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did the low-fat era make us fat?

During the 1990s, the low-fat craze changed the way Americans eat, and yet they got fatter than ever. By 2001, one-third of the American population was overweight. Here, nutritionists Marion Nestle, Walter Willett and Jeanne Goldberg, journalist Gary Taubes, and Dr. Dean Ornish, author of Eat More, Weigh Less debate the reasons behind the disparity between the low-fat message and America's obesity epidemic, and assess whether a low-fat diet is still the way to go.

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marion nestle
Chair, Nutrition Dep't., New York University; author Food Politics: How the Food Industry Influences Nutrition and Health

In the late 1980s, there were two major reports that came out, identifying dietary fat as the single most important change that needed to be made in order to improve diet and health. And the reasons for that message were that some of the fat was saturated. The idea was to reduce saturated fat, but the assumption was that it was too complicated to explain all that, and that if people just reduced their fat content, the fat content of their diet, they would be improving it.

What nobody realized -- or at least I certainly could never have guessed -- was that the food industry would substitute vegetable fats for animal fats in such a profound way, and would also substitute sugars for fats, and keep the calorie content of the products exactly the same. The best example is the Snackwell phenomenon. Snackwell cookies were advertised as no-fat cookies, but they had almost the same number of calories. And in fact if you go to the store today and look at Oreo cookies, they have a reduced-fat Oreo cookie that has, I think, six calories less than the regular Oreo cookie. It's lower in fat but it's higher in carbohydrates.

Did consumers see "low fat" and miss the idea that you could get fat with other things besides fat?

Yes. I think that the "low-fat" message was interpreted as, if you had a product that was low in fat, it was good for you, without thinking of calories. Remember, nobody wants to talk about calories. Nobody wants to. The minute you start talking about fat in its caloric context, then the issue of adding sweeteners back to these low-fat products becomes very obvious. It's the same thing now with the low-carb products. They still have calories. Just because it's low-carb doesn't mean it's healthy. Just because it's low-fat doesn't mean it's healthy. It's still going to have calories, and calories are what counts. …

[Do you still stand by the low-fat advice]?

Yeah. If you're going to lose weight, the easiest place to start is with fat, because it's got twice the calories of either protein or carbohydrate. So it's a great place to begin. The second great place to begin is with soft drinks and those juice drinks, because they add calories and no other nutrients.

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Walter willett
Chair, Nutrition Dep't., Harvard School of Public Health; author Eat, Drink, and Be Healthy

This campaign to reduce fat in the diet has had some pretty disastrous consequences. ... One of the most unfortunate unintended consequences of the fat-free crusade was the idea that if it wasn't fat, it wouldn't make you fat. I even had colleagues who were telling the public that you can't get fat eating carbohydrates. Actually, farmers have known for thousands of years that you can make animals fat by feeding them grains, as long as you don't let them run around too much, and it turns out that applies to humans. We can very easily get fat from eating too many carbohydrates, and the public was really directed to only focus on fat calories, when we really have to keep an eye on calories no matter where they're coming from.

With more fat-free products than ever, Americans got fatter.

Right. The reality is that during this campaign for fat-free and reduced-fat products, actual fat consumption did go down, but Americans got much fatter during this period of time. Now of course lots of things were going on at the same period in time, but I think it's highly likely this focus only on fat calories to the neglect of carbohydrate calories has contributed to this epidemic of obesity. …

What did you notice that seemed to clash with the low-fat dogma?

When we began our studies back in the late 1970s, we expected that we would find a relationship between, say, fat intake and breast cancer, because that was almost an accepted relationship. But as the data started coming in over the years, we just did not find any higher risk of breast cancer among women who consume more fat in the diet. And the same was true for colon cancer and for heart attacks and risk of type 2 diabetes. In fact, the percentage of calories from fat in a diet has not been related to any important health outcome.

Amount of fat has no relationship to coronary heart disease?

The amount of fat had no relationship to risk of coronary heart disease, but the type of fat was extremely important.

So the advice we were getting was not just misleading but dangerous?

Right. The evidence that we accrued really suggested not only that the type of advice that people were getting was not useful, but it actually could be dangerous, because some people were eliminating the very healthy types of fat that actually reduce heart disease rates.

