Smart People Podcast

SPP: I guess one of the main focuses then should be calories, is this correct?Dr. Walter Willett: Calories is really important and there’s no single one factor to focus on in diet. In some ways I liken diet and nutrition to an orchestra. You’ve got to have all the pieces there and they’ve all got to be working in harmony to produce you a good sound or incase of nutrition or good health. So the overall amount of food we eat represented by calories is really important, because if that’s more than the calories we’re burning off we’re going to be gaining weight. And that has become probably the Number 1 nutritional issue in the United States is overweight and obesity have gone up. We’re starting to pay huge health prices for that.Calories are important but the quality of the type of calories we get is very important as well. We already talked about the type of fat being really important but the same applies to carbohydrates that carbohydrate is neither good nor bad, but there are good carbohydrates meaning core grain high fiber, forms of carbohydrates and bad carbohydrates, which are sugar and refined starches. Unfortunately in the American diet the large majority of calories aren’t from the bad sources for fine starch and sugar.Also the protein choices make an important difference. It’s not just the protein per say but it’s the protein package. So about the worst is our beef or red meat, because that protein comes along with a lot of saturated fat and cholesterol, and probably some other things in red meat that increase the risk of heart disease and diabetes. But protein in the form of nuts and beans, soy products, vegetable sources of proteins, in other words, in a moderate amount of fish and poultry, that combination of protein can be very healthy, particularly when we use that to replace the large amounts of red meat in our diet.So those are really the important things to consider when we’re talking about calories. The total amount of calories is very important but the source of those calories is equally important.

SPP: Along the same lines here, I was wondering your take on things like grass fed beef or wild cost salmon, do you think that if you stick to more organic naturally raised food products, protein sources, meats, is that going to in the end be healthier? Can you eat more of it say if you don’t eat grain fed cattle and things like that, is that…?

Dr. Walter Willett: We in reality don’t have much directive as it bear on that question, that’s something a lot of people ask, but I suspect that it’s not going to make much difference actually. Maybe a little bit difference with say grass fed beef compared to grain fed animals, but the grass fed beef are still going to be high in cholesterol, because actually the cholesterol comes from the lean part of the meat actually primarily. And that’s going to be just as high in grass fed animals or even higher because the fat content’s a little bit lower. And it may be there’s quite a bit of evidence so that it’s the haeme iron, the form of iron we get from red meat that is causing part of the problem also.

So I think the best thing to do is actually, whether if you’d like to have beef, the main thing is to have it in small amounts. And if we’re having it in small amounts I don’t think it really does make too much difference whether its grass fed or grain fed some of the environmental affects, actually maybe not quite important for our long term survival and well-being that certainly is an important consideration.

SPP: I wanted to take a step back to when you were talking about starches with potatoes and rice, etc. In your, I guess revised food pyramid, you have whole grains as being a very important block of that pyramid. Can you give some examples of how you should eat whole grains throughout the day how much you should eat? For example with lunch, what whole grain should be included to make sure that you’re getting enough whole grains for the day?

Dr. Walter Willett: Sure. As you say whole grains do turn out to be really important because the natural whole grain has not just a lot of fiber into but a lot of minerals and vitamins as well. And when we refine that grain we’re taking away the fiber, we’re taking away the majority of the minerals and vitamins. And so we really stripped the grain of its nutritional value and what’s left is the starch. And it’s become very apparent that that starch, just like sugar, actually has adverse metabolic effects. And particularly it’s a form of grain that’s been grinded up into a refined powder like a flower based product such as bread.

And that form of carbohydrates absorb very rapidly. It makes the blood sugar shoot up, creates a much larger demand for insulin production by the pancreas and in the long run that increases our risk for Type 2 Diabetes and heart disease and other conditions. So the form of the grain is very important and we should be looking for the whole grains. It’s not very hard to do that. The whole grains are a lot more available in stores than they were even 10 or 15 years ago. So that means instead of having white bread having whole grain bread. And it should say an ingredient list or is the first ingredient whole, either wheat or whole or something like that. You want to see that word whole there.

If you’re having rice it means having brown rice instead of white rice, if you’re having pasta or having whole grain pasta instead of white pasta. And I think that those are all pretty easy tradeoffs. So one tradeoff that’s not so easy is if there’s no such thing as a whole grain potato, and so potatoes what we eat is almost all starch. And that does have the same metabolic adverse affects as large amounts of white bread. So keeping potatoes really lowering the diet is another important thing to focus on. And there is no whole grain version of that unfortunately.

