Tegan Taylor: Norman, are you familiar with the game ‘Would You Rather’?
Norman Swan: No, but what would I rather do?
Tegan Taylor: Well, basically it’s would you rather have feet for hands, or hands for feet, that sort of thing.
Norman Swan: Oh right, so it’s what you play with the kids in the car on the way to the coast.
Tegan Taylor: Yes, but I’m gonna do like a nerdy version of it with you today. Would you rather never exercise again or never eat vegetables again?
Norman Swan: I think I’d rather never eat vegetables again than stopping exercise.
Tegan Taylor: I think so too. Well, kind of, sort of, a little bit, that is a little bit what What’s That Rash? is about today.
Norman Swan: Which is the podcast where we answer the health questions that everybody’s asking.
Tegan Taylor: Before we go on, would you rather have feet for hands, or hands for feet?
Norman Swan: I would prefer hands.
Tegan Taylor: Me too, like a monkey.
Norman Swan: How would you eat? Write? Do stuff? Pick your nose?
Tegan Taylor: Yeah, exactly, I would be able to climb trees so much better. Oh my gosh, I’d get so much better at climbing. Okay, let’s go, let’s go. Cathy has emailed in today saying, ‘My husband and I have been sticking to a Mediterranean diet (ding, ding) for over a year and recently had a holiday in Italy, i.e. a Mediterranean country. We had erroneously thought it would be easy to have a healthy diet in Italy, but now realise that this is not true.’
Norman Swan: Mortadella!
Tegan Taylor: Cathy says, ‘I would like to suggest that the reason people living by the Mediterranean Sea may have longer lives than most is the number of hills and stairs they have to climb in daily life, and has little to do with what they consume.’ And Cathy says, ‘Could it be that exercise is more important than diet?’ Rob has a similar question, basically asking specifically about blood glucose levels; diet or exercise? So today, Norman, we are doing the ultimate showdown; diet v exercise. And imagine that this Mediterranean diet bell is sort of like a wrestling match bell. [rings bell]
Norman Swan: Yeah, get it all out, get it out of your system before we start.
Tegan Taylor: It’s getting so many ding-dings today. All right, diet versus exercise, let’s go.
Norman Swan: So why don’t you give us a bit of history here, because we’ve never done this before, in terms of nutrition.
Tegan Taylor: Oh gosh, it’s so interesting, and it’s also so recent. Well, I think the thing is that for most of human existence we really didn’t have a lot of choice as to what we ate. It was like, what can I kill or forage? What grows in my area? What have my ancestors gathered in summer so that we can eat in winter? The word ‘diet’…
Norman Swan: We also didn’t have much choice about labour-saving devices or motorcars.
Tegan Taylor: Excellent point. Diet and exercise, the decisions were largely made for us. I was interested to discover that the Greek word…diaita? Greek scholars, please…
Norman Swan: Buggered if I know.
Tegan Taylor: …please feel free to email me and tell me how much I mispronounce. Anyway, the word basically means ‘way of living’, the way you exist in the world. It’s a very holistic view of diet as a lifestyle rather than just the food that you eat, which I thought was interesting. But the actual nutritional sciences era probably started in around the 1700s with a Scottish man…
Norman Swan: Of course.
Tegan Taylor: James Lind.
Norman Swan: Yep. So, people who know their history might know the story of James Lind. One of the conditions that bedevilled long distance sea travel was scurvy; bleeding, teeth falling out…
Tegan Taylor: Scurvy is cooked, it’s such a…it’s so gnarly. It’s like all your old wounds open up again.
Norman Swan: Indeed. And it was a high cause…it was a significant cause of death. And you have to remember this was an era where illness and disease killed more military personnel than warfare. And so if you could actually find something that preserved the health and wellbeing of your troops, you would actually have an advantage. And in fact…there’s a long story here but it’s for another day…one of the reasons the British were so successful at colonising was that they had some secret medical weapons which others did not have, not against themselves but to protect their health. But anyway, that’s another story. Nobody knew what caused scurvy, but James Lind wanted to do a randomised trial to find out.
Tegan Taylor: He did, and in the past we have criticised studies much larger than this, but he had 12 guys with scurvy, I suppose recruiting subjects was a thing as well, and they received different dietary interventions. And I don’t know how he chose what to intervene with, because one of the things was seawater, like making people drink seawater to see if it cured scurvy.
Norman Swan: Well, he concluded that being at sea your diet was restricted, and therefore you might be taking things that would bring on scurvy, or some people might be taking things that might prevent it, or there was a deprivation syndrome going on. So he tried various dietary interventions.