Certain fatty acids can dramatically reduce the incidence of cardiac arrhythmia?

One of the important findings, not just from our studies but several trials conducted by other people in Europe and also some careful animal studies, have very clearly indicated that some types of fatty acids in the diet, in particular the omega-3 fatty acids, can actually reduce the heart arrhythmias that really cause people to drop dead in the street. We call that sudden death. And that's very important because some people were eliminating those critically important fatty acids from their diet because they were told that all fat is bad. ...

If you're American and overweight, won't you be put on a low-fat diet?

If you're overweight and living in the United States, and you go to a hospital and see a dietician, almost for sure, you're going to be put on a low-fat, high-carbohydrate diet.

What's your view of that?

The problem is that that's really the wrong diet for an overweight person. Because the person is overweight, in general they're going to have quite a bit more insulin resistance and much less well able to tolerate low-fat, high-carbohydrate diet.

But fats have twice the amount of calories per gram as carbohydrates. Doesn't it make sense to push the low-calorie diet and therefore a diet low in fat?

There's been a very simplistic idea: Just because fats have more calories per ounce than carbohydrates, we should be eliminating fats or reducing fats to control our total caloric intake, in other words, to help control our weight. What's really important though is how satisfying a diet is, because we have very complex mechanisms that control our total intake of calories, and it's become pretty apparent that if we have a high-carbohydrate diet, particularly high refined carbohydrate, it makes it much more difficult to control our total caloric intake. That's probably because when we eat refined carbohydrates, we get these swings in blood glucose and insulin that lead to hunger between meals; whereas if we have a diet that's somewhat higher in fat, we tend to be more satisfied over the long run.

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Gary taubes
Journalist, author "What If It's All Been A Big Fat Lie?" (New York Times Magazine, July 7, 2002)

The obesity epidemic starts between 1976, say, and 1986. We're fairly confident about that because there're these series of National Health Examination surveys, and we know that in the third NHANES survey, obesity rates are still 14 percent.

Up until about 1980.

Yeah. Basically, up until about 1980, the obesity rates in this country are 12 to 14 percent. And then somewhere in that period between the late '70s and late '80s, they shoot up to 22-25 percent. That's known as the obesity epidemic, and the idea is: What explains it?

From my fat research, I already knew that there were two major changes in the country during that period. One was, high-fructose corn syrup came in as sort of the primary caloric sweetener in America, which was my personal bias. I thought that it was high-fructose corn syrup because I'm allergic to high fructose corn syrup. …

The other theory was that we started pushing the low-fat diets during this period. Starting in 1977, the government started telling all Americans to eat less fat, and starting in the mid-'80s, we started producing these low-fat products that in effect replaced the fat in the yogurt or the cookies or the whatever with carbohydrates. We went from being a country that ate about 40 percent of their calories in fat and 45 percent carbohydrates, to 34 percent fat and that much more carbohydrates. Conceivably, this belief that set in, that carbohydrates could be eaten to excess and wouldn't cause weight gain, that they were both heart healthy and the ideal diet, might have had some effect on weight.

I just went off to try and find out what the answer was. I didn't know when I went in, and the more research I did, the more it became clear that this argument, this hypothesis, the alternative hypotheses that carbohydrates cause weight gain, had validity. Didn't mean it was true. Just meant that it had validity. It could be true, and if it could be true, then the way you would check is to put people on low-carbohydrate diets. You go and look at the low-carbohydrate diet idea, and lo and behold, there's Robert Atkins, who's been pushing low-carbohydrate diets for 30 years, and people swear by them. I had my former experience where I knew that at least for me, I knew it was very easy to lose weight on this diet.

I found out while I was doing my reporting that there had been five studies recently done, clinically controlled trials comparing high-fat, high-protein diets like Atkins to low-fat, low-calorie diets of the kind the American Heart Association was recommending. And in each case, the people on the Atkins diet had twice the weight loss, and their cholesterol profiles, if anything, got better than the people on the American Heart Association diet. So I felt confident saying: Here's an alternative hypotheses that has validity. Here is one set of tests from the hypotheses, that seem to confirm it. Doesn't mean it's true, but it seems to confirm it, and what now needs to be done is more studies. …

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dean ornish, m.d.
Director, Preventive Medicine Research Institute; author Eat More, Weigh Less

The knock on the low-fat diet is that in this long stretch of time while it's been popular, in fact, Americans are getting fatter. We're in a national obesity crisis. So some people would say -- in fact some people have argued -- that the low-fat diet, the popularity of it, has in fact led to this obesity epidemic.

