals later on in the day, they then act quite similarly. And what they do is that when you do your bout of exercise and then you have your meals later on in the day, they then act quite similarly. And what they do is that when you do your bout of exercise, your muscles are taking up more sugar out of the bloodstream, independent of insulin and all these other hormones. The exercise itself means that it's taking up more sugar out of the bloodstream. But then a second component to that is that the muscle's sensitivity to insulin is heightened

Starting point is 00:30:07 over the next day to two days. So it's a two-pronged effect when you do this higher intensity exercise. You increase the sugar uptake into the muscle independent of insulin, but you also increase the sensitivity of the muscle to insulin. So that's very cool. So you're saying it's not just that I get a benefit right now, but actually this is having sort of this longer term effect as well. Exactly. And some studies have shown with very vigorous exercise, so 45 minutes of pretty much running as hard as people could, Their blood sugar control was improved for up to three days afterwards. So the more intense the exercise, the longer that benefit can last. And do we understand why this is happening both in the next few days and even sort of

Starting point is 00:30:58 permanently? Like what is going on through the exercise that actually means, because you know, anything that is a long-term benefit sounds great, right? Rather than having to sort of do it, start from the beginning and feel, I always love these stories that you can make permanent improvements, despite the fact that maybe you're not 21 anymore. Yeah. Yeah. Well, there's two main ways in which the immediate effects of exercise work. One is we increase the blood flow to the muscle. So we're delivering that sugar to the muscle so it has more to take up. And a second is that we've reduced that store of sugar within the muscle. So that fuel tank is low and that is a stimulus for the muscle to take up more sugar out of the bloodstream and store it and replenish that fuel tank. The longer term changes are mainly to do with,

Starting point is 00:31:47 it's a bit like a door that allows entry of the sugar into the muscle. It's known as a glucose transporter. The number of those that we have in the muscle can increase when we do our exercise training. And so we have a greater capacity to allow the sugar into the muscle. More of those transporters, more doors to allow the sugar to enter the muscle. And Javier, for someone like myself who is very busy with work and kids and doesn't particularly enjoy exercise, is there any such thing as a silver bullet? Now, I always say there isn't when it comes to nutrition, but you often see on the TV new shows coming out saying, oh, you know, do 90 seconds or three minutes a day of HIIT and that's all you need to do. What's your opinion on the cheat sheet that I could do in my busy life? Yeah, I think rather than thinking of only exercise, I think every form of physical

Starting point is 00:32:43 activity that we incorporate in our life, we should remember can contribute to our health. So I think people get put off by exercise because it feels like a chore. You have to do it for an hour, go to the gym at this time of day. Whereas by taking an active commute to work or just going for a walk with friends and doing some of those your daily activities but making sure that you're moving whilst you're doing them if you can then that can integrate more easily into your life and it doesn't feel like you're doing a chore and it doesn't feel like exercise but whether there's a silver bullet yeah that's what I want yeah that's what I want to live with I know that after every

Starting point is 00:33:26 meal I'm gonna sit twitching my legs that's the biggest take-home for me from this podcast but I would like to know is there anything I can do in five minutes each day alongside the fact I walk the kids to school etc is there something I can do in a five minute break between meetings um I'd I'd be lying if there was, sorry. Sarah, it's a great question, but it sounds like Javier sadly is just going to tell us the truth rather than sell us a story we'd like to hear. Well, look, we've got two great tips. We've got the tip every 20 minutes, I'm going to run up and down the stairs because I work in the loft. So I've got two floors of stairs to run up and down to get my cup of tea. I'm going to twitch my legs every time after I eat. I think if I start with those

Starting point is 00:34:10 two, it's all about these micro changes that we often talk about. So that's two micro changes that actually aren't going to annoy me too much. Sounds great, Sarah. So before maybe wrapping up, I think with Javier, you may already be stealing some of his tips, Sarah, Javier's tips. I would love to talk a little bit about the blood fats, which we touched on right at the beginning. So as well as blood sugar, there are also these fats in our blood. And I think cholesterol is the one that everybody tends to know about. Why does that matter? And does exercise have any impact here? Because we tend to always just think and talk about the blood sugar. But I think you said right at the beginning that actually exercise also has an effect here yeah it does and i quite like to compare this to diet because one of the ways in which we might lower our blood sugar