Tegan Taylor: Such as seawater, as I said, cider, vinegar, a mixture of garlic, mustard and horseradish, barley water, and (crucially) citrus fruit. And that was what he demonstrated, obviously, that citrus fruits could both prevent and cure scurvy, which laid the groundwork for later vitamin C being discovered.
Norman Swan: And again, one of the earliest examples of a randomised clinical trial.
Tegan Taylor: So the actual vitamins themselves, that was a discovery…well, at least it was named by a scientist called Casimir Funk, coolest name ever. Actually, if you think there’s a cooler name in science than Casimir Funk, email us, thatrash@abc.net.au, I challenge Casimir Funk to out-name anyone that you can give to us, but I’m happy to be proved wrong. Anyway, Casimir Funk was the guy who came up with the word ‘vitamin’ because he thought it was an amine, a nitrogen compound, and he thought it was vital, and so that’s where we get the word ‘vitamin’ from. Scientists later discovered that you didn’t need an amine group for something to be a vitamin, they dropped the E, but the name otherwise stuck.
Norman Swan: Okay, so we’re now arguing the case for diet being the most important thing. So let’s just do a bit of rah-rah for diet here. And one of the rah-rahs is the Framingham Heart Study, which started in 1948, following thousands of people in the town of Framingham in Massachusetts.
Tegan Taylor: I think those big diet pattern studies, not just focusing on a single nutrient like a vitamin but diet patterns, that’s a very mid 20th century onwards thing, pretty recent I think, really.
Norman Swan: So they showed, you know, high saturated fat, the Western diet was bad for you. Really interesting studies. Again, pushing the diet side of this story is that when they developed rationing in the UK, they used a leading nutritionist, I think she was at Cambridge University, designed what was considered then to be a healthy diet, and in fact it was quite a healthy diet, and rationing restricted unhealthy parts of the diet, and things like coronary heart disease did decline during the war, because rationing put you on a healthier diet. And then there was Ancel Keys.
Tegan Taylor: So Ancel Keys is one of those people whose name…you know how there’s this sense that everyone’s born already knowing all the lyrics to Beatles songs? I feel like I kind of knew who Ancel Keys was before I even knew who he was. And one of the things that he is famous for is what’s called the Seven Countries Study. So he basically looked at…
Norman Swan: He rang the bell for the Mediterranean diet.
Tegan Taylor: He sure did, he basically was the guy who was first like ‘Mediterranean diet!’…
Norman Swan: But it was mostly Crete that he studied. It was the Greek island diet that he particularly lionised. A lot of the idea about cholesterol really consolidated in Ancel Keys’ work, although it was there in the Framingham Study as well.
Tegan Taylor: And what these studies are looking at are basically mortality and death. So like, what do you eat and how do you die? And so to sort of come back around to this diet versus exercise thing, it turns out diet is pretty important. So I don’t know how many points that tallies up on the side of diet, but there’s a few there.
Norman Swan: And one of the themes that we’ll come to in a minute is it depends on what you want, what you’re trying to achieve, whether diet or exercise is going to work, not just our personal preferences. So let’s go to the exercise side of the equation. How does it measure up? Is it going to win the prize?
Tegan Taylor: Well, let’s have a look. So, I mean, in a similar way, I mentioned some pretty recent stuff with diet and nutrition. Obviously we’ve known that food is important for our health for centuries, decades, millennia…
Norman Swan: And speaking about the Greek island diet, you know, they ran a lot, these marathons, taking messages…
Tegan Taylor: One guy ran and then he died. I don’t know why people now suddenly want to do marathons, when the famous first marathon was pretty bad for that guy’s health.
Norman Swan: But that was because they killed the messenger. He had a message, and the person who received it didn’t like it that much.
Tegan Taylor: Anyway, let’s talk about exercise. We have known that exercise is good for you in moderation for a while. Susruta from India is one of the first known physicians to prescribe moderate daily exercise to his patients. This is 600 BCE, so a little while ago now. But the paper says it should be taken every day, but only to half extent of his capacity, otherwise it may prove fatal. I mean, that’s technically correct. I don’t know about the ‘half your capacity’ thing, but if you do exercise too hard, you could die.
Norman Swan: Well, if you’ve got already got heart disease, but it’s actually quite an unusual complication of exercise. You can go pretty hard.
Tegan Taylor: The other thing that Susruta said was, ‘Diseases fly from the presence of a person habituated to regular physical exercise.’ Norman Swan, fact check please.
Norman Swan: Absolutely, 100%, and I use the ancient Greeks as my other reference here.
Tegan Taylor: Okay, please explain.
