Exorcist, or Exercise: what's healthier?

28 January 2014

Live on location at the Cambridge Science Centre, Chris Smith is joined by exercise scientist Dan Gordon, who also holds the world record in tandem cycling, epidemiologist Nita Forouhi, who studies diet, and David Ogilvie, who investigates how our environment can shape our activity. Together they pit their wits against the assembled public as they answer questions like, is watching the Exorcist a replacement for exercise? Plus Dave Ansell and Ginny Smith find the iron on breakfast cereals, measure the vitamin C in carrots, and see how much exercise it takes to work off a Mars bar...

In this episode

02:40 - Exorcist, or Exercise: what's healthier?

Exercise physiologist Dan Gordon explains how he pushes athletes to their limits and answers the audience's questions...

Exorcist, or Exercise: what's healthier?
with Dan Gordon, Anglia Ruskin University

Dave Ansell - To start off with, we've got an experiment which is going to take a while VO2 max measurement through a modern metabolic cart during a graded exercise test on a treadmilland we need a volunteer, somebody who's feeling really energetic this morning, this evening.

Chris Smith - And knows what time of day is, Dave.

Dave - Which I obviously don't. You look like you're very keen, would you like to come up?

Ginny Smith - Can everyone give him a round of applause please? What's your name?

Younas - Younas

Ginny - Younas and where have you come from today? Where do you live?

Younas - Here in Cambridge.

Ginny - In Cambridge, brilliant. Now, we're going to get you to do a little bit of exercise today during the show. So, what do you want him to do, Dave?

Dave - So, what I've got over here is a generator. It's got a handle on it and when you wind the handle, you produce some power. At the moment, that's rigged to just heat up some air, so you're going to be warming up the room for us a bit. But I'm going to work at how much energy you've used in that time and convert that to chocolate bars. Okay, so we're going to get you winding that handle for about 10 minutes and see how many chocolate bars you've burnt. So, do you want to start winding the handle for me, at a speed which you think you can keep up for a while. That's brilliant and yep he's generating about 10, 15 watts of power at the moment which is pretty good going. We'll leave you going Younas for a bit and we'll come back to you later.

Ginny - So, on the screen, I can see a whole load of different numbers but on the left hand side, can you see that it says Mars bars? So, that's how much of a Mars bar he's burning. So, we're going to watch that number and see how many Mars bars he earns in the course of this experiment.

Chris - Are you feeling tired yet?

Younas - No.

Chris - He says no. Give it 10 minutes or so. Well, let's talk to Dan Gordon because you ought to tell people, you have quite a good track record in sport . Tell people what you do.

Dan - That's quite a good pun. Yeah, I was an international track cyclist. I used to race tandems on the velodrome. So, that banked cycling track, but rather than use just one person on a bike, we had two.

Chris - Isn't that cheating?

Dan - Yes, it is slightly. It was quite good, I got to put my feet up on the back and the guy at the front just pedalled really.

Chris - But did you get any records?

Dan - Yeah, I held two world records and I still hold one world record.

Chris - Which one?

Dan - I hold the world record for a kilometre outdoors which has stood since 2003.

Chris - Wow! He's got to get a clap for that, surely. Are you really nervous then every time the Olympics comes around? Are you thinking, "Oh no! They might get my record"?

Dan - No. I get quite anxious actually and particularly in London, a lot of the guys racing, are the guys I used to race with. In fact, the guy I used to ride the tandem is still racing. It's quite hard to be sitting on the other side of the barrier and I've got kind of itchy feet, particularly with about 4 months to go and I did announce to my wife that I thought I might make a comeback. I got shouted down very quickly, but yeah. I'm not worried about the record going. That's what they're there for.

Chris - So, how fast are you going on those bikes?

Dan - For the kilometre time trial, it's about 60 km an hour. So, in old money it's about 43 miles an hour.

Chris - 43 miles an hour. That's amazing, isn't it? Is that what inspired you to become an exercise physiologist or were you already a scientist?

Dan - I was already a scientist at the same time so I was very fortunate that I'd actually retired from athletics. I'm going to show off now, I was an international athlete, I did track and field internationally and I retired, and then saw an advert saying, "Have a go at tandem cycling." So, I was working at the same time. So, it's been quite nice. I've been able to tie my sport with my profession. It's been really quite fulfilling in that sense.

Chris - So, what are you trying to understand when you do experiments on people? What questions are you asking?

Dan - Well, the questions I'm asking in the research is, what limits our ability to use oxygen. If you think what we're doing now, we're all sitting here and especially the young chap who is doing the exercise in the corner, we're having to use oxygen. We are, by definition, what's called aerobic. We use oxygen because oxygen is the primary fuel currency. If you think about the way he's turning that crank, his muscles are lengthening and shortening. What we want to know is what limits that upper ability to do that. There's a point where you cannot provide enough oxygen to meet the demand. There's a huge debate about, is it limited in terms of, it has something to do with the heart? Because if you think what the heart does, it pumps all that oxygenated blood to the muscles and so on, or is it a limitation at the muscle. And so, the experiments that we're doing are really to find out where that limitation sits and is it different for example between somebody who's highly trained, maybe a Bradley Wiggins, to somebody who is untrained or sedentary. Then once we understand the mechanisms, we can then start to actually understand the underlying pathologies and so on behind it.

Chris - Are you the only athlete in your family or does this run in your family?

Dan - The genetic question. My father was a cyclist and that's not why I fell into cycling. I was a typical, "If he does cycling, I'm not going to do cycling." Why would you?  So yeah, he was a cyclist but he had trials with Aston Villa and so on. So, there is kind of a sporting heritage I suppose, yeah.

Chris - Shall we just catch up on how we're doing on the cranking because we've nearly burned 1/500 of a Mars bar?

Ginny - So, how are you feeling?

Younas - Fine

Ginny - Is anything hurting? Are you feeling tired at all?

Younas - A bit.

Ginny - A bit, and where's it feeling tired?

Younas - Here.

Ginny - In your arms. Okay, so your arms are working really, really hard and that's where they're feeling tired.

Dave - How much of a Mars bar does it feel like you've actually worked off so far?

Younas - Two?