Starting point is 00:34:57 levels is by reducing our carbohydrate intake but if it's quite often replaced by fat intake. And the more fat you have in a meal, the higher the levels of fat in the blood after the meal. The more carbohydrate in the meal, sometimes the higher the blood sugar levels after the meal. So with diet, there's sometimes a trade-off. Whereas with exercise, exercise can lower both the levels of blood sugar and the levels of blood fat after a meal but it does happen in very different ways and over different time frames so can you explain a little bit what's going on with the fats and explain a bit what they are and you know i mean we've got sarah one of our world experts here to maybe just help us to unpick this yeah i mean do chip in sarah because you are the expert on this. I guess if I

Starting point is 00:35:45 just start and you can correct me, is there are multiple types of fat in the blood, whereas sugar is mainly circulating as a specific thing called glucose. The fats come in different forms. And the other difference with sugars is that fats don't dissolve in water very well. So in our blood, they need to be carried, attached to other things. So they're normally within proteins or bound to other proteins, and that makes them dissolve in the blood and be transported. And one of the main ones is called the triglyceride. It's a type of fat in the blood that is released from the liver when we're not eating and goes to the other tissues, to the fat tissue to be stored and also to the muscle to provide a fuel there. So Jonathan, what we know is when we consume fat in a meal, the fat results in an

Starting point is 00:36:39 increase in triglycerides that circulate in the blood, just like when we consume a carbohydrate-rich meal, it results in an increase in blood sugar or blood glucose, as we call it. But it's quite a different pattern of response. Whilst the blood sugar from the carbohydrate peaks very quickly, so you get a peak around 30 minutes in the blood and returns to baseline around two hours, with the fat from the meal, it causes an increase in blood fat about four to five hours after you consume the meal it doesn't return to baseline fasting levels until about eight hours after you consume the meal now given that we consume multiple meals throughout the day what this then means is that you spend most of your time in what we call a postprandial lipemic state now i know you don't

Starting point is 00:37:23 like me using complicated words like that, so I'll explain what I mean. So what this means is that you are spending your time in this post-meal elevated fat state. So let's say you have your last meal at eight in the evening and your blood fat levels don't return to fasting until eight hours later. That means normally for lots of people, it's only between about four in the morning until about whenever you have your breakfast, like let's say eight in the morning, that your blood fat levels are ever at this kind of fasting level. And we know that if you have really excessive blood fat responses, then it sets off a cascade of unfavorable effects such as oxidative stress and inflammation.

Starting point is 00:38:06 And this is where it's really great that there are strategies that we can bring into play that will allow us still to consume a fat-containing meal without having any unfavorable health effects. Exercise is one of them, like Javier said, but also you can add other foods and nutrients to your meal that can kind of put out this unfavorable effect, be like a bit of a firefighter dampening this inflammation. So we know that different components in the meals like polyphenols, which are chemicals from very colorful fruits and vegetables can dampen this fire, but also exercise. And so Sarah, there will be people listening who probably say, you know, I've been to the doctor and he's told me I've got high cholesterol and I've got too much of the bad sorts of

Starting point is 00:38:55 fats in my blood. So they'll suddenly have perked up and there'll be others who don't really know because actually this postprandial effect, you know, what happens after you eat, you would only discover, for example, if you do one of the Zoe tests that we built in because we think it's very important. I think for today, what would be fascinating is to understand, okay, how could exercise play into this? Because I think in general, my dad was told about this 40 years ago and really advised all about diet. I mean, can exercise play any role on this as you described it doing on blood sugar? Yeah, it has just as much an impact on the levels of fat in the blood as it does with sugar. And it is mainly what you've done the day before though. So whereas

Starting point is 00:39:38 with blood sugar control, it has quite an immediate effect. With the blood fat levels, what you did yesterday in terms of exercise will affect your responses today. So the peak effect happens about eight hours after the last bout of exercise. Again, there are effects of intensity and of the total amount of exercise that you do. Just before I explain the effect, it's probably also worth noting that even if exercise doesn't affect the level of fat in the blood in a similar way to Sarah mentioned there with polyphenols, regular exercise can increase our natural antioxidant capacity. So it's a bit like you've consumed a load more fruit and vegetables, your exercise increases your body's natural antioxidant capacity and so for the same

