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interview: joseph hotchkiss
If you want to reduce the caloric content of a food, you remove the fat.  But of course you have to replace that with something else.

... [Is] all food is processed?

All food is processed to some extent. The processing of food does not inherently make the food of less or more value. You have to take it on a case-by-case basis. The most popular fruit consumed in the U.S. is actually tomato. And the reason for that is that we eat huge amounts of tomato as processed tomatoes -- as pizza, spaghetti sauce, ketchup -- all of those kinds of processes making tomato widely consumed and not destroying much of the nutrition of it, actually.

[What] are macronutrients?

Foods can be divided up into four basic macro components: water perhaps being the most important, whether it's there or absent, carbohydrate, protein, and lipid or fats. So all foods are made of some mixture of those four components, plus some other trace nutrients -- flavors and those kinds of things.

If you asked most people what was bad in food, they'd say fat.

I think over the last few years they would. But if you'd gone back 20 years, I don't think it would have been fat. It might have been carbohydrates. If you'd gone back a little bit further, maybe into the 1960s, it would have been food additives. So our attitudes about these different components change over time.

Joseph Hotchkiss is chairman of the Department of Food Science at Cornell University. He has also served as a public health fellow at the Food and Drug Administration, and is on the FDA's Food Advisory Committee. In this interview, Hotchkiss discusses basic food chemistry and details the four basic macro components of food: water, carbohydrates, protein and fats. "Whenever you take out something in a food product, you have to replace it with something else," he explains. He also describes the challenges of trying to replicate the sensory attributes of certain food products, as well as potential unintended health consequences when creating low-fat or low-carb foods. This interview was conducted Dec. 9, 2003.

What would concern us about fat?

Fat is more than twice the caloric density of the other components. That is, on a weight basis, it has more than twice the number of calories. So if you want to reduce the caloric content of a food, you remove the fat. But of course you have to replace that with something else.

There is also concern with fat as a cause of coronary heart disease.

Certainly diet is associated with chronic diseases, atherosclerosis and cancer both. You can make very strong linkages. There are diets that seem to increase the risk of these diseases, and diets that seem to decrease [the risk]. The fat connection to atherosclerosis and coronary diseases is very strong. It's just that when you get down to the very fine analysis, we have some debate.

Animal fats versus vegetable fats?

Probably for most of human history, the most common fat consumed in a variety of ways was animal fat. Lard is animal fat. It has a number of properties that worked very well in foods, but there was concern over the fact that it's quite saturated in its cholesterol content, that we moved away from lard as an edible fat. And so it's a very minor edible fat nowadays.


Yes, butter being the fat separated out of milk, also an animal fat. A little bit different composition than lard, and certainly a different flavor. As we moved out of lard, we moved into butter. Butter, as I said, is also a saturated animal fat, also contains cholesterol, and over time this lost favor as well.

What characteristic of these fats is important? That they're solid?

Well, there are important properties in two areas. One is a nutritional biological activity. Another is a functional activity in foods. Solid fats, for example, have important characteristics for some kinds of foods, particularly for bakery products. Every good chef knows that you need to use a solid fat and make a pastry at a very cold temperature so the fat stays solid. That's a functional property that we have used lard and later butter and now some kinds of hydrogenated vegetable fats for.

Why are these fats solid?

Animal fats come from systems that can control their body temperature and have an elevated temperature. They're not dependent on the surroundings. So they can have a more saturated kind of fat, because at the body temperature of 98 degrees for example, in humans, the fat becomes liquid. The fat must be liquid in a living system. However, plants and some kinds of marine animals, some kinds of fish particularly that do not control their own temperature, their fats would all go solid at their body temperature and they would cease to live. So both plants and cold-blooded fish have to have an unsaturated liquid kind of fat system.

Here is, for example, olive oil, a plant fat. [It] comes from obviously the olive seed. It is a liquid because it comes from a plant source. On the other hand, if you take butter, [it] comes from an animal system. At room temperature it is a solid. Likewise, corn and soybean oils and canola oil in this case, at room temperature are liquids. The only real difference between a liquid and a solid fat is temperature. This fat will go solid if you lower the temperature enough. So at room temperature, plant and fish oils tend to be liquids, whereas animal fats tend to be solids. Not at body temperature, though. Everybody's fat has to be liquid at body temperature.

[Does that explain why nutrutionists prefer vegetable oils?

Yes. They are liquids because they are unsaturated. And the epidemiology and most of the laboratory research suggests that unsaturated fats reduce serum cholesterol, and serum cholesterol is clearly a risk factor for atherosclerosis and arterial disease. ...

What can't you do with liquid vegetable oil?

Well, you can't use liquid vegetable oils in some baking applications because at room temperature they're liquid and don't impart the physical properties to certain baked goods that you would expect. Flaky crust, for example. Vegetable oil will not make a flaky crust or a croissant. You need a solid fat for that.

That's a pretty serious problem the industry faces?