Norman Swan: Well, they used to like running around with no clothes on and lionised exercise as a very important part of spiritual life.
Tegan Taylor: I mean, in terms of communicable diseases, I think if you were running around naked, people would give you a wide berth, and you’re probably less likely to catch something from them.
Norman Swan: Yeah, true.
Tegan Taylor: Actually, did you pepper the research document with just Scottish guys? Because there was another Glaswegian who is important in the exercise health story.
Norman Swan: Yeah, this is Professor Jerry Morris, who ended up in London, but yes, came from Glasgow, and he did this fascinating study comparing the risk of heart disease between drivers of double-decker buses and the conductors who would run up and down the stairs taking the fares.
Tegan Taylor: We have talked about this one before, I think.
Norman Swan: We have. And he found that the drivers had much higher rates of heart disease than the conductors who climbed the stairs. He also did it in the postal service; postmen who delivered the mail on bike or foot had fewer heart attacks than sedentary men who served behind postal counters or as telephonists or clerks. So, you know, if Jerry was in the studio, he would be pushing exercise really strongly.
Tegan Taylor: So that’s, I guess, a potted history of the origins of the science of diet and exercise. Lots of asterisks at the end of that, we cut out a lot of stuff. So now I really think if we’re going to compare the two, we probably need different arenas for this, because, as you said before, it depends what you want, whether diet or exercise is more important.
Norman Swan: Well, let’s start with weight loss. It’s very hard to do enough exercise that will compensate for swallowing calories in your diet. So if what you’re wanting is weight loss, you’ve actually got to change your dietary pattern and reduce the intake of cheap empty calories, for example, so that you are tailoring your energy intake to your energy output. Now, once you do that and you add exercise, you do get added benefit, but it’s very hard to lose weight if you’re relying on exercise, it’s just so inefficient in terms of burning calories. That’s not what you get from exercise. You get a lot more from exercise than weight loss. So diet wins, you know, one-nil on weight loss. Well, it’s not quite one-nil, it’s one versus 0.2.
Tegan Taylor: Very scientific, very specific. So, weight loss, really important for some people, less relevant for lots of us. What about other factors or facets of health? What about…?
Norman Swan: Let’s take cardiovascular fitness.
Tegan Taylor: Yes, you took the acronym right out of my mouth.
Norman Swan: So cardiovascular fitness, it’s exercise, strengthening your muscles…
Tegan Taylor: Well, cardiovascular health. Do you mean…when you say ‘cardiovascular fitness’, do you mean your heart…?
Norman Swan: Your cardiorespiratory fitness, effectively your ability to exercise without getting breathless, lift things, do things, have good muscle strength.
Tegan Taylor: How does that translate to cardiovascular risk of something like a stroke or a heart attack?
Norman Swan: So exercise has an almost immediate effect on reducing your risk of sudden cardiac death. People talk about sudden cardiac death being a problem of exercise. In fact, exercise reduces the risk of sudden cardiac death, and it does it very, very quickly.
Tegan Taylor: I’m surprised to hear that. I think I thought it was like you’re sort of playing the long game, you’re laying a lot of groundwork throughout your whole life so that you don’t get a heart attack when you’re in your 60s or something like that. How quickly are we talking?
Norman Swan: There is truth to that, but you get very immediate effects of exercise at a moderate level. Why do we do it every day or two? It’s because the effects, the immediate effects, tend to disappear after a day or two, and you’ve got to do it again for them to come back. So there are long-term effects in terms of muscle strength, of improved cardiac output, the resilience of the cardiovascular system. But what happens when you take exercise is that your blood vessels expand, your blood pressure goes down. It goes up initially, but then goes down. Your pulse rate eventually drops. There are all sorts of things. Your sympathetic nervous system gets settled down.
So after exercise, your body goes into this state which is actually a state of reduced cardiac risk. But you’ve got to repeat the exercise in order to gain that benefit. So repeated exercise is for both its immediate effects and its long-term effects. By the way, it’s similar for smoking; when you stop smoking, the effects happen within hours, days and weeks, not necessarily years, there are benefits over time. So diet does have an effect on cardiovascular risk, but it’s hard to change your diet quickly enough to have that effect. Where we’re coming to with all this is exactly as you say, it depends on what you want. So if you want cardiovascular protection, you’ve got to do both.
Tegan Taylor: Okay. So we need to touch base on our score, which is very scientific and not at all imaginary. We had one versus 0.2 when we were talking about weight loss before, one being diet and 0.2 being exercise. What are we up to when we add in cardiovascular health?
Norman Swan: I think that we’re on two-all really, with a bit of 0.2 there for exercise. So in the end it’s pretty equal.
