Eat, drink, and be healthy

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Coming up on Harvard Chan: This Week in Health…

We discuss two decades of nutrition science with one of the leading experts in the field.

{***Walter Willett Soundbite***}

In this week’s episode we sit down for an in-depth conversation with Walter Willett, former chair of the Department of Nutrition here at the Harvard Chan School.

He’ll speak with us about the updated version of his new book: Eat, Drink, and Be Healthy—which compiles decades worth of evidence about the components of a healthy diet.

Plus—Willett weighs in on the issues that will dominate the nutrition field in the years to come—including obesity—and how climate change will force us to change how we eat.

{***Walter Willet Soundbite***}



Hello and welcome to Harvard Chan: This Week in Health..I’m Noah Leavitt.


And I’m Amie Montemurro.

This week we’re sharing an in-depth conversation with one of the world’s leading nutrition experts: Walter Willett.


Willett spent 25 years as the chair of the Department of Nutrition here at the Harvard Chan School.

During this time, he was a leader in the field of nutritional epidemiology—helping establish the basic principles of healthy eating—while also highlighting the dangers of things like trans fats and sugar-sweetened beverages.


And Willett—along with co-author Patrick Skerrett—have collected this research in their book Eat, Drink, and Be Healthy.

They just released an updated version—building upon the original book first released in 2000.


I sat down for an in-depth conversation with Willett to talk about the book, what’s changed in nutrition science since it was first released, and the issues that will dominate the field in the years ahead.

I started our conversation by asking him why the time was right to release an updated version of Eat, Drink, and Be Healthy.

{***Walter Willett Interview***}

Walter Willett: I think one of the important elements of this book is that eating in a healthy way is not a sacrifice in terms of pleasure and enjoyment. And for that reason, in this book, there’s about 80 recipes included that give some examples of how we can put this into practice. I asked about 20 of my colleagues who are chefs and people engaged in the food service to contribute some recipes. So this is something that could be an adventure and invite people to try some new things. And definitely, most of it, maybe all of it can be more enjoyable and interesting than the sort of mashed potatoes, gravy, and roast beef that I grew up with.

The reason for releasing the first edition of Eat, Drink, and Be Healthy back in 2000 was that we had published many reports in scientific literature about specific aspects of diet and health outcomes. But these were in dozens of different journals. And it would be really hard for anybody, including even people I was working with, to put together the pieces and really see the big picture that was emerging. And the picture was that diet was incredibly important in many ways for promoting health and well-being– no one factor, no silver bullet. But together, all the pieces were adding up to having a huge beneficial impact.

Noah Leavitt: And so in the last 17 years, nutrition science, or knowledge of healthy eating, have come a long way. So what do we know now that maybe we didn’t know then about some of the foundations of healthy eating?

Walter Willett: The context was back in the 1990s and into the early 2000s…The conventional wisdom was that the primary target for nutritional advice and change should be on reducing total fat in the diet, which meant load up on carbohydrates. And this was advocated by many people in the nutrition community. The food industry responded to that, created many low fat, high carbohydrate, high sugar products. And that was thought to be a good thing. But our data was really telling us another story; that this high intake of carbohydrate, particularly refined starches and sugars, had adverse metabolic effects. And that was showing up as increased risk of cardiovascular disease, and diabetes, and other conditions, as well.  So our book, at that time, was in some ways, a bit revolutionary. It was definitely out of the mainstream to be talking about healthy fats being good for us and being careful about the type of carbohydrate at the same time. This was based not just on one single study. It was based on many pieces of evidence.  So we were quite confident that this important. This was really representing the right direction for a healthy diet. Since that time during the last 17 years, a lot more information has become available that has supported this conclusion. So in some ways, the most important part of this book is that it’s not that it’s entirely new and revolutionary. It’s really that we were on the right track. We have a lot more evidence that that was important. And there are more benefits that we’ve seen emerge as well.

Noah Leavitt: And are we still feeling the effects– in terms of the American diet as a whole, are we still feeling the effects of that push to go low fat? Is there still work to be done in order to get people to understand that one, fats can be healthy and beneficial, and that two, you need to be careful about the kinds of fat you’re choosing?

Walter Willett: There’s still work to be done. These changes in direction occur slowly. And there are still even professionals steering people, especially overweight people who often can least tolerate high amounts of carbohydrate toward that direction of diet. So I think it’s important for people to have some basic understanding. What’s more important than taking care of our own bodies or the bodies of our family and our friends? And there are still many people that are not taking advantage or able to take advantage of the best information we have at this point in time.

Noah Leavitt: Have we seen progress in the U.S. in terms of people starting to consume more healthy fats and maybe less of the unhealthy fats? Trans fats have obviously been a huge issue. So is there progress in that area at all?