Ginny - Two whole Mars bars but in fact, you can see on the screen, it's 0.0027. So, we're nowhere near a Mars bar, let alone two. Why does it feel like you're burning off so much more than you actually are?

Dan - Well, it's a jolly good question in many ways. In this little experiment, you've hit on two major themes. One is, exercise hurts, and that's one of the big reasons that we get significant dropout rates in terms of exercise because actually, there's a huge discomfort with it. The second thing is, unfortunately, genetically, we're not very well built. If you think...

Chris - Thanks very much.

Dan - But apart for some of us anyway. If you think about the way those muscles are lengthening and shortening, and he's got a great pair of guns the way he's turning that. But they're lengthening and shortening and he's providing the oxygen, but what's happening is, for the muscles to lengthen and shorten, you have to use a chemical in the muscle and that chemical is called adenosine triphosphate. Sounds really technical, it's nothing particularly clever. But the key point is, in order use that ATP, we have to get the energy from it and we use water. Simplest process ever, it's hydrolysis. In that process, we generate heat and actually, this is the problem. We actually lose 70% of that energy in the form of heat. So we're actually, only about 30% efficient. So, at some point, the government will tax us because we're producing all this adverse heat. That is why it actually tends to feel harder because actually, we're not mechanically very efficient at doing this, any form of exercise, and particularly, when it's something like that that you're not used to doing.

Chris - So, going back to my question about your family. Does it mean then that some people are better at coping with these situations or have better ways biochemically of preventing this problem?

Dan - Yes. There's a number of camps on this, but there is no doubt, there's a genetic predisposition to being able to do exercise. We know that there are certain genes that seem to describe whether you are an endurance athlete, whether you are maybe a high jumper. But we also are starting to recognise now that there are genes that actually describe why people don't respond to exercise. I'm sure everybody is suddenly going, "Well, this explains everything. That's why I don't go to the gym."  And we're starting to understand - it's about 1 in 10 - that's a quite high number - would potentially be a non-responder to cardiovascular exercise which is the predominant form of exercise we talk about in terms of maintaining a healthy lifestyle. I say to my students, "If you're not an Olympic athlete, it's very simple. Just blame your parents" because that's really the backdrop to everything you do. You're working within the genes that you're given.

Chris - Anyone here got some good genes for exercise? Have we got any athletes in the audience? Are you an athlete?

Fergal - Very much an amateur athlete.

Chris - What's your event?

Fergal - Well, I row and I run.

Chris - What's your name?

Fergal - I'm Fergal.

Chris - Any questions for someone who's a professional in this? How you can make your amateur turn professional?

Fergal - Well I'd love to know, is there a correlation between fitness and VO2 max and fitness and heart rate because I know myself. I have a really low maximum heart rate, but my resting heart rate is quite low. But my maximum heart rate is about 170. I just wondered why that is.

Chris - Maybe you should start by telling people what VO2 max is.

Dan - Yeah and actually, it's interesting because that's actually where my research is.  VO2 max is what it says. It's the maximum volume (V for volume) the maximum volume of oxygen that you can take up from the air and use for the generation of energy. So, how much oxygen, there's a point where, it doesn't matter how much you take in, you can't use it. This is the primary way we assess people's cardio, respiratory fitness and to put into context, how do we do it? Pretend to put somebody on treadmill. We make them run and we make the gradient go steeper and steeper, and steeper, until they can't run. We measure the expired air and we can calculate O2 and CO2. Really, in relation in terms of VO2 max to describe fitness, it describes for cardiorespiratory fitness and cardiovascular fitness. So, we know that the best endurance athletes typically have higher VO2 max scores. The other question was about heart rate. Heart rate is a really interesting one because the perception is, that if you get cardiovascularly fitter, then you'll start to see a decrease in your resting heart rate. That's correct and we know that Tour de France cyclist can tend to have resting heart rates of about 28 beats per minute.

Chris - Normal of course, being about 70, isn't it?

Dan - Normal being around 70 beats per minute, so, it's incredibly low. But there's a paradoxical response because the general conception is that if you're exercising and you want the heart to pump that blood to the exercising limb, you'd expect the maximal heart rate to increase, it doesn't. The maximal heart rate starts to decrease and the reason for that is, if you think about the experiments going on in the corner, so the poor chap is still going.

Chris - Hang on. Younas, how are you getting on?

Younas - I'm exhausted!

Chris - This poor guy has been turning this crank Dave has given him, continuously throughout this evening's event. You've burned off 0.0049, so, nearly, 0.005 of a Mars bar. Well done!

Dave - I guess to be fair to him that he has actually burnt off probably three times that amount of energy because his muscles aren't very efficient, so he's probably burnt of 1 1/2 % of a Mars bar in 10 minutes.

Chris - Would you like to stop?

Younas - Yes.

Chris - Give him a round of applause. Well done.

Dan - So, the bit we were discussing and just mentioning was the fact ironically, that the maximum heart rate decreases. The way to think about it is that the heart itself is a muscle. What happens is, as you start to train, rather than having it beating faster and faster, and a great example is Younas doing that exercise, his muscles are getting tired. You don't want your heart getting tired. You imagine going out for a run and going, "My heart is tired. I can't exercise!" so, what happens is that the heart muscle, just like someone that goes to the gym, gets bigger, gets thicker, the cavity in the heart, the ventricle gets wider. So actually, what happens is, per beat of the heart, you can eject more blood per beat of the heart, which means you can now get more oxygen to the muscle. So, the adaptation is, the fact you're saying you've got a lower maximal heart rate is actually, I'd take that as quite a good sign. That's quite a good indication that endurance training is working.

Chris - What's your name?

Carlo - I'm Carlo from Cambridge. When you run uphill on a mountain, you tend to go out of breath quite easily. When you come down instead, your muscles still hurt, but your breath is okay. So, what's the difference between the work you do when you go uphill and the work you do when you do downhill?

