Science Interviews


Tue, 28th Jan 2014

Changing behaviour for health

David Ogilvie, MRC epidemiology unit, Cambridge

Listen Now    Download as mp3 from the show Exorcist, or Exercise: what's healthier?

Chris - You're listening to the Naked Scientists with Chris Smith, Dave Ansell, and (c) Dela Andy Kumahor

" alt="Stairs at milan station" />Ginny 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.


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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