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interview: aviva must
To gain a pound a year, which doesn't seem like much, you would only have to eat in excess of maybe 40 or 50 calories a day.

[When defining obesity] for children it's more tricky. Why is that?

For children it's far more difficult because children are growing, and their heights and weights are changing, but they're not changing in exact concert with each other. For children you really have to reference it to age and to sex, and you have to compare it to some reference population. In the year 2000, the Centers for Disease Control and Prevention released a revision of the growth charts that had been in use for 20 or 30 years. The new growth charts actually, in addition to the height for age and weight for age -- which would be familiar to parents who have had their children for well baby visits and had their child's growth plotted on growth charts -- they added a BMI for age set of charts. That makes it relatively easy to figure out where your child or where any child is, relative to the distribution in the population.

So you can pick up a problem?

So you can pick up a problem. You can see a child might be growing along the 50th percentile, around the average BMI, and then suddenly starts to leave that percentile channel and is gaining weight at a more rapid weight than their height, and you would be able to identify a child who is facing a problem.

I should say that the reference data are based on older data, so we know that the population in the United States has gotten fatter, and the reference data are actually historical.

Aviva Must is a professor of community health at the Tufts University School of Medicine and a scientist for the Nutritional Epidemiology Program at the Jean Mayer USDA Human Nutrition Research Center on Aging. In this interview, she explains the health risks of obesity for both adults and children, and the confusion that results when the media gives the public seemingly conflicting nutrition messages. "People have to eat every day, and they're not sure if they should be eating to lower their cancer risk, or to lower their heart disease risk, or to maintain their weight," she tells FRONTLINE. "If we could only know what thing we should optimize, we could try to do a better job." This interview was conducted on Dec. 19, 2003.

Traditionally, were adult rates of overweight and obesity constant over time?

It has not been constant over time. [It] is my understanding that there have been previous times in past centuries where weights were heavier. But certainly since the first part of the 20th century, weights in the U.S., in any case, were fairly constant. There was some general increase in weights and also in heights in the early part of the 20th century, because nutrition was better. Sometime, probably around the middle of the last century, nutrition was adequate, and I guess in retrospect we would have hoped that things would have stayed constant there.

But what seems to have occurred in the last quarter of the 20th century is that in fact there was an overabundance of food relative to our energy expenditures, and the population started to get heavier, and so you can see that really in the last 25 or 30 years.

It's changed dramatically?

It's changed very dramatically. ... In children, it has tripled over the last 20 to 25 years, from a prevalence of about 5 percent of overweight in children to 15 percent overweight. For adults, around 1960 or so, the prevalence of overweight would have been about 15 percent, and now, it's well more than half, edging up to two-thirds.

So by any standards as public health problem, it qualifies as an epidemic?

It qualifies as an epidemic. For infectious disease epidemiologists, it probably doesn't look exactly like an epidemic because it's not clear that there's a point source. But if you look at the curve, the curve in fact is rising exponentially really in all populations in the U.S., adults and children. ...

Is this problem just American?

No, it's not a problem that's just American, but as in many things, we seem to be leading the way. Our European friends and colleagues are also seeing increases in overweight in adult and pediatric populations. Australia has a very severe problem with overweight, Canada as well. It's really occurring globally, and there are few regions of the world that have not been affected by obesity. In developing countries, you actually see what seems like a contradictory coincidence of under-nutrition and over-nutrition. ...

We've changed in many ways over the last 30 to 50 years. [What are] some of the ways we have changed, which have had impact on this?

Well there've been very important changes in the way family life is organized. As a working mother, I certainly wouldn't have thought that I would see that change, of having a large part of the female population in the workplace as having a potentially causal impact on overweight. But family life has really changed, because when you don't have anybody at home after school, children are not coming home after school, and therefore the sort of free play that occurred after school in the youths or the childhoods of many of the people who will be watching this show, that doesn't happen to the same extent that it once did. You have children going to after-school programs, which may or may not have built-in physical activity.

If you come home after working all day, you're less likely to prepare the kind of balanced meals that we think of as contributing to good nutrition, so there's more eating out, more takeout, more eating on the run, more casual eating. The food companies have done an extraordinary job of making it easier and easier for us to prepare food less and less, either by preparing food at home by putting it in a microwave or in the oven, or by having more grab-and-go kind of eating. From the eating or from the energy intake perspective, things have changed in the U.S.

The number of foods offered in the supermarket has exploded. The density of restaurants and choices seems to be never ending, so that it's very rare that you're in a situation where you can't get something to eat, or even more than that, where something to eat isn't being offered to you as an option. There seems to be a ubiquitousness of the food environment that probably, although it's hard to study, is impacting the amount of food that we eat.