Certainly it's a serious problem. If you can't deliver the kind of texture that people are expecting in a product, and you're in the business of trying to sell that product, you have a problem. …

The problem the oil industry faced as it went from animal fats into vegetable oils is just that vegetable oils are liquids. And at room temperature, liquid oils do not perform adequately in some categories of products. They had to find a way to make a liquid oil into a solid fat, and the way that you do that is by hydrogenization. You essentially add hydrogen to the double bonds, to the chemistry of the oils, and that makes them a solid.

Like for instance margarine?

Like margarines. Like different baking shortenings. Those are all liquid oils that have been hydrogenated to make them become solid at room temperature.

On the face of it, it looks like you've [solved] the problem.

Well, that's a lesson in what you do. There are always unintended consequences. One of the unintended or unexpected consequences of this is, you change the geometry of a small portion of the fat. You changed it from what we call a "cis" geometry into a "trans" geometry. And it turns out that we have some evidence that that trans geometry is not as healthful as we thought.

In what are called trans fats?

Trans fatty acids. Yes.

[Are those] baked goods made with solid vegetable margarine?

Yes. Unquestionably.

So have we improved the health of the population or not?

I think a lot of people believe that we have not improved the health of the population, and that while we can't immediately shift out of this kind of trans fatty acid thing by labeling them, we will inform the public and the public will vote with their dollars, and they will look for products that have low trans fatty acid contents. And the industry will respond by developing those kind of products.

So it could go back to saturated fat?

Certainly it could. As a matter of fact, I think the latest data is that butter consumption, for example, is up. There are a number of new kinds of butter products on the market. For example, there is even a light butter now on the market, which has a 50 percent caloric reduction, which is almost an oxymoron, but they figured out how to do it.

Talk about the low-fat trend. How do you make products lower in fat?

Whenever you take out something in a food product, you have to replace it with something else. Even if you take it out and say, "I'm not going to replace it with something else," you're really increasing the amount of whatever the other components are. Remember, we have only really four components to work with, in a general sense here. ...

[For example, with margarine], we have a product that is, in essence, normally, 100 percent fat. So you have only one component to take out. If I take out half of the fat and don't replace it with anything, I really haven't taken out anything. So I have to replace it with something. The best thing to replace it with is water, because water has no caloric content.

So you can take this product and take out half of the fat and replace it with water -- [it] takes some technology to do that. Thereby you lower the fat content by 50 percent; you lower the caloric content by 50 percent. And you can see this in a product simply by melting it in a microwave oven or something, and watching the water which will come to the bottom.

Why can't you do that in all cases?

Well, when you do this with this product even, you sacrifice some things. For example, this product does not fry very well, in my opinion. People like to cook things in butter, but essentially you're adding butter and a lot of water. When you [add] oil and water to a fry pan, it can cause problems. It doesn't behave in exactly the same way. But as a spread, I think it's a very reasonable and nice solution.

[What about] ice cream?

Yes. Low-fat ice cream has been available, and a number of them are on the market. If you take out the fat in ice cream, you have to add something back. You can't just simply remove the fat. It's not as easy as that. You have to have something back in there that will have the functionality of fat in ice cream, particularly the creaminess, the mouth feel of the ice cream. If you don't, you have a product called ice milk, which has never been very successful.

So in order to make ice cream, you typically will replace the fat with either one of the other three components, and most often that component is a carbohydrate. Could be a protein as well. ...

What is industry doing? Trying to attract people to new products, or responding?

The food industry is very strongly consumer-driven. In other words, the food industry's goal is to try to find out what the next thing that the consumer will be interested in is, and then produce that thing, in hopes that the consumer will embrace their idea. The food industry really tries to find out what consumers want, and supply that product to them. Many people think it is the opposite. They think that the food industry develops a product and then tries to create a demand. But in reality, it works the other way.

People wanted low fat because they were worried about health and overweight?

Yes. Clearly, weight was a serious concern, [it] still is obviously, even more [of a] concern now in the U.S. population. The food industry responded not only with low-fat products but with a range of reduced-calorie products and a whole series of brand names -- Healthy Choice, Snackwells are a couple that come to mind -- in hopes that the consumer would embrace those products. The consumer did embrace those products for a period of time. That interest seems to have waned. Those products are on the decline, and now the industry's looking for new products.

Obesity went up faster in the low-fat era than ever before. Doesn't make much sense.

Well, clearly the move to low-fat products -- the facts are, it did not reduce the weight of the U.S. population. Why that is, is not quite as clear. I think in part it is that people consume more of a low-fat product than they would a higher-fat product. In reality, it's not necessarily the fat intake but the caloric intake that affects weight.

So just because something was low fat didn't mean it wasn't fattening?

That's absolutely true. Just because anything was low in fat doesn't make it a low-calorie or non-fattening product. But this is quite confusing [to] a lot of people. If you ask a group of people whether they would more likely gain weight taking in 3,000 calories in carbohydrates or 3,000 calories in fat, they almost all say, "Well, certainly you would gain more weight taking in 3,000 calories as fat," when in reality you probably would have an equal weight gain in both of those categories.