Well, that's silly, for one thing, and it's also based again on a half-truth. And a half-truth is that people say things like, "Well, Americans have been told to eat less fat, the percentage of calories from fat is going down, Americans are fatter than ever, therefore fat is not the problem." Actually, Americans are eating more fat than ever, but they're eating even more simple carbs. So the relative percentage of fat in the diet may be lower, but the actual amount of fat is higher than ever. The goal is to eat less fat and fewer simple carbs, and then you can do so in a way that enhances your health rather than one that may harm it.

What's your best guess as to what has caused this obesity crisis which everyone's very concerned about now? I mean, you're having fat kids and type 2 diabetes, which used to be adult onset diabetes, now people are seeing it in adolescence. It's scary.

Yeah. Diabetes in adolescence has risen 70 percent in the last 10 years. There really is clearly an obesity crisis, but it's silly to just blame low-fat diets as the cause, because they're not. They're part of the solution. The problem is that people get in good-bad ways of thinking: that all fat is good, all fat is bad; all carbs are good, all carbs is bad, when in fact there are good carbs and bad carbs, there's good fat and bad fat, and there's good protein and bad protein. And so an optimal diet is one that's high in the good ones and low in the bad ones.

So let's take fat, for example. In the early '70s and '80s, a number of manufacturers said: Oh, we'll make low-fat foods, but they're very high in sugar: The Snackwell cookies, the Entenmann's cakes and pies and so on. I even had a patient once who was starting to gain weight on a so-called low-fat diet, and I said, "What are you eating?" They said, "Oh, I'm eating just one or two a day." I said, "One or two pieces of these Entenmann's cakes?" "No, one or two cakes at a sitting." They said, "Well, it's low fat. Why not? It can't be bad for me." But it was high in sugar.

But isn't that just the problem? That someone like myself goes into a store or supermarket, and I see something that says "low fat." I think, "Well, of course. I'm going to buy the low-fat whatever it is." But then you think, okay, it means there's no fat in it, and you end up eating a lot of it.

And now the pendulum is going the other way. We're seeing, if it says "low-carb," it must be good for you. So you can buy low-carb vodka, you know, or low-carb whatever.

What people need to understand is that you want to find foods that are low in fat but also low in simple carbs, but not low in total carbs. Low in simple carbs, high in complex carbs. Fruits, vegetables, whole grains, legumes, soy products are good for you. Okay. Low in animal protein, higher in the plant-based protein. It's a spectrum. It's not "all or nothing." And to the degree that you move in that direction, you're going to feel better, you're going to look better, and you're going to lose weight.

So it's still a good thing that there are these low-fat indicators on products in the market?

I think again people need to be more mindful of what they're buying, and to read the labels. …

There was a New York Times magazine article, got a lot of press … "What If It's All Been a Big Fat Lie?" Gary Taubes attacks what he calls the low-fat dogma, and says that diets like yours have led Americans to be fatter, that you're part of the problem.

The reason I spend so much of my time doing science is that the whole point of science is to help people resolve conflicting claims by saying: Show me the data. Now, we've spent 25 years conducting randomized control clinical trials, published in the leading peer-reviewed journals, like the Journal of the AMA, The Lancet, Circulation, New England Journal of Medicine, and so on. And what did we find? That when people eat this way, they lose weight and keep it off. Those who have heart disease were able to reverse it, and we were the first to be able to prove that. And more recently we're showing that even the progression of some of the most common forms of cancer, like prostate cancer, may be improved when people go on these kinds of diets. LDL cholesterol, the bad cholesterol, went down by an average of 40 percent.