The same is true for the energy expenditure side. There was a recent study in the American Journal of Clinical Nutrition where they quantified the caloric expenditure associated with simple parts of daily living, like vacuuming the rug or scrubbing the floor or peeling the potato, or many of the things that people just don't do to the extent that they once did. In terms of energy expenditure, at all levels there's many opportunities to spend less energy. Simple things like food preparation, where people used to peel their own carrots and peel their own potatoes and chop vegetables, now you have the option of purchasing those vegetables already chopped up, already peeled, so even simple things that would have had small caloric expenditures associated them, have been removed from our options, or at least we have the option not to do them.

One of the things that's interesting about obesity is that if you'd actually do the calculations, the notion that you have to overeat a lot of calories in order to gain weight is actually not true, and it's somewhat surprising to people. To gain a pound a year, which doesn't seem like much, you would only have to eat in excess of maybe 40 or 50 calories a day. Well, if you gain an excess pound a year, that's 10 pounds a decade, or 30 pounds from the time you're 20 to the time you're 50. And that would put you into the overweight or even the obese range.

Small increments of caloric imbalance, just a slight over-intake or a slight under-expenditure, really can give rise to substantial weight gains, so that small things, like there being escalators and elevators that are always easier to find in a building than the stairs, actually may be contributing to small imbalances, and therefore part of the problem that we're facing today. ...

With awareness of saturated fats, the obesity community gets hijacked into cutting out a specific macro nutrient?

I think that there has been a desire and an interest in being able to identify a few of the bad actors, so that we could target them, [the] silver bullet, no more of this food, and then our problems will be solved. There certainly are reasons to decrease intake of saturated fat besides obesity, having to do with heart disease and other problems.

That's another issue that I think clouds it, because people have to eat every day, and they're not sure if they should be eating to lower their cancer risk, or to lower their heart disease risk, or to maintain their weight. I mean, if we could only know what thing we should optimize, we could try to do a better job.

There has been this notion that there are foods and food choices that would make things better or worse, and I do think that the focus on specific foods has taken the focus away from the need for energy balance, and that really it's mostly about calories. There may be some subtle things that happen around the margins in terms of how much carbohydrate or how much fat you're eating, but in terms of energy balance, it's mostly about calories.

Because fat is more dense than calories, there must have been the feeling that if people limited their fat, you were going to get the bang for your buck. Did what happened surprise you?

Well, in a way, it did, because in metabolic studies, if you bring people into a metabolic unit and put them on a very low-fat diet, they actually complain that there's too much food to eat, they can't possibly finish it all, and they tend to lose weight even though in those metabolic studies they're told to maintain their weight. So you're trying to keep them weight-stable and look only at the effect of fat reduction. Based on that, one would think if you went on a low-fat diet, in fact you would lose weight.

Part of the problem perhaps is that the food industry, when they took the fat out, put in a lot of extra carbohydrates. A lot of the low-fat salad dressings are very, very sweet, and actually have the same number of calories or even more calories than the thing that they were substitutes for. And because it's sort of this healthy product, we feel like we have the permission to eat as much of it as we want. I'm sure the people who make Snackwells aren't happy that they've become the symbol of what was wrong in what the food companies did. But the notion that you could eat this whole box of low-fat cookies is really wrong, because that box may contain 1500 calories or so. The fact that it's fat-reduced doesn't mean that it's calorie-reduced. If you're focusing on calories, merely taking fat out is not going to do it if you substitute it with other high-calorie constituents.

If you take something out, you've got to put either water, protein, or carbohydrate back in.

Well, there's no alternative than to put something in, or perhaps reduce the portion size. The food scientists at food companies I know are very capable of doing all sorts of amazing things to food. I think that while there's been an interest in blaming them for the current problem -- I think that they may have a role, in that sense -- but they also are responding to consumer demands, and if we could figure out what it was we wanted them to do, and made it clear, I don't have any doubt that the food scientists working at those food companies could produce it. It's just that we're not so sure exactly how to do it -- although reducing portion size would be a good way to start.

Part of consumers' confusion is that there's more reporting of specific nutrients, good and bad fats, good and bad carbs. Are you surprised by the swings between low-fat diet, low-carb diet?