Fat, carbohydrates, and proteins, in the body they become one type?

The only real energy source that the body can use directly is glucose. So everything that you're going to use for caloric value has to be converted into that same simple sugar, glucose. The real issue is: At what rate are those things converted into glucose, and at what efficiency? It turns out that the efficiency for fat is more than twice as high, on a weight basis, than it is for carbohydrate or protein, which are pretty much equal.

So a low-fat approach makes sense, really?

A low-calorie approach always makes sense. A low-fat approach may or may not make sense, really.

What [are] carbohydrates?

Carbohydrates is a word defining a wide variety of different kinds of materials that are in foods, from the simplest sugars -- fructose, glucose -- all the way up to extremely complex carbohydrates, such as those extracted from seaweed or other sources, some of which are digestible by humans, some of which are not digestible by humans. Wood -- cellulose -- is made of the same repeating unit as starch, glucose. It's just put together a little bit differently, so biologically we cannot use it. It passes on through us. Starch, on the other hand, we can break down and we get caloric content out of starch.

Some people have said nasty things about certain types of carbohydrates.

Well, certainly. The pendulum is swinging away from fats as being bad guys -- fats are gaining stature, actually -- towards particularly simple carbohydrates, sugars, which are now being thought to be the bad guys in our weight gain. My prediction is that some time in the future, the pendulum will swing away from carbohydrates towards something else. ...

What do you think of [the low-carb theory]?

I think that it would be nice to have such a simple solution to a major health issue. But unfortunately, simple solutions to large societal problems don't seem to materialize, and I don't think the issue is quite that simple. I personally ascribe to the old nutrition philosophy that there are not necessarily bad foods, but there are a lot of bad diets and bad use of foods, and that this is a idea in which caloric intake should balance better with caloric expenditure. We wouldn't have the problem if we ate a mixed diet.

As an industry, [it] doesn't matter whether this is right or wrong, you have to respond.

Exactly. If you want to stay in business, you've got to respond. It's not the industry's job to decide necessarily what's right or wrong. It's the industry's job or goal to understand what the consumer believes is right or wrong, and then provide the consumer with those products that meet their needs.

What is industry thinking about now?

Right now they're all thinking about how to reduce the carbohydrate content of their products. Of course that means increase the other two major components or maybe three components, if you can replace some of that carbohydrate with water. So you have to increase the protein and/or the fat.

Why are they thinking about this?

Because that's the way they see the population, the consumer, going. They see the consumer as being very interested in low-carbohydrate food, so they're working hard to provide them low-carbohydrate foods, because that's what they want. That's what the business they're in. …

Rightly or wrongly, low-carb diets, this phenomenon will have commercial consequences?

[It] already has. Even Atkins has a whole range of products out there. Even though he's dead and gone, his legacy moves on. You can go into, I think, most any grocery store and buy Atkins brand, whatever kind of product that fits the Atkins diet mold. So certainly it's a commercial venture.

[What's the] technical problem [in] taking the carbohydrate out of food?

Back to this theme of taking something out, you have to replace it. The choices to replace it are water, protein, or fat. Of those three, for many products, maybe the majority of products, the replacement material will be protein, so people are working on ways to make protein behave as though it were carbohydrate to get it out of products.

Is protein the last untouched component?

I think that's right. You don't want to say, "Well, Mr. and Mrs. Consumer, we have taken out the carbohydrate. By the way, we've greatly increased the fat content." I think you'd rather say, "We've taken out the carbohydrate, and by the way we've greatly increased the protein content." ...

Protein these days has a good image. That may not be the case some time in the future, but it certainly is now.

What would be an example of where you'd find proteins?

Probably the purest and best quality, the gold standard in protein is actually egg white. Egg white is virtually all protein and very high quality. It's the standard against which other proteins are measured. Any kind of flesh food -- that is animal meats, fish meats, shellfish, marine, fowl -- those are all very high-protein sources. In the plant world, protein is typically more dilute. It's more diluted particularly with carbohydrate, and much lower in protein. ...

If you've got the challenge to make a low-carb, low-fat snack food, how do you do it?

Well, again, if you're going to make a low-carbohydrate, low-fat snack food, then you're going to have to have a snack food that's high only in water -- it's difficult to add water because that makes things lose their crunch -- or high in protein. So you must find a protein, and you must find a process to make that snack food that will not destroy that protein or make it inedible. ...

Naively, you think that food is food, and you can't take all the fat and carbs and stick in something else, and get something that tastes the same.

Each food product has a number of specific attributes to it that really, if you're going to replace one food with another food, you must meet [or] at least come close to all those attributes, the most important one in my view being texture. So if you're going to take out the carbohydrate from a snack food and replace that carbohydrate with protein, you must find a way to do that so you produce the same kinds of textures that people find desirable in snack foods.

Texture is really more important than anything else?

Texture typically, in a technical sense, is the most difficult thing to duplicate in a product. It is the most important attribute, what we call "sensory