Dan - That is a great question. Okay, so if you're going up a hill, and of course, that's a perfect question for in Cambridge, isn't it? But if you imagine running up a hill, what's happening is, and it's the exact same as we had in the experiment is that as that hill is steep, the amount of oxygen you're taking in, it's struggling to meet the demand. So, what happens is, in the muscles, you start to use an alternate energy source. You start to borrow energy and you're borrowing it from a source which is called anaerobic energy. The by-product of which is this chemical called lactic acid. This is what you start to feel and this is coupled with carbon dioxide and this is why you start to become breathless. When you go downhill, although you're perhaps running quicker, because you're running downhill, the way in which your muscles are moving is very different. Because what you're trying to do is, now you're trying to apply a brake. So, when you're going up the hill, the majority of the work is actually happening because the muscle is shortening. When you're coming down the hill, the muscle is acting as a brake. In other words, it's actually lengthening. This is the really cool biological adaptation. If a muscle is lengthening, it uses almost no energy. Think of a spring. So, if you've got a spring and it's sitting on the desk and you put your hand on it, you push the spring down, you're putting energy into it. It's like the muscle shortening. If it lengthens, all you've got to do is take your hand away and it springs back. There's no energy being imparted into the spring and that's the way the muscle works. So actually, although you're running at a similar speed, you're using less metabolic energy and actually, you start to recover.

Chris - You're listening to the Naked Scientists with Chris Smith and Dave Ansell, and Ginny Smith, and our panel of esteemed guests. We're answering the questions of the audience here. Give yourselves a round of applause. Ginny, what have you got coming in on the electronic routes of communication.

Ginny - So, I've got a message here from Vanessa on Twitter who asks, "Can increasing physical fitness directly improve cognitive ability, assuming other variables are constant?" And that's something I've heard as well. If you keep fit, it doesn't just do your body good. It does your brain good as well.

Dan - Yes, it's the adage is that we're all taught as kids, a healthy a healthy mind.  I'm not entirely sure whether I see it in my students. But there is certainly good evidence for this, that we know one of the things we get. We get a release of what are called endorphins in the brain and actually, this starts to bring about positive sensations. There are adverse effects as well. So we know that if we look at games like soccer - I'm going to call it soccer. I know it offends people - and you look at when most mistakes are made in the game. Most mistakes are made, anybody want to take a guess?

Male -   When England play?

Dan - Yes, absolutely. But they're made in the last 10 minutes of a game. What we know is, that there's a relationship between the number of mistakes being made and how tired somebody is getting. In other words, there's a link between a physical fatigue and cognitive ability. If you want to win a marathon race and everybody is together, the best time to actually make the attack and really go for it is in the latter stages because mentally, people are less competent because of physical fatigue.

Ginny - Actually, I've got a question that I wanted to ask. So, I've been reading a lot about this high intensity interval training recently. The idea that you can do just 30 seconds of really intense exercise and get the same benefits as going to the gym for half an hour. Is there any evidence behind that?

Dan - There's no doubt. I mean, you could sit here as a scientist and go of course, there's loads of evidence. The issue is, who does the evidence fit? So, the idea is that in this day and age, we haven't got enough time to exercise. So, it's more beneficial if you do 3 high intensity burst of 30 seconds exercise than going to do half an hour. There's plenty of data that shows this. The issue that I have as a scientist with this is, the studies have only ever been performed on physically active, highly trained individuals who can tolerate it. It's incredibly hard to ask somebody to work maximally for 30 seconds, have a couple of minutes rest and then do it again, and do that 4 times, and do that 3 times a week. When you apply it to the population that it was meant to fit, which is our sedentary population who were maybe the more obese population, they can't tolerate it. We have a mismatch between what the scientists are suggesting and it's perhaps you could argue slightly spurious in terms of the way they've communicated the information and actually, the way in which it can be applied to the more general population.

Chris - Anyone got any other questions for Dan? One over the back...

Julian - My name is Julian. I'm from Cambridge. I've actually got two questions. Firstly, we hear about fast twitch and slow twitch muscles. I assume that the fast ones twitch quickly and the slow ones slowly. But what's the actual difference between those two muscles? And then secondly, how quick is our 100 metres record going to go. What do you think the fastest we can ever do will be?

Dan -  Wow! Okay, we'll start with the easy one. So, fast twitch, slow twitch, yeah. We've got two broad categories of muscle fibre. If you look under the microscope at them, they do look distinctly different. A slow twitch fibre under the microscope actually has a very red colour to it.  And a fast twitch fibre has very white colour. Those of you that like to eat meat, if you look at chicken, it's white. Think about what a chicken does. It flaps its wings really fast. If you think about a cow, cows don't move very fast. It's red meat. Why? The red muscle is oxygenated muscle. It has to have  a blood supply to it and it's very rich in oxygen, it has lots of capillaries which allows the oxygenated blood to get to them. A fast twitch fibre, which is kind of Usain Bolt fibre, those fibres, they don't need the blood supply. Why? Because the energy is stored directly in the muscle. There's not a lot of it, but the energy in the muscle then can be used instantly for what's referred to as a much more explosive work that you couldn't use a slow twitch fibre for. The second question is, how quick can we ever get in the 100 metres. This is kind of how long is the piece of string question, isn't it? This is kind of dodgy water. Projections are, that within the next 10 years, you could see a 100 metres run at 9.3.

Chris - Usain Bolt told Richard Bacon on the BBC Radio 5 Live Bacon Show when asked, "What did you eat before your 100-metre dash?" He said, "Cheeseburger and chips." Would you recommend that diet? Is that a good Olympic record-breaking diet? Is that what you used to have?

Dan - Well, it's odd isn't it? It's going to be slightly - again, slightly dodgy water to get into. For a 100-metre race, if I'm brutally honest, before a 100-metre race, it makes no odds what you eat. It makes no difference at all. If you were dealing with an endurance athlete then I would say, the worst thing you could've done is eaten that.  His race is over in 10 seconds. He's using energy that is stored in the muscle.

Chris - What's your name?

Paul - Hi. I'm Paul from Cambridge. So, we're learning this evening that increasing your heart rate is very good, healthy, improves your stamina, general fitness and health. If I'm watching a horror movie, I tend to find my heart rate increases. What's the scientific benefit of say, The Exorcist compared to Nightmare on Elm Street?

Chris - Better still, can we substitute one for the other?