Tegan Taylor: Well, the question that Rob asked was specifically about blood glucose control. What do we know about that?
Norman Swan: A lot of that is diet, but some of it is exercise too, because if you exercise, particularly muscle strengthening exercises, you increase the bulk and metabolism of a highly metabolically active tissue, which is muscle. And muscle metabolises sugar. And muscle is very important in terms of sensitivity of the body to insulin. So if you change your diet to one which is higher in complex carbohydrates, et cetera, you will help your blood sugar, but you will also help your blood sugar in the long term by exercise, by strengthening muscles and by having strong muscles, because strong muscles prevents your blood sugar spinning out of control.
Tegan Taylor: Okay, so, score check?
Norman Swan: We’re still…now we’re at three-all really, aren’t we, thereabouts?
Tegan Taylor: Sure, why not. So okay, so I asked you before if you’d rather never exercise again or never eat a vegetable again, and you said you could do without veggies but you couldn’t do without exercise. So you are team exercise, I’m guessing, behaviourally.
Norman Swan: I think I am, yes.
Tegan Taylor: Yeah, me too.
Norman Swan: It’s so hard to control my out-of-control appetite, that’s the problem.
Tegan Taylor: Well, it’s easier to find an hour to go and do something active than it is to coordinate all of the different food and food environments that you find yourself in day-to-day.
Norman Swan: Correct. And that’s one of the issues here, is that it is easier to change your exercise focused lifestyle than your dietary lifestyle, which is ingrained in habits, your appetite control is set when you’re in adolescence, and sometimes it’s really hard. And also if you don’t have as much money in your pocket to buy healthy food, or you’re living in a part of Australia where healthy food is harder to get or more expensive, then getting out and exercising is a really important thing to do.
Now, there are other things where exercise is really much better for you, and that is, for example, in the prevention of osteoporosis. You want weight bearing exercise, you want high impact gravity-based exercise that stimulates the growth of your bone. So that is much more important than your diet when it comes to osteoporosis, for example.
And then there’s brain health. And the evidence on brain health is that you can’t separate out diet from exercise, that these factors which both protect the brain and put the brain at risk work together, so you can’t separate the two.
Tegan Taylor: Well, that’s probably lucky, because it sounds like it’s roughly a tie and this was a false dichotomy anyway.
Norman Swan: I think it was.
Tegan Taylor: Completely imaginary face-off.
Norman Swan: But a good challenge, thank you very much.
Tegan Taylor: I think so too. And there have actually been studies looking at what we do with this information, about the fact that some people can only do one or the other, and people have looked at what is easier to do. And, no surprise, exercise is easier for people to implement than diet change, as you and I have already established in our n-equals-two study.
Norman Swan: It is.
Tegan Taylor: So, what do we say to Rob and Cathy?
Norman Swan: You were going to the wrong restaurants in Italy.
Tegan Taylor: Where would you recommend? Apart from the coffee gelato place.
Norman Swan: The whole thing about the Mediterranean diet is that the diet changes around the Mediterranean. And Ancel Keys’ work and others focused on the Greek islands, so that was the Greek island diet. And sure, you go to Italy and you eat processed meats, it’s not a very healthy diet. But the traditional Italian diet is pretty healthy and not too different from the Greek island diet. You’re getting your protein from legumes, you’re not eating that much red meat, and you’ve got complex carbohydrates. So there is a version of that, but when you’re there on holiday and stuffing your face with prosciutto and mortadella…
Tegan Taylor: Okay, so final word, Norman, a question without notice, if someone’s listening and going, okay, diet, exercise, both important, what do I do today? What’s one thing that I do today in each of those columns to improve my health? What do you recommend?
Norman Swan: Make the majority of each plate filled with vegetables and the minority of the plate filled with protein. And exercise, get out there and do some (any!) and then progressively increase it as time goes on.
Tegan Taylor: Add a serve of veg, add a serve of exercise, and add an email to thatrash@abc.net.au with your health question. Rob, Cathy, thank you both so much for your questions today.
Norman Swan: Now we want some special feedback from you.
Tegan Taylor: So this is usually where I would say what your feedback has been. Well, this is a note to say that we are now back. We’re back from holidays, we are reading and responding to your email, so please send in your questions for 2026. And, like I said a few weeks back, I want to know what has been said around the dinner table over the holidays, send us your slightly unhinged relatives’ theories about health, your questions that you want us to tackle…
Norman Swan: Uncle Arthur on vaccines, we’d love to hear it.
Tegan Taylor: And we will tuck into those questions in the coming months.
Norman Swan: See you next week.
Tegan Taylor: I’ll see you then.