That's not really new. The low-carb diet that is so fashionable now, I believe, was not very different than the drinking man's diet that I remember my father being on in the '60s. There have always been diets. There was the grapefruit diet, and there was the ice cream diet. There are always diets that focus on something, and many of them work. They work because of the boredom factor, or because they're so highly restrictive that it's just really hard to maintain caloric intake in the face of them, and some of them may, at least in the short term, make it easier to be more restrained in your eating.

I don't think that that's so much new, as perhaps the increasing sophistication of marketing of these different diets. I think that people who understand how to sell have gotten more and more sophisticated, and that may be contributing to some of the consumer confusion and information overload in terms of what they should or shouldn't be eating.

We have obesity happening at the time we have low-fat food and all these diet programs, also at a time when we're having more nutritional advice. Is the message of obesity research being drowned out by all this other stuff?

I think the good news is that people are really interested in health information in general. I think one of the things that has changed over the last few decades is that people really do believe that what they do, that their lifestyle decisions have a long-term, important impact on their health, and that's really a positive change. I think if we could find a way to use that interest to the true end of better health, we would be better served than trying to use it to sell more of one kind of product or to promote one diet book or another diet book.

[How do you contrast the] short-term temporary weight loss diets versus what you're looking for?

[That's the] place that we want the focus to be, because the notion of a diet is that it's something that you start, and something that at some point you'll be lucky enough to stop and then return to your previous habits. Some of the current diets, like the Atkins diet, do deliver rapid weight loss. And people who are on them are very happy to see the pounds shed. The long-term studies, and there have only been a couple, but they're pretty convincing in suggesting that [current diets are] no better over the long term than any of the other diets, and there are concerns about the healthfulness of a very low-carbohydrate diet.

I think that it is important to think separately about dieting for weight loss and eating for life. We do need to eat for life, and we need to find, at the personal level, a way to eat and try to maintain weight. If that were the goal, of weight maintenance in a healthy range, it might promote more healthful eating habits rather than sort of this drastic measures and the short-term thinking.

How important is this as a public health epidemic? If we do nothing, what's going to happen?

The biggest thing that's going to happen is that diabetes rates are going to skyrocket. There was a projection published last summer by the CDC that suggested that for a child born in the year 2000, they faced a 50 percent lifetime risk of developing diabetes, so that means that one child in two, over their lifetime, would become diabetic.

Diabetes is a very, very serious disease. It has tremendous impact on life. It takes very, very careful management. It's an expensive disease. It is associated with cardiovascular risk, with blindness, with amputation, with renal failure, so it will definitely overwhelm our healthcare system. It's a disease that's chronic, so if you get it early, you'll live with it for a very long time. It's likely to be very expensive, but more importantly, it's likely to really compromise quality of life.

Just that one disease.

Just diabetes. And in fact, like the obesity maps that the CDC has produced, they're beginning to produce diabetes maps, and not surprisingly, they're showing a similar pattern. One of the reasons for the focus on diabetes is that it is a disease that is very, very, very closely associated with weight and is one of the few diseases that weight loss can in fact reverse. It's an important disease and it's one that has a lot of impact.

In the pediatric population, type 2 diabetes -- that used to be called adult-onset diabetes -- is being increasingly seen. Where this will lead, it's hard to say, but in some inner city clinics in New York City, I'm told that half of the newly diagnosed diabetes are of the type 2 kind rather than juvenile diabetes or type 1 diabetes, so it's really getting to be quite a prevalent condition in children.

These diseases of adults that are still relatively rare in children, but we do see in children high blood pressure, high levels of cholesterol in association with overweight, asthma perhaps, some orthopedic conditions, and also for children and for adults, a lot of psychosocial burden associated with being overweight. Being an overweight child is not easy. It's still -- even though there [is] some [of] what they call normalization around overweight, where it's getting to be so common that it's not quite the burden that it used to be -- but for very overweight children it is still a stigmatized condition.

One of the things that the prevalence data don't sometimes emphasize is that it's not just [that] there are more and more people who are overweight and obese, but that the subset of that group who are severely obese is growing even more rapidly, so the disease consequences associated with overweight, for adults and for children, are also increasing more rapidly.

What might drive us, as a society, to prioritize this more? What would you tell the family of an obese child are the stakes?

Without wanting to be hysterical, I would tell the family that the stakes are high in terms of impaired health, and that this is really a health condition and not anything else, and one that needs to be taken as seriously as any other chronic disease of childhood would be.

If a child is asthmatic, presumably the family would do what it needed to do to make sure that the household was not fully of asthma triggers. If you have a very overweight child, it's a family issue to make sure that the household is organized to try to bring obesity under control. That means both in terms of what food is in the house and what the family eating patterns are like, and what the rules around eating are like, and all of that, as well as efforts to get everybody in the family to think about physical activity as being part of daily living.