Dan - Yeah, I mean, there is a difference. There is a difference between what is in essence a more stress orientated response and what is much more a physical orientated response. Although we are raising the heart rate under those stress conditions, there are actually more adverse conditions because what you're doing is you're raising the heart rate but you're also raising blood pressure. That's why you get that classic stress response. What you want under exercise conditions is you want the heart rate raised but actually, you want to be burning energy. So, you want the muscles to be lengthening and shortening. So, the answer isn't, I'm afraid, to sit and watch very bad horror films.

Chris - It's a shame isn't it? I know we let Younas off a bit early because he was looking like he was about to die. But you better explain what actually did you find out of this experiment, Dave and Ginny?

Dave - I guess this sort of brings out the point, I really don't think that Younas would've wanted to burn off a whole Mars bar like that. So, why does exercise actually cause people to lose weight if actually, the actual energy compared to food you eat is tiny?

Dan - Yeah, I mean, it is one of the great questions really. We have to recognise, when we're talking about healthy lifestyle, it's not just about the exercise. It is a combination of exercise plus diet, plus actually, just generally looking after yourself. The key with exercise and this comes back to the question Ginny asked as well. Is actually doing it at the right intensity. We have to understand that what we're trying to target when we exercise is we're trying to burn, breakdown fat. So, you've got to exercise long enough that you start to metabolise and break this fat down. He did 10 minutes worth of work, we have to actually make sure the intensity is right and we actually have to make sure the duration is right in order to metabolise enough that we start to get the benefits. It starts to become cumulative. So a one off session, you're not going to get suddenly become very fit. But the adaptations, which is what we're after, this loss of fats and all these lovely physical gains we're talking about, it's a cumulative response. As you start to exercise, you will suddenly realise, "Actually, rather than go for 10 minutes, I can go for 12 minutes." There's been very small cellular adaptations in the cell right inside those cells, there's what's called a mitochondria and the mitochondria is where respiration in the cell takes place. We know that the mitochondria start to increase in their number in size as you start to train. That means you become more efficient at using the oxygen that we started talking about earlier on, so you can go a little bit further, and a little bit further. So, it's these very small adaptations that produce in the end, these bigger gains.

Ginny - So Younas, you'll have to come back again next week and do it again, it sounds like. He doesn't look too happy about that.

24:05 - Why Five a Day?

What's the evidence for 5 portions of fruit and vegetables per day? And do 5 apples add up to the same health benefit as mixed greens?

Why Five a Day?
with Nita Forouhi, MRC Epidemiology Unit, Cambridge

What's the evidence for 5 portions of fruit and vegetables per day? And do 5 apples add up to the same health benefit as mixed greens...?

Chris - Nita, keen on exercise?

Nita -   Sure, but keen on the other side of the energy balance equation

fruits

too, which is the diet,

which I think Dan just started talking about there.

Chris -   So, you're an epidemiologist.

Nita -   Yes.

Chris -   What is one of those when it's at home?

Nita -   In simplest terms, everyone knows what a doctor does.  You have a medical problem, you go along to a doctor, your GP.  An epidemiologist is somebody who deals with similar things, but on a population level, rather than on a one-to-one.  So, I would be interested in, why is it that hundreds of thousands of people get diabetes, or get heart disease, rather than focusing on the patient in

front of me.

Chris -   What are you finding when you do these studies?

Nita -   It's really important to have this population perspective because the end of one as we would say which is anecdotal, which is things like, we have enough evidence that smoking is bad for us, but individuals may say, "But my grandfather smoke 80 cigarettes a day and he lived until he was 100, so what's wrong with that?"  so, the population perspective is really important for us to form credible research. And what we have been doing, the group the I lead, is specifically interested in understanding how diet and nutrition, and foods can influence the risk of developing diabetes. 

Now, for decades, the focus has been on, once you have diabetes, how can you control that well. 

It's common sort of folklore what diet should people eat to have better diabetes control. But, increasingly, what we now know is that to prevent the disease in the first place there are lots of things we could do.  So, with these big studies that we have setup - and when I say big, we mean studies that - for example - one that I will name, EPIC Norfolk - is 25,000 people around this area.  We have another study which is about half a million people.  So, we're talking big studies.  We asked people, people who don't yet have diabetes, what foods they're eating, what their regular habitual diets are like, and then we follow them up to see who develops diabetes and who doesn't. And we look at other disease end-points too.  From that, we can work out, what are the big things that can influence the risk of diabetes?

Chris -   So, you can find out what a balanced diet is and a balanced diet isn't perhaps an ice

cream in both hands?

Nita -   So, you'll say, "okay, so you've got all these big studies.  What are your key findings?"  well, some of our very recent research has shown that for instance, eating high amounts of red and processed meat and also, drinking habitually one or more portions or cans if you like of these fizzy drinks or soft drinks can significantly increase your risk of diabetes over time.  We've also found things which can reduce risk of diabetes because we don't want to be only giving the messages of, "Well, if you eat this, this will up your risk of diabetes or of other diseases."  We also want to generate positive messages of what can you eat more of to reduce that risk.  I think, probably, no major prize's for guessing, we've found that fruit and vegetable intake is really important, but a particular nuance to that, recently that we wrote up a nice article about was that eating lots of variety of different fruits and vegetables is really important.  So, I think most of you know about the 5-a-day message which

is to eat 5 portions of fruits and vegetables a day for good health.  But we've recently worked out that, actually, if you are partial to say, apples, and you just eat 5 apples a day, that's actually not as good as going across a range of things, trying new types of fruits and vegetables, experimenting a bit.

Chris -   What do you think that 5 apples are not as good 1 apple, 1 tomato, a banana, and a cucumber and perhaps some lettuce then?

Nita -   Sure, really good question.  It's to do with the different types of content that you would get within the different fruits and vegetables.  Fruits and vegetables are full of thousands of what we call phytochemicals and they contain different proportions of vitamins, anti-oxidants, minerals, fibre content, the natural sugar content.  So, fruits and vegetables really vary in the amount of all these different hundreds and thousands of components.  So, by having a greater variety, you're taking the

best of different types basically.

Ginny -   I've got a question that's come in on Twitter from Wayne Jemell, and he asks, "Which diet is better, a high protein - so I assume he means low carb diet - or a high carb, low protein diet?"