Now, when someone like Gary Taubes, who's not a physician, writes an article attacking, I say, "Show me the data." Now, the data that he talks about are purely circumstantial. He'll say things like, "Well, Americans have been told to eat less fat. The percentage of calories from fat is down, and yet Americans are fatter than ever. Therefore fat doesn't make you fat." Now, he knows better, because I've actually debated him as well. And it's a half-truth. The percentage of calories from fat is down, but actually Americans are eating more fat than ever. The only reason that the percentage is lower is that they're eating more fat and even more simple carbs. So the goal is not to say, fat is good, carbs or bad, but to say there are good fats and bad fats, there are good carbs and bad carbs, there's good protein and bad protein, and so an optimal diet would be low in the bad carbs but high in good carbs. …

So something like this article, "A Big Fat Lie," this is just balderdash? This is provocative? This is selling newspapers?

Well, it is provocative. It does sell newspapers. And you know, it tells people what they want to hear, which is also a good way to sell newspapers. It's like that scene in Woody Allen's movie Sleeper, where he wakes up a few hundred years in the future and finds out that chocolate and steak are good for you. …

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Jeanne goldberg
Professor,Tufts University Friedman School of Nutrition

The fat story is really something of a small disaster in its evolution. And I think again there are multiple problems. One of them is the evolution of science. … [In] the original story, cholesterol was a big player, and dietary cholesterol was associated with blood cholesterol. Well, it turns out that dietary cholesterol occurs in so much smaller amounts, its effect on serum cholesterol is not nearly as powerful as the effect of saturated fat. Well, that story, American consumers understood that cholesterol was bad. And the food manufacturers put "cholesterol-free" on every vegetable product they turned out. And if one did it, the other had to do it, because that's competition.

Then we learned, well, cholesterol wasn't the big player. It was saturated fat that really is the big player. From there we went on to types of fatty acids, and so we produce margarines with vegetable oils and the public begin to shift to margarines with vegetable oils. That's fine, and the whipped margarines have less saturated fat than the solid ones. And some of them have water whipped into them, and they have even less fat.

But then we looked and said, "Oh my gosh. In taking out saturated fat, manufacturers are using trans fats, which behave in the body like saturated fat." So the message that got out in the media was, "Butter is better than margarine." And there are headlines from a few years ago that say that. Many, many headlines. And that was one where the consumers just threw up their hands and said, "Oh my God, again they've pulled a dirty deal." It turns out that they both behave pretty much the same. And "less fat, more vegetable oil" is really still the message, which we started with. It's still the same message.

All baked goods would have trans fat?

A lot of baked goods have trans fats, except those that are made with butter, you know, which have the saturated fatty acids. Manufacturers have tried very hard, and are trying very hard, to get the trans fats out of their products. But I can tell you that what we call organoleptic factors, which is a funny, elaborate word for talking about mouth feel and the sensory qualities, and the cookies made without trans fats, to the very sensitive mouth, don't taste the same. Some people will tell you they do, and those who are really super-sensitive tasters will tell you that they don't.

I think a lot of this issue begs the question of a concept that Americans have a really hard time with. It's that concept of moderation. If we could eat two cookies and move on, we'd need a lot less of what I call this jiggering with the food supply. But we don't. We want to eat a lot of things, and a lot of what we eat, and a lot of variety.

And that's the other part of the fat story, which is that fat does have twice as many calories per gram as carbohydrate. So about 10 or 15 years ago, somehow we got this notion that: Aha. If we take the fat out of foods, we will be able to reduce the total caloric intake, and people will be able to control their weight. And so industry got very busy making low-fat, reduced-fat, fat-free products. And they flooded the marketplace and they flew off the shelves. And guess what? A lot of them weren't very good, and so they died on the vine very quickly. The ones that were good, people ate in excess. They didn't look at the portion size. They didn't look at the calories. They just ate them. There's no free lunch. There were calories. Guess what? People didn't lose weight. They got frustrated and went back to eating the food they liked in the first place.

What did [people think] when they saw "low fat, fat free"?

"Low-fat, fat-free, good for me. These have got to be good for me if they're marked low fat." Of course in many of the foods, if you looked at the label of the regular and the low fat -- and you can still do this -- the caloric difference isn't all that much. In some cases it's more significant than in others, but the issue is that if you take out fat, you got to put something in. That something, surprise surprise, has calories. It's most likely carbohydrate, a little bit of protein, and those both have calories. So you can't continue to take everything out and have some flavor and texture left, and the calories in many of those foods were not very different. …

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posted april 8, 2004

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