Parallels and differences with smoking? This certainly rivals smoking in terms of seriousness.

I certainly think there are parallels in terms of its seriousness. There are also parallels in terms of the fact that there is a measure of individual control over the behaviors that we think are important.

There are economic things to be gained and lost associated with taking it on as a problem. I think some of the differences are that, as difficult as it was to take on smoking as a public health problem, because it was so much part of life in America, it is a simple target -- simple in the sense that there's one item that you're trying to focus on and remove, and that's tobacco.

Food is a lot more complicated, as is activity. Starting with food, we have to eat and we have to eat pretty much every day, and multiple times per day. You're going to always be interacting with this agent, as it were, where we wouldn't ask somebody who's trying to quit smoking to hold [cigarettes] in the hands, to occasionally take a puff but just not too much, or take a puff but don't inhale. You have to interact with food in order to survive.

And similarly, activity. It's a series of tiny little decisions, When I get off the train and I see the escalator and I see the stairs, I have to choose which one of these choices I'm going to make, and it's probably the difference of, I don't know, six calories, four calories. It's not a big difference, but it's a decision that I'll make two or three times every day, and so if you add up those calories, they will add up. The same [applies] for taking a second helping of something that's on the dinner table. Small decision, one of many you make each day. It seems a little harder from a individual perspective to take on than cigarette smoking, or tobacco use in general.

The other things is that the environment around tobacco changed, and probably really helped decrease smoking rates. As there became fewer and fewer places where one was allowed to smoke, it was harder to maintain your habit. I imagine that some people quit just because it was too much of a hassle to try to find a way to smoke in a workplace where there was no smoking. Certainly their intake or their consumption of cigarettes would have declined.

I think we need as a society to start thinking about the environment and the extent to which it promotes obesity, and thinking about everything from neighborhood design to the design of buildings to the food supply to vending machines in schools, any number of things one could tick off that really speak to the food environment and the activity environment that surrounds daily living.

This isn't likely to be achieved with market mechanisms?

No. I think that we probably need a what we would consider sort of a public health response, and I think the government is going to have to be very much involved in coming up with policy approaches to dealing with the obesity epidemic.

Are they ready to do this? I can't imagine why anyone would be optimistic, given the history.

Well, I have to be optimistic because it's basically my nature to be optimistic, and I think that there is a tremendous amount of focus and interest on this problem that I would never have imagined a couple of years ago. The government is certainly throwing increasingly larger amounts of money at it, probably nothing like they need to....

I'm not sure yet that we know how to make the market encourage the kinds of changes that we need to see, and the extent to which we're just going to have to use regulation. I'm not sure what that balance is. I do think there will be a balance. I do think that the food companies understand that they're going to have to be sincere participants in dealing with this problem. I'm not naive enough to think that they're going to do it on their own without a strong prod from the government and from regulatory agencies.

With children it seems relatively simple.

Yeah, the sorts of things I think we would suggest, or things that would be helpful would be mandatory physical education five days a week in public schools; schools that receive federal funding having to design their campuses so that there are places to play, because there are lots of inner city schools where there is no opportunity for recreation; banning vending machines during school hours; looking at food service and the extent to which the food that's served in school can be more healthful and children's nutrition education that they receive in school can be helpful to their making healthy food choices; not using food for fundraising -- not allowing pouring contracts in schools, where schools partner with companies and say that they'll have the exclusive right to sell Coca-Cola in their schools. ...

Television watching was one of the things that was studied in children?

Yes. It's interesting to me to look back and the early associations between television viewing and obesity. People thought that it was one of those ecological fallacies where you see two things happening at the same time, and it's really not a causal relationship; it's not that television viewing [was] causing obesity. There's now been a lot of work in this area, and in addition to showing in a prospective or longitudinal way that prior television viewing actually results in later weight gains, there's been some prevention work, some really exciting work that was done by Tom Robinson at Stanford, where an intervention designed to reduce television viewing actually reduced rates of overweight.

Is it the television watching itself or the snacking?

It's hard to know exactly what it is about television viewing. There are a number of possibilities. One is that it's very sedentary and so the caloric expenditure while you're watching television is probably not that different than when you're asleep. The pervasive advertisements for food on television may promote eating at times when you're not watching television. Then there's the snacking during television, so that there's a tremendous amount of food that gets eaten in front of television. Of course when you're doing two things at once, you're often not paying attention to them so well, so if you're eating while you're watching television, you may be less sensitive to the cues that you're full. Any of us who have gone to the movies with a big pail of popcorn know that very often you're done with the popcorn and you realize that you've eaten too much, and it's because you were really watching the movie and eating without thinking about the eating part. ...