 Nita -   So, there's a lot out there about people favouring particular diets and there's a whole host of diets that are becoming very popular - high protein, low fat, and so on.  The distilled information from the research is, it has to be a balance of food components within the diet.  The foods have more to them than only protein and carbohydrates that present what we call macronutrients.  But there's a whole host of other things that we eat in foods that matter.  So, a healthy balanced diet - one, that will help you to maintain a healthy weight is the important things.  Different things work for different people.  Sustaining a particular diet is the hardest thing to do.  So, if you identify a diet that

worked for you, that is the thing to hold on to.  There's quite a lot of research that it's the endpoint of maintaining good weight or losing weight if you're obese that matters.  Almost, whichever way you get to it, is not the critical thing.

Ginny -   Dan, I wonder if you want to come on in on that.  people are thin, they're trying to bulk up and perhaps put a muscle, think that they need lots and lots of protein.  Is that the case?

Dan -   Simple answer is no.  There's a couple of things on this that fascinate me with this.  There's a lovely saying that came from an American physiologist which is "fat burns in a carbohydrate flame".  So, to metabolise fat, you actually have to have carbohydrates.  So the idea of having a really low carbohydrate diet actually may well preclude you from burning fat and losing weight.  The second thing is, if we're talking about a balanced approach to life, we're talking about putting exercise in,

then the currency that you need is carbohydrates.  So, if you're asking somebody to say, "Well, I actually want this balanced approach.  Go and exercise."  But actually, the approach is a low carb diet and then go and exercise.  You've all I'm sure experienced it where you get this idea of a sugar low.  It's the same equivalent.  It's like trying to make your car go on empty.  And then we come to the question of, bulking up on protein.  There's a lot of pros and cons to this, but the simple answer really is, that if you just ingest protein, you don't actually get it into the place you need it.  Again, carbohydrate is the currency that's needed to enable the protein to be actually taken into the cell.  So, if we go for a really low carb, high protein diet, the protein is not actually serving the role that you want for.

Chris -   So, watch what you eat on that restaurant menu.  What's your name?

Mark -   I'm Mark from Cambridge surprisingly, same as everybody else.  I was just wondering. 

You mentioned, lots of people have the processed food and processed meats in particular are quite a high risk factor.  I just wondered whether it's the food itself that's the main risk factor or something that gets done within the processing that's causing that to sort of keep coming up?

Nita -   The whole story is not known.  It's likely to be the things that are done to the processed meat itself such as preservatives added.  There are nitrites that are added and also, it could be the very high salt content of some of these preserved meats because salt is a great preservative.  So, it's a combination of both of those things that you mentioned.  In terms of the processed meat, the quality of it itself.  As I was saying earlier, there is the issue of saturated fat within it as well.  So,

I think it's the saturated fat, plus, the things that you do to the meat to preserve it, together, that have the detrimental effect.

Victoria -   Hi.  I'm Victoria from Cambridge. It's a question relating to your suggestion that increasing your fruit and vegetables content will help prevent diabetes.  I'm just wondering why eating more fruits specifically will help prevent diabetes when you're trying to maintain a diet that's got a constant sugar level when fruit contains so much sucrose. I know it doesn't contain glucose, but in terms of how the body metabolises sucrose, why is that so much better for us than glucose from carbohydrates?

 Nita -   The main sugar in fruits is in fact fructose and fruits have a whole host of things within them, fructose being only one component.  So, what happens with eating fruit is that you get

the combination of these benefits together, things like the fibre, the antioxidants, the phytochemicals, the carotenoids.  There's literally over a thousand components and beneficial chemical compounds within fruits.  That's why they're beneficial.  Now, in regard to your question about, or the worry about, the sugar content?  Taken together, the benefits of all these other factors outweigh any potential harm of the relatively small amounts of natural sugar that you will get from a portion of fruit.  However, if you were to have a glass of juice of the same fruit, you would actually then have a whole larger number of fruit to make that one glass of juice.  So there, proportionately, you would get a larger load of sugar

coming into your body within acute response physiologically within the body.  But, eating fruits is actually a really great and healthy way to protect against diabetes, obesity and a whole host of other things because of those other components that go along with the sugar.

Chris -   What's your question?

Julian -   It's Julian.  I want to ask a question about diabetes.  There's a huge ticking time bomb we're told of about type 2 or late onset diabetes, but there were reports in the press to say that you can reverse type 2 diabetes by putting people on a very low - I think it was about 800-calorie a day diet for 6 to 8 weeks.  Do you have any further information on that?

Nita -   Yes, sure.  So, that is very promising and there are small scale studies of

those research group that have come up with that idea where they have shown that indeed, that is the case if you put people on very drastically low calorie diets.  In fact, they were even lower than 800 calories, down to 600, even 500 calories, can lead to what we call a remission of diabetes if people have it.  And there are claims that it may even cause reversal of diabetes.  There are some big studies by those groups now planned, so that those experiments if you like can be done on larger numbers.  And also, to see the feasibility of whether people can sustain those diets for those 6, 8, 10-week

periods of times, and how much input will be needed from, say, NHS staff to maintain people on those diets versus how much can be done independently.  So, a whole host of things to be worked out about feasibility and scope, but really promising.  And if that is the case, then even if it was remission rather than reversal, it is important to follow through on that.

Chris -   One person said to me that these low-calorie diets, these extreme low-calorie diets, regardless of whether or not they add years onto your life, they sure is hell make it

feel like you're living forever because it's so boring.  It's so hard to do.

Nita -   It makes you work hard.

Chris -   Ladies and gentlemen, Nita Forouhi.  Please show your appreciation.

Chris -   You're listening on the Naked Scientists with me, Chris Smith, Dave Ansell, Ginny Smith, and our esteemed panel of guests this evening, Dan Gordon, Nita Forouhi, and David Ogilvie.  We're talking about lifestyle and lifestyle choices, and how the world we live in can affect your health.  Nita, we've actually got a little experiment for you to take part in.

Nita -   Sounds fun.

Ginny -   So, we've been hearing a lot about how good for you, fruits and vegetables are and of course, one of the reasons they're good for you is because they contain vitamin C, but we were wondering whether, how you cooked your vegetables affected how much vitamin C was in them.  So, we've come up with a little experiment to find out.