Walter Willett: We’ve had some major progress on the dietary fat front. Some of this is because people have become aware and are making better choices. But also, in parallel with informing the public, we were pushed hard on manufacturers to improve their products. And some of the levers were banning trans fats in restaurants, putting trans fat on the food label. And in most cases, the manufacturers who have removed trans fat have not just loaded our foods up with saturated fat, but actually replaced those trans fats with healthy fat. So when we look at the fat composition of our food supply today, in 2017, it’s actually much better than it was in 2000.

Noah Leavitt: And so you mentioned at the beginning that one of the benefits of this book is that it does compile all of this nutrition research into one place. And that seems, to me, to be really important at a time when there is a lot of conflicting news information about fats. Butter is back, butter isn’t back. So how could consumers maybe use this book to maybe learn some tips and learn ways to build a healthy diet for themselves?

Walter Willett: It is really important, I think, to put all the pieces together. There’s no single study which will give you the right answer. There is no magic bullet in the diet, or a magic food, or vegetable, or one single dietary factor that will make you healthier. On the other hand, if you don’t do it, it really comes down to disease and suffering. In some ways, I make the analogy with an orchestra. A healthy diet is like having all the pieces and having them in balance. And it is really important to look at that whole picture, make sure our diets are composed of a balance of healthy aspects of diet. And by doing that, you can really have a full impact, the benefits of healthy eating.

Noah Leavitt: It seems like one of the trends in the last few years has been this kind of growing awareness of the dangers of sugar and sweetened beverages. There are more soda taxes taking hold. So over the last decade or so and longer, what has the evidence started to show us about the dangers of these sugar sweetened beverages? And the second part of that, has there been any progress in that area, in terms of producing consumption?

Walter Willett: This has been an important area. And it’s part of the whole picture of carbohydrate quality. And sugar sweetened beverages are turning out to be one of the most important aspects, detrimental aspects of carbohydrates in our diet. It’s partly because we can consume so much sugar in such a short time. In the standard 20 ounce serving now of a soda, there’s about 17 teaspoons of sugar. So it’s a huge amount, all of a sudden. And back in 2000, we had some suspicion that that was not a healthy thing to do. But we’ve really, since that time, developed a very solid basis of documenting the adverse effects of sugar sweetened beverages on both weight gain, diabetes risk, cardiovascular disease risk, and some other adverse health outcomes as well. So we can be much more specific about the adverse effects. We’re much more strongly based. And because of that, as you mentioned, we’ve been able to develop soda taxes in some places, made great progress eliminating soda from schools. Overall, soda consumption is down about 25% in the United States, which is a huge step forward. And it looks like we’re already seeing some benefits in reductions of type 2 diabetes. So this has been an area where we have made some important progress.

Noah Leavitt: And so you touched on this idea of carbohydrate quality. And you made that orchestra analogy. So is the conventional wisdom now not to demonize any one type of food, carbohydrate or fat, but more that you need to make quality choices in each of these categories?

Walter Willett: I think that’s a helpful way to look at it, to really focusing more on the quality than just one category is good or bad for us. That seems to be what the science is telling us, that high quality carbohydrates would be whole grain, high fiber forms of carbohydrates, particularly if they’re consumed intact, not milled into fine, powdery flour. And on the other hand, finely milled white flour is rapidly absorbed and converted to blood glucose. It has many adverse metabolic effects. And of course, sugar also has adverse health consequences as well. That refined starch is often overlooked. Focus on sugar is important, but we can’t forget and get too out of balance again, that it’s only part of the carbohydrate picture. Potatoes also are very rapidly converted to blood sugar. And small amounts, now and then, no problem. But I grew up in the Midwest, where it was normal once or twice a day to have that white mountain on your plate. And that definitely has adverse effects related to higher risk of type 2 diabetes and weight gain.

Noah Leavitt: So I want to spend a little time talking about obesity. And one of the things that you pointed out that I thought was interesting was that when it comes to obesity, we’ve seen great progress when it comes to children in terms of the obesity rate flat-lining a little bit. But it’s increasing among adults. So why do you think we’re seeing this disparity between children and adults?

