Recap: Exercise and your blood sugar | Prof. Javier Gonzalez
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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 taking control of our blood sugar and we'll dive into a conversation with Professor of Human Physiology, Javier Gonzalez. He explains which exercises can reduce your blood sugar spikes and dips, which will have a positive impact on your long-term health. And don't worry, you don't have to become an Olympic weightlifter to do it.

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 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 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 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. 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 that 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. 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, I

or I was to sit at my desk and fidget for however long

Would that fidgeting have the same favorable 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 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. And Javier, I think you said there was going to be a, there was another level of exercise. You've got the fidgeting, you've got going for 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. 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. 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, 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 because you were talking about the way that there's only like a limited amount of sugar in my blood. And even if I was eating some food, 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 the exercise itself.

And so just to make sure that I've got this, your body actually has lots of different fuel tanks. So 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 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.

flat from about sometime, 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.

you know, 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? Yeah. 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. How do I think about that? Yeah. 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

probably a separate topic. I definitely won't fast that long. I'm a miserable at fasting. I'm hungry. As soon 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 hangover.

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 apologise in advance to all the listeners for 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 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'd been doing this study where you'd said actually fasting 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. 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. 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.

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 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 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?" Maybe you could just 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.

Yeah, my overarching advice would be do something that you enjoy and that you will do regularly. And 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

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 people understand, like 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 can 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 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 lower intensity activities have immediate effects, whereas

Whereas the higher intensity activities can actually change our physiology so that we control our blood sugar levels in the long term. That's it for this week's recap. If you're listening to this, you're already on your way to living healthier through better nutrition. And at Zoe, we're doing everything we can to help you on your way. So we've developed Daily 30, a delicious dietary supplement to add to your meals.

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