Dave -   So, the first thing we've done is we've got three sets of carrots.  We took a set of

carrots.  We put it into a blender.

Ginny -   So, we cut up some raw carrot, we mixed it with a bit of water and we popped it into a blender, and then we have to filter out all the sort of big blocky bits of carrot that hadn't blended up properly.  So, we put it through a coffee filter, just a normal one, and we came out with some rather delicious looking carrot juice.  Then we did the same thing for the same amount carrot that we had boiled - and we boiled it quite efficiently.

Dave -   To the point that where we actually boiled all the water away because we weren't paying attention.

Ginny -   So, this is kind of school dinners, carrot boiled until it barely resembles carrot. 

We also did some in the microwave.  So, we thought we would see how much vitamin C is contained in each of these types of carrot juice.  Nita, could you come and give us a hand for a second?

Nita -   Yes.  So, what am I doing?

Dave -   Now, we've got some carrot juice.  We're going to use a reaction between starch and iodine for this and...

Nita -   Takes me back GCSE Science.

Dave -   Very much so.  So first of all, we're going to add about 10 ml

of...

Nita -   So, this is the raw, not boiled, not microwave carrot here.

Ginny -   Yes.  So, we're going to add some of these carrot juice to a cup that's already got a starch solution in it.  So, we just dissolved some corn flower in water.

Nita -   We're just pipetting this in?

Ginny -   Okay, so we've got some starch solution and some carrot juice in that cup and we also made up the same solutions with our boiled carrot juice and our microwave carrot juice.  Three orange

cups of carrot juice.  They don't look too appealing.  They're sort of slightly watery orange colour like maybe a very fake-looking orange squash.  Now Dave, what are we going to do to see how much vitamin C is in here?

Dave -   What we've got here is iodine solution and iodine can exist in two types - there's iodide and iodine and it's only the iodine which will react with starch and that gives you a really dark colour.

Ginny -   You might remember that from school, the sort of blue black colour you get if you drip some iodine on a potato or things like that.  Most people have seen that.  So, that's what we're looking for and, if we see that colour, that means that it's reacted and what does that tell us?

Dave -   The vitamin C will react with the iodine and keep it in the iodide state so it doesn't

react.  So, the more vitamin C there is there, more iodine we can add before it will react.

Ginny -   Okay, so we're looking for different shades of blue.  The darker the blue, the less vitamin C is in our juice.  The lighter blue will mean there's more vitamin C in there.  So, you can put the same amount of iodine in each of our cups and see how much there is.

Dave -   About 15 drops.

Nita -   So, this is a fair test I hope which is 15 drops at each, and I'll be going to count this down?  1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 - okay, that was 15.

Ginny -   Okay, so I can see there's a really bright blue colour at the top here

and we're going to swirl it a bit and see what happens.  Okay, so it's staying quite dark isn't it?  Which one was that?

Nita and Dave -   That's the raw one.

Ginny -   Okay, well actually hang on.  It's starting to get a bit paler now.

Nita -   1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15.  There we go.

Ginny -   Okay, let's give that one a swirl.  Again, we've got a bright dark blue to start with and we're swirling it and same in the other one.

Nita -   So, that's the boiled one.  And now, the microwave one,

there we go.

Dave -  The best...

(laughter)

Ginny -   So, when we did this in my kitchen earlier, we got a slightly different result.  It's exactly opposite to what happened earlier.  Now, that's interesting.  So, when we did this

earlier, we found that the raw one was a much lighter colour.  It seem to have more vitamin C in it; then the microwaved one was in the middle, and the boiled one was the darkest.  We appear to have the opposite.

Dave -   I think we've actually discovered something new by doing this experiment which is, if you leave raw carrot juice sit and lying around for a long time, the vitamin C will actually get destroyed, probably by enzymes and things floating around inside the carrot juice.  But if you cook it, it will preserve it and it will last a lot longer.  But if you do it fresh, you will find there's a lot more vitamin C in raw carrot than cooked carrot and a microwave carrot is somewhere in between.

Ginny -   We did notice when we took the raw juice out, if you hold up one of the other ones, you can see that the cooked ones are beautiful bright vibrant orange whereas the raw ones gone kind of darker and duller, and it started off as similar colour to that ones. 

So, that shows us that in a couple of hours between making this in my kitchen earlier and bringing it to the show, something has happened to that raw one that's obviously got rid of some of the vitamin C.  Is that what you would expect to happen?

Nita -   Actually, no I wouldn't.  I would expect the goodness to be there.  The vitamin C should be there and it should be beneficial for you.

Ginny -   Fair enough.  There we go.  That's science.

(clap)

Chris -   Anymore questions for Nita

?

Mark -   Hi.  I'm Mark from Cambridge.  I was just wondering, to what extent do the positive and the negative risk factors cancel out?  I really like sausages, so is there an amount of fruit that I can eat to compensate for me eating the sausage or will the negative factor of the sauces never be compensated?

Nita -   Nice try.  It's all about the balance and it's not about, if I

have a little bit of this, is that still bad for me and can the harm never be compensated for by the good things?  No, it's not like that.  It's about portion control.  It's about the balance of things.  If you are partial to some things, if you have it in moderation, or small amounts on the odd occasion, rather than a daily thing, then I think it kind of balances out.  Much of our research when we've analysed the data on these large populations does show that.  So, we are not kind of "party poopers" doing this research saying, "You mustn't eat this ever in your life."  The point is, certain things, if eaten regularly habitually, day in and day out in large quantities have the detrimental effect.  Having small amounts of something is okay, but yes, do eat the beneficial things on a habitual regular-and-often basis.

Chris -   Nita, thank you very much.

43:40 - Changing behaviour for health

We all know that exercise and a healthy diet is good for us, but is there anything that government can to help us follow the advice?

Changing behaviour for health
with David Ogilvie, MRC epidemiology unit, Cambridge

Chris - You're listening to the Naked Scientists with Chris Smith, Dave Ansell, and Stairs at milan stationGinny Smith at the Cambridge Science Centre and our panel this evening who are Dan Gordon, Nita Forouhi, and David Ogilvie. David also works in the same department as Nita. You're also a sort of an epidemiologist, but you do something a bit more, I suppose, applied.