Walter Willett: Rates of obesity have really increased since the early 1970s in both adults and children. We’ve paid a lot more attention to the childhood obesity problem for a couple of reasons. I think we are responsible for children in ways that are not exactly responsible like we are for other adults. There’s more political consensus that we need to pay attention to children. And maybe, I think also, it’s easier to blame somebody else– kids, not ourselves, for problems that we have. And for all those reasons, we’ve put in many places a lot of effort, big time effort into schools. So we’ve banned sugar sweetened beverages in schools. We’ve, in many places, paid more attention to what children get. Pediatricians have become much more proactive about advice on sugar sweetened beverages and diets in general for children. And we’ve neglected that adults are at least as big a part of the problem in terms of weight gain and the health consequences of weight gain. And we’ve given less attention to adults. So it’s been encouraging with all that effort on children that it looks like we’ve blunted the obesity epidemic. And some places, obesity rates in children are actually starting to go down. In communities like New York City and Cambridge, where there’s been a more intense effort, rates are still too high. But it looks like we’ve bent the curve in those areas. But without letting up on efforts for children, we really do need to focus additional efforts on adults. The basic problem is that that really almost invisible pound or two gain in weight per year, which is typical of Americans from age 20 to 50 adds up to a huge weight gain that has many serious, adverse consequences by midlife and later.

Noah Leavitt: And so knowing that in terms of the cumulative total weight gain, does that offer an insight into ways to maybe address the obesity epidemic? That it’s not a short term issue. It can be an issue over 20, or 30, or 40 years?

Walter Willett: The fact that this creeping weight is so important does tell us we really do need to change our approach in medicine and public health as to how we deal with weight gain in adults. All too often, recommendations don’t kick in until you’re already obese or overweight plus complications. You already have diabetes, hypertension. And that’s not the right way to be dealing with this problem. The problem is dealing with a healthy diet and active lifestyle, even during age 20s, that physicians should be counseling. Physicians and other health care providers should be counseling their patients about diet and activity levels during that period of time, taking action at the first few pounds of weight gain, not waiting until somebody is overweight or diabetic and having complications, because oftentimes, it’s much more difficult to be active once you’re overweight and have diabetes or other kinds of joint problems, other kinds of complications of being overweight.

Noah Leavit: And you’ve touched on it there, but obesity is such a large and complex problem. But are there key areas that you think that maybe we should be focusing more on going forward in the next few years or so?

Walter Willett: It’s not a single factor. And it’s not entirely within the control of individuals. But that doesn’t mean we should just throw up our hands and ignore it, because individuals can make an important difference by their choices of food, by how they integrate physical activity into their daily life. For example, we have seen that the biggest single factor is sugar sweetened beverages. And many people can make a big difference in their weight just by eliminating sugar sweetened beverages. Highly refined carbohydrates, for many people, also add to that problem, whereas whole grains, fruits, vegetables are related to less weight gain. So it’s shifting toward what we understand, for other reasons, is a healthy diet. The quality of the diet has an important impact on weight gain. But we can make this a lot easier for individuals by making healthy food available and the default in first of all, schools for children, but work sites. And employers are starting to get this message now too, that it’s a double win both the employer and for the employee to have healthy food and avoid weight gain and the consequences of it.

Noah Leavitt: So I think one of the interesting trends that’s really gained awareness in recent years is this idea that our diets are also increasingly linked to climate change in the environment. So what do we know now about the links between our diets and climate change, I guess by in a both positive and negative way?

Walter Willett: The links between our diets and climate change are so important that I, in this new edition of the book, devoted a whole chapter to that topic. I think climate change is something that’s occurring far more rapidly than any of us thought 30 or 40 years ago. We thought it would be something that would be experienced in hundreds of years or 1,000 years, but we’re seeing that year by year, the temperature going up. We’re seeing the consequences of climate change already– flooding, drought. And this will be picking up at a more rapid pace, even if we didn’t make any changes. But if we look at the picture, we’re on track to greatly exceed what are agreed upon as the international limits of what we should be doing in terms of controlling climate change. And food choices do have an important impact among the other factors that contribute to climate change. In particular, production of red meat is an extremely important source of greenhouse gases, both methane and carbon dioxide. On the other hand, more plant based diets have much lower impact on greenhouse gas production. And as it turns out, those same changes shifting from a high meat, particularly red meat diet to a more plant based diet will not only reduce climate change, but have important health benefits as well. So there is a double win here.

Noah Leavitt: And what are some practical changes people can make to their diets? I mean obviously, reducing red meat is probably a good start. But are there other changes people to think about making that would not just benefit the environment, but also– it would probably benefit their health as well.

Walter Willett: In addition to red meat, probably the next biggest environmental footprint comes from dairy foods. And the current dietary guidelines actually recommend three servings of milk per day or milk equivalents, in terms of cheese. That’s a huge amount. It’s actually almost double what we’re currently consuming. And nobody in the Department of Agriculture’s paying serious attention to this. In fact, Congress passed a law saying that the Department of Agriculture actually can’t mention effects of diet on climate change in their guidelines. And so basically, the report of the scientific advisory committee was censored. So in some sense, this chapter in my book is uncensoring a bit what the scientific review committee concluded about diet and climate change. So instead of red meat, think about plant based sources of protein. It turns out nuts are one of the healthiest possible protein sources. And that switch from red meat to nuts can make a huge impact on both health and climate change. But there are lots of other alternatives– soy based sources of protein and other forms of legumes or beans need to be considered more often. The consumption of beans is very low in the US diet now. But they can be prepared in many really tasty, interesting ways. I’m afraid too many of us grew up with that can of baked beans, which is pretty dismal a meal, if you’re just having that straight. But there are hundreds of different kinds of beans. Almost every traditional culture has found ways to make them really tasty, interesting, and an important part of a healthy diet. So we don’t have to make that step all at once. But step by step, shifting more toward these healthier sources of protein will be good for our family, good for our own body, and definitely good for the climate and Earth’s health, as well.

Noah Leavitt: On some level, in order to get traction in this area, it probably has to go beyond individual choices and really get it addressing some of the government subsidies that promote dairy consumption, beef consumption. So is that really one of the root causes that needs to be addressed?

Walter Willett: Certainly, it would be much more helpful, if we had policies that promoted a healthy, plant based diet food system, rather than the kind of subsidies that we put into a food system that supports high animal products, especially beef consumption. One fact I find particularly interesting is that if we look at how our grain production is used domestically in the United States, all the grain that we use domestically, about 1/3 goes to conversion to ethanol to fuel automobiles. If we just drove automobiles that were a little bit more efficient or smaller, we could get rid of that. About 45% is used to feed animals, which make us unhealthy, particularly when fed to cattle. And about 15% is used for manufacturing, which basically means high fructose corn syrup, for the most part. And only 10% is actually consumed by humans. So we’ve created a food supply that is really incredibly destructive to our planet, to our environment. And also, it’s destructive to human health, as well. It’s hard to imagine that we could have created something that’s been so destructive.

Noah Leavitt: So the previous almost two decades seemed to really focus on the scientific consensus around dietary fats, and low fat is not best, and really building that consensus of what a healthy diet is. Looking forward over the next two decades, what do you see will be the dominating issues of nutrition science? Is it climate change sustainability? Are there other issues on the horizon that you think people should be focusing on?

Walter Willett: I think everything we do needs to be looked at through the lens of climate change and sustainability. If we don’t have that, the world our children and grandchildren will experience will be very dark and dismal world with a lot of what we enjoy and expect really severely damaged. But given that we have to do things within the context of sustainability, I think the biggest challenge is actually implementing what we know already. We do see, and have done several published analyses that we could prevent about 80% of heart disease with diet and lifestyle by essentially adopting this simple package of factors that are healthy and a diet, moderate, physical activity, not smoking. We could have a dramatic impact. But only about 3% of the participants in our study were following that healthy package of lifestyle and benefiting from this huge reduction in cardiovascular disease risk. And the same applies to several forms of cancer. It looks like we could, with a healthy package of diet and lifestyle, prevent about 90% of type 2 diabetes. So the potential impacts are huge. But the gap between what we could achieve and what we’re achieving now by diet and lifestyle is so huge that a lot of our efforts, I think, have to be focused on basically implementing, translating what we do know into practice. And there are many ways of doing that. Part of it is just conveying information and knowledge, but also creating an environment that supports and makes these healthy choices easier, more affordable. And that’s going to involve almost every institution that we experience– our work site, our schools, our cafeterias, our food services. So this is a big challenge. But we are slowly making progress. We just need to speed that up.


That was our interview with Walter Willett about nutrition science—and his updated book Eat, Drink, and Be Healthy.


Willett talked a lot about the foundations of healthy eating—as well as the importance of eating sustainably in a way that benefits the environment.

For information, you can always visit the Nutrition Source—at

We’ll also have some information on our site,


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October 12, 2017 — In this week’s episode we discuss two decades of nutrition science with one of the leading experts in the field. Walter Willett, former chair of the Department of Nutrition, recently released an updated version of his book Eat, Drink, and Be Healthy, which compiles decades worth of evidence about the components of a healthy diet. During an in-depth conversation with Willett, we talk about what’s changed in nutrition since the book was first released in 2000 and the topics that will dominate the field in the years to come—including obesity—and how climate change will force us to change how we eat.

You can subscribe to this podcast by visiting iTunes, listen to it by following us on Soundcloud, and stream it on the Stitcher app.

Learn more

Visit the Harvard Chan School’s Nutrition Source

Tips for sustainable eating (Harvard Chan School Nutrition Source)