Starting point is 00:40:26 level of fat in the blood you're probably protected against some of the negative effects but exercise also lowers that level yeah and that's just how the polyphenols work as well um have you so the polyphenols for example don't lower the amount of fat, but they put out that fire in the same way that the exercise might. Exactly. Yeah. And then exercise can also lower that level of fat in the blood. It does require a reasonable amount of exercise. So if you're doing low intensity, like a walk, then it needs to be about 45 minutes to an hour to have at least the effect that is seen in studies. And it can lower it by a substantial amount, by up to 50% the next day. By 50%. Okay. That's enormous. You're not just talking about like a little effect. That's an

Starting point is 00:41:16 enormous effect. It's huge. And it seems to be a larger effect in the people who need it the most. So the people who show the biggest blood fat response under normal conditions show the biggest reduction when they've done their exercise the day before. So quite a useful effect. And just, you were saying they need to do a longer walk, but actually if I went for a walk for 45 to 60 minutes, that could actually have this huge impact on how I'm dealing with my fats the next day. Yeah, exactly. And you might think, well, is it because people are in a calorie deficit? They've done some exercise, they're now in a calorie deficit. And so is that the only reason that they've got this better response the

Starting point is 00:41:57 next day? But we know that that isn't the case because when that's being controlled for in studies, the calorie deficit has some effect, but exercise has an even greater effect than just the calorie deficit. So it's acting in more than just the calorie deficit to lower the levels of fat in the blood. Javier, I'm conscious we've covered a lot of ground and I do want to make sure that I've asked you specifically about your sort of three tips. So people listen, we picked up a bunch through this conversation. Imagine someone saying, okay, that's really interesting. I really want to do something that is manageable and actionable. So if you had sort

Starting point is 00:42:35 of three tips for people who want to manage their blood sugar, maybe want to manage their blood fat as well, you know, using exercise, what would you say? Yeah. So I'd say try to do something every day, no matter what it is, would be point number one. I'd say point number two is if that something can only be relatively low intensity, then try to do that after you've eaten a meal. And then point three would be if you're able to do higher intensity activity, then you should be able to get some longer lasting adaptations. Brilliant, Javier. Thank you very much. I would like to try and do a sort of summary if I can, and we've gone in a lot of different places, so bear with me. And I've got two different scientists

Starting point is 00:43:22 who are going to keep me on this today. So one thing I heard is regular exercise is like eating loads of fruit and veg, which I love as an analogy. We heard, I think, why blood sugar control is important because we need to sort of keep it within a reasonable band and that actually you can change the way you're managing your blood sugar with a surprisingly low amount of intensities. And then I think the last thing you said was actually, you know what, actually exercise can affect the way we deal with fats as well. And probably almost everybody listening is surprised, particularly because you said it sort of has this magic delayed reaction.

Starting point is 00:44:01 So that's extraordinary. So I think the takeaway is, as you said, with your three tips, do something every day, no matter what it is. If it's low intensity exercise, try and do it after a meal, but do try and do higher intensity exercise because it has this long-term effect that can really sustain and support us. Brilliant. Sarah, was there anything else you wanted to add? No, I love it. I'm busy twitching my legs here. Javier, we'll all be twitching our legs for the rest of the day. Thank you so much for coming back on. And we look forward to getting you back again

Starting point is 00:44:32 in the future, maybe talking about some of the results of these new studies. Great. Thank you for having me. Thank you, Javier and Sarah, for joining me on Zoe's Science and Nutrition today. If based on today's conversation, you'd like to understand how your own blood sugar

Starting point is 00:44:46 and blood fat respond to food, then you may want to try Zoe's personalized nutrition program. Your Zoe membership comes with our app and access to our nutrition coaches, so you can learn how to change your diet and health habits and reach your long-term goals. Your personalized nutrition program is based on our scientific research

Starting point is 00:45:05 and the results of your personal at-home test, which includes blood sugar and blood fat measurements. If you're interested in learning more about Zoe, you can head to joinzoe.com slash podcast and get 10% off your purchase. If you enjoyed today's episode, please be sure to subscribe and leave us a review as we love reading your feedback. If this episode left you with questions, please send them in on Instagram or Facebook, and we will try to answer them in a future episode. As always, I'm your host, Jonathan Wolfe. Zoe Science and Nutrition is produced by Fascinate Productions, with support from Sharon Fedder, Yela Hewins-Martin, and Alex Jones here at Zoe. See you next time.

ZOE Science & Nutrition - How to improve blood sugar control with exercise

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