David - Yes, we look at physical activity rather than diet and we look at a problem that's a bit upstream if you like. There's lots of evidence that physical activity is good for health and most of us would benefit from doing more of it. How can we help the population become more active? I think we all know the message about physical activity and we've been telling people this for quite a long time. We're not seeing a dramatic increase in the number of people who are very physically active. And so, we're interested in whether there are other things we can do particularly about the world that we live in, the environment that might help support a more active lifestyle.

Chris - I put in some numbers on this because the National Obesity Forum put out their State of the Nation's Waistlines Report last week and I was quite staggered to learn that about 1 child in between 4 and 5, first of going to school is already overweight. So, what proportion of those kids are actually walking to school I wonder? Do you think that's partly to blame?

David - Well clearly, obesity is released in both diet and activity, but there has been a decrease over the last 10 or 20 years in the number of children walk into school. Of course, that mirrors changes more broadly in society. As adults, we tend to drive more than we used to for all sorts of other reasons. So, walking to school or indeed, cycling to school is something that, some studies have shown that children are more keen to do more than their parents sometimes realised. We're very interested in the possibility of encouraging people to establish healthier lifestyles, as early in life as possible, in the hope that they'll grow up into adults who want to continue to be active throughout life

Chris - But how do you think we need to go about that because taking my own workplace at the hospital, you have to struggle to find the stairs. I'm largely chained to a desk all day in my job. I mean, even the doors open automatically. So, that must be contributing.

David - Well of course, if we went back 50 or 100 years, most of us will be doing much more physically strenuous work than people of these days. Of course, there are reasons for having lifts in hospitals and not making everyone climb up and down the stairs.

Chris - I'm not proposing we make the patients walk. It's actually quite funny. The lifts in Addenbrookes actually talk to you and they say level 1 and level 2, and we think they've missed the trick actually because we think they should put something in the voice over which if you're getting at the ground floor and press level 1, it says, "Get out and walk you lazy!" what do you think? Do you think that works?

David - There are some studies going on not ours but elsewhere in the world looking at ways of altering how lifts work to encourage people to walk. For example, they're making lifts only stop in every 2nd or 3rd floor. But you're right, for some of us, there may be a limit to how much activity we can do while we're at work, but one of the things that may be more open to change is how we travel to work.

Chris - The thing is that having cars has made it so easy for people to live where they like and work where they like. If we wind the clock back to your notional 50 or 100 years when people weren't endowed with cars, people tended to live near where they work, so they tended to walk or to ride on a bike, didn't they?

David - Absolutely. We are dealing with the effects of technological advance, the automobile which has obviously transformed society in many ways over the last century. The thing is, even though most of us these days have cars, it doesn't mean we have to use them all the time. A place like Cambridge of course, many people do live close enough to work, to walk there or to ride a bike. But just because you live further out in the country for example, it doesn't mean you couldn't include some walking and cycling

Chris - I think there's a relationship then - people who live further from the town centre, are they more obese than people in the town centre?

David - Well, it's not that simple because there's lots of other confounding factors about how different types of people live in different places. Of course, as adults get older and have children, they often tend to move out towards the country because they're looking for more space and bigger house or whatever. So, one of the things we're interested in is studying commuters and how people travel to work and how that changes over time, and how that's related to the environment, and the transport system.

Chris - What about also the way we construct housing because if you live on a street where you've got a car parked straight outside, but it's a dangerous road, you wouldn't want your children walking on there? Those sort of factors must also make a difference.

David - Yes, so there's lots of studies showing that people who live in some types of neighbourhoods are more likely to walk for example or be physically active in general than others. There's lots of factors that might be in there. Sometimes it's about perceptions of safety. Is it safe to walk and cycle in the area? Would you let your children out unaccompanied? But it might also be about, what destinations you have that you can walk and cycle to? If you live in a village with no amenities and maybe no bus either then you are kind of limited to using the car to get to places that might be several miles away.

Something we're interested in is, everyday activity for ordinary people, when I hear Dan talking about Olympic cycling and high intensity training and so on, it does make me feel quite tired because most of us obviously aren't going to be Olympic cyclists. Most people in the country would benefit from becoming more active, but it doesn't have to be anything exceptional like that. it can be in every day travel, the kind of activities that anyone could do.

Chris - What's your name? Where are you from?

Chris - Chris from Cambridge. I've never learned to drive. I've always had to walk everywhere because I won't cycle in Cambridge either. It's a death trap. I go on walking on holidays and I frequently notice people much younger than me really struggling because they drive everywhere. I usually ask them, I say, "Do you drive everywhere?" and they usually say, "Yes." But the thing that worried me lately was that I read that simply sitting is supposed to be terribly bad for you and they're now encouraging people to stand up at work. Although I can walk for miles without getting tired, if I stand, I get very tired. So, what is the latest on this?

David - So, the evidence on sitting time or sedentary behaviour is developing - we know more about the benefits of physical activity than the harms of spending a lot of time sitting, but there's a lot of research going on into that at the moment. But you're right to pick up on the issue of driving and walking or cycling. Of course, if someone was to make a change in their life, even if they drive to work every day, if they left the car at home twice a week and walked or cycled instead, they're not only becoming more active. They're also reducing some of their sitting time. Over time, they might develop a confidence to do more of that.

Jess - My name is Jess from Saint Yves. In the year past, we had Andy Murray, we had Wiggo winning his race. We did have England playing well at cricket. Does that mess up your statistics when you see a spike of people buying bikes and trying to get fit, emulating their heroes?

David - We're still analysing data from 2012 and 2013. So, I can't answer the question directly, but what I would say is that we're not so focused on measuring whether people have bikes for example. We're interested in looking whether people change their behaviour and sustain that change. We follow people up over years. The aim here is not to have a flash in the pan, a New Year's resolution which is expired by the end of January. We're looking at ways of enabling people to build more sustained change so that their health will benefit over the longer term.

Ginny - I've got a question here on Facebook from Nish Nayar, who I think this is really directed to all of you. She wants to know what's the best approach for weight loss for a person who's genetically prone to be overweight.