There’s no exact amount of whole grain that we can specify. The main thing is if you’re having grains or potatoes, really be converting those two whole grain forms and really trying to minimize the fine form of grains. And what many people find if they’re really just consuming whole grains, weight control becomes easier because that add a large amount of fibers, more satisfying, it stays in our stomach longer and leaves us less hungry between meals.

SPP: And another important aspect of weight control is obviously exercise and on your food pyramid it is the bottom block, which I find very interesting that that’s really one of the I guess first times that that’s been included. Now with exercise I mean times have definitely changed compared to people working in fields and factories, they used to get exercise throughout the entire day, and now most people sit behind desks or have jobs where they’re not getting as much exercise as those that work in the fields.

What does a normal person need to do to make sure that they get enough exercise in a day? What is your recommended amount and how we can, I guess as humans, make up for the fact that we’re now working more sedimentary jobs as opposed to the physical jobs that we used to in the past?

Dr. Walter Willett: Right that’s absolutely true. In the past we didn’t need to think about getting exercise because it was just an automatic part of what we had to do in our day-to-day activities. But now as you say most of our lives involve sitting or driving or watching television or otherwise relaxing in a chair. So we have to really make a conscious attempt to make sure we’ve got physical activity built into our everyday life.

And the amount is in general the more the better but it’s actually surprising how even a fairly small amount of exercise compared to someone working in the fields all day can still be very important for our health. And the amount of exercise, in fact our minimal amount we should be aiming for is about half an hour a day of moderate to vigorous activity. That means like walking fast, just walking slow, but walking fast or running or really being active enough to work up a sweat. And if you’re just walking, if walking is the only part of it then you need to probably walk about an hour a day to get the minimum amount of activity that we really need.

And more is better and also what we’re seeing is its risk too. Do not just aerobic kind of exercise where we walk fast enough to breathe a little faster and work up a little bit of sweat, but also to incorporate resistance training or muscle building kinds of activities into our daily or weekly pattern. And it’s impressive even three or four times a week of resistance training, that means like using elastic bands or weights to strengthen our muscles.

That’s very important as well. In part that’s one way of getting upper body exercise that we otherwise don’t very often get. But using those muscles and strengthening those muscles actually means that the muscles take up blood glucose more effectively and reduce our need for insulin secretion. And so really amazingly just you can see it within hours of being physically actively. Metabolically we’re better off because our muscles are taking up the glucose and reducing our need for insulin. So the important part is to be building into our daily life almost every day some form of physical activity and trying to at least three or four times a week incorporate resistance training as well.

SPP: I actually wanted to really quickly, I know we’re running out of time here, but I wanted to ask you a few questions about things that are very prevalent today in the news. People hear a lot about and I think we can get confused about or I’m not sure what advice to follow. The first thing I was wondering was basically I’ve been hearing a lot about antioxidants these days, drink Pomegranate juice, drink green tea. I wanted to know if you had any insight on why there’s a big push for antioxidants and is this push valid. Does science and research back it?

Dr. Walter Willett: Right that antioxidant area’s been very challenging scientifically to get clear answers on that and that’s I think probably one of the most important reason for some confusion in the general public because people here from little piece of science of antioxidants are important. And the study may come out and be no and not show anything. Part of the reason is that these long term affects of antioxidants are very difficult to stud. They are almost very surely important because are metabolism just in functioning on a day-to-day basis creates a lot of oxidative stress. And the body has a whole complex system of antioxidant defenses to dampen down damage from that oxidative stress.

And that may be one of the reasons why we have so many redundant systems even from protecting us from oxidative damage that it may be that adding some more from Pomegranate or supplements, or something like that, may not make a huge difference because this is so important we already have a lot of built in defenses from oxidative stress. But there is some evidence that oxidative antioxidants can be helpful.

One of the best examples comes from the Physician’s Health Study Trial where over 22,000 men were randomized for, to either beta carotene pills or placebo and there was no change in heart disease or cancer, but after 18 years the men on beta carotene actually had better cognitive function. And that’s really I think a very important finding because it took 18 years for that benefit to show up.