How long is it going to take [for us to turn around]?

In terms of really turning around and being where we were 20 or 30 or 40 years ago, it may take something on that order, but I would like to think over the next decade we could see that things are changing in a positive direction.

[What's your outlook?]

I do for my research about the health effects associated with overweight, I can't allow myself to believe that we're just going to say, "Okay, we'll just make extra large the way we're going to do things." I'm unwilling to believe that, and I don't believe it. I think that there's a lot of attention being given to it. I think that a lot of it has to do with the health costs and the fact that this will really overwhelm the healthcare system, which we're already concerned about just due to the aging of the population. I have to believe that there are enough people with enough to lose, just in terms of the health aspects of this, where [they are] paying for the health consequences of obesity, that we'll have to respond.

So hard though it is, you think change is inevitable?

Exactly. I think hard as it is, change is inevitable.

[How do] socioeconomic factors [relate to obesity]?

There's really no part of the population that has not experienced an increase in obesity, but it's also true that there are subsets of the population that seem to be taking on an excessive burden of disease. Obesity is associated with poverty and with minority status. Of course those two things are tightly linked, so that minority people are more likely to be poor than non-minority people, but poor whites are also heavier than more affluent whites.

It's like almost every other health condition we can think of. There are disparities, health disparities, and the burden is not equally shared by all parts of the population. In terms of obesity, that may at first seem surprising, since it's really about excess, not about shortage. But food is so cheap in the United States that it's not for money that people are usually shopping. For the choices that one needs to make to eat a healthy diet, those foods tend to be more expensive. A diet rich in fruits and vegetables, which I think all of us in all the various nutrition camps agree is an important part of a healthful diet, those items are expensive. They're highly perishable so there're issues of waste, but they're also, just to buy on a pound-per-pound basis, fairly expensive. They take time to prepare, so if you are working until 6:00 and arriving home as a single parent with your four children, it's not the time that you're going to make a tossed salad where you have to prepare a number of different things.

Fifteen percent of African American women have a body mass index of 40.

Yes, that is staggering, and you start seeing that in teenage African American girls. You start seeing very high rates of obesity, and there are some hypotheses that have to do with stress and depression associated with that. There may be some genetic predisposition. There's a subset of the population for whom pregnancy is associated with very large weight gains, and that may contribute to those rates. But to have 15 percent morbidly obese in any subgroup is very horrifying, and I think that thinking about how to address some of those things from a social engineering perspective is daunting.

An additional complication, if the improvement you start to see is in the affluent population.

Right. That may in fact happen. I think that's one of the reasons why we need to think about systems approaches to obesity, so thinking about the things that we can expose the entire population to, rather than targeting and treating individual people. We have to be doing all of these things simultaneously, because for an African-American woman with a body mass index of 50, that's a person who needs medical attention to help with weight loss. ...

Do you think this concept of energy and calories is too abstract for people?

I think awareness is an important piece. We need to do a tremendous amount of research to try to understand how to get consumers to think in a productive way about weight maintenance and perhaps about weight loss. I think the whole area of consumer behavior, and even understanding what goes into -- if a person even uses a food label, what do they look for? What information could they use?

I've thought for some time that what we need to put the calories on the front of the box and say what the whole box is about, because this notion that it's 2 tablespoons of peanut butter, well, you know, if you take your peanut butter with a knife or with your finger, you don't know how much a tablespoon is. So knowing what the full volume of that bag of potato chips is, might be a better way, [an] additional piece of information other than serving sizes. But we don't know. We really need a tremendous amount more research before we jump in and think that we know how to address that each level, whether it's individual or ecologic. ...

In the U.S. maps, certain areas are definitely heavier than others.

There certainly are regional differences, and places that are more affluent or have a higher standard of living and more highly educated population seem to have slightly lower rates. Colorado has, on those maps, been very slow to join the states that are around it, and that may be because there're so many wonderful opportunities for physical activity. Those are age-adjusted, so that it has to do with where the youth are, and that those are the states that do better, because they are age-adjusted data. But the loss of manufacturing and jobs where there was a fairly strong physical component in the Midwest may be contributing to lower energy expenditures. Manufacturing jobs that do exist are more highly mechanized than they used to be. So it's probably some mix of socioeconomic status, education, physical activity through occupation, that sort of thing.

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posted april 8, 2004

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