Nita - I'll kick off with that one. We have a reasonably good research from our unit and elsewhere which shows the universal benefits of both being physically more active and of having a good diet. What we know about the genetics now, is particularly for physical activity, if you are genetically predisposed to being obese, the more physically active you are, the greater the benefit to be had. So, it's not a situation of, "Well, it's in my genes. There's not a lot I can do." The sort of research I was talking about before in terms of showing an interaction between some of these lifestyle things like diet and physical activity, and our genetic predisposition. So, my advice would be, it's not one or the other. Both in combination will work because both diet and physical activity are the two sides of the energy balance equation.

Dan - If I can chip in, I mean, the other thing is, I mentioned earlier on about the idea of this population we now know who are non-responders. But we only really understand that they're non-responders for doing cardiovascular exercise. And so, there are still benefits even in a population group who are genetically predisposed to this kind of not losing weight or doing different forms of exercise. So, we still know that even if it's resistance based exercise, even if it is more, what we might even call, I suppose, more callisthenic kind of exercise which is this low intensity work, will still have a benefit even if it's not tangible in terms of weight loss, we often forget. If there was a 4th member for the panel here, it's the psychologists because there's a huge benefit in terms of psychological well-being that comes from doing exercise and we forget. There's so much data now that ties in exercise with depression. So, there is this link. So, although we are perhaps thinking about the physical responses, we've also got to think about this more psychological responses that comes.

Chris - What's your question?

Keith - Keith Porter from Cambridge. We're told that the brain uses more energy as in the average muscle. Can you tell us how many times crosswords we'd have to solve to make the equivalent of a 5-mile walk?

Ginny - I think there has actually been a few studies looking at the energy consumption of the brain and it uses a ridiculous amount at rest. So our brain uses something like 20% of our daily calorific intake, but I'm pretty sure that it doesn't use that much more when you're thinking because actually, even when we're doing nothing, our brains are hugely active. There's this state of daydreaming where there's actually so many connections going on that I think you wouldn't find doing too many crosswords to burn off that many calories. But we do know that they're very good for protecting your brain and keeping it active and keeping you sharp.

Dan - Just to give you something to think about when you leave. There's some data that's come. We've had it from our lab and some labs in the states that have shown that if you think about doing exercise, you get fitter. And this is quite interesting, yeah. So, we ran a very simple study which was, we had students doing some strength exercise and they were just doing some very, very basic strength training. We had another group who thought about doing strength training. Now obviously, the guys who did strength training, they got the changes in muscle mass, but it was very, very interesting that the group who thought about doing strength training for a number of weeks actually showed - they didn't show increase in size of the muscle. But actually, when we tested what they did before, and what they did afterwards, they could lift more weight.That's something to think about as to, why.

Chris - There were some evidence that actually exercise does give you new nerve cells in your brain as well. Perry Bartlet who's a researcher at the University of Queensland in Australia actually showed that in people who are either on anti-depressants or taking regular exercise, you increase the numbers of new nerve cells being born in the part of the brain called the hippocampus. Instead of those cells being born and dying, they seem to survive for longer. So, either anti-depressants or exercise would potentially boost your memory, or doing something else as well although maybe that would be a memorable experience for another reason. Let's get experimental, Ginny.

Ginny - Right. So, we've been talking about all sorts of things that your body needs to keep going. Now, of course, there are all these other trace elements and things that we need. A lot of them, you can get in things like fortified breakfast cereals. So, we've got a box cornflakes here and Dave is just going to take the bag out. Now, I'm going to have a look on the back and see what's in these cornflakes. So, we've got vitamin D, vitamin B6, we've got folic acid, we've got vitamin B12, we've got riboflavin, all sorts of things. We've also got iron. So, we're going to have a look at how we can see, how much iron is in this bag of cornflakes and actually extract some of it. So, what do we need to do, Dave?

Dave - So, the first thing we're going to do is try and smash these up into very, very small pieces.

Ginny - Shall we get someone to help us with that?

Dave - Yeah.

Ginny - I think we've got a volunteer at the front here. What's your name?

Ellie - Ellie.

Ginny - Brilliant! Ellie, so we just need you to scrunch up these cornflakes.

Ginny -  Oh no! We might get a bowl to put them in. I think that might help.

Dave - It was cunning plan.

Ginny - It was. Okay, let's pop what's left of the cornflakes in the bowl. We're going to try putting them in the blender. Maybe we'll try putting them in the blender. I think that might be a bit more efficient.

(blending)

Ginny - Wonderful! Okay, so now, we have cornflake dust. Does anyone know how you can tell if something is made of iron?

Chris - Let's find out. Tell us something special about iron?

Fergal - It's magnetic?

Ginny - It is magnetic, exactly. So Dave has here, a special super strong magnet. How strong is it?

Dave - I think it probably would hold about 20 or 30 kilos on a piece of iron, so it's quite a scary magnet.

Ginny - We're not going to need 20 or 30 kilos, but we are going to get Ellie to come up and help us again. So, what are you going to ask her to do, apart from tread on the cornflakes?

Dave -  So, what I'd like you to do Ellie is push the magnet around the cornflake dust.

Ginny - Just above it, so you don't actually need to put it in, just hold it just above and hopefully, we should find that some little bits of iron are going to actually jump up onto the magnet. Turn it over. Let's have a look. There we go. So, can you see what's on the magnet?

Ellie - Tiny bits of dusty stuff.

Ginny - Yeah, we've got some tiny little bits of what looks like cornflake dust, but that jumped onto the magnet. You didn't actually touch the magnet to the dust did you?

Ellie -  No.

Ginny - So, it couldn't be that they just stuck to it. They must've actually jumped up. So, they are tiny little bits of iron. So, when you're eating your breakfast cereal, it's not some kind of compound chemical mixed in, you're actually eating tiny little bits of iron.

Dave - When I first did this, I assumed that they put rust in or some kind of rust, some kind of iron compound. But actually, if you put rust in there, it makes the cornflakes kind of go brown and horrible coloured. But if you actually put in solid lump, little tiny iron filings, it turns out that it both looks better and it's absorbed better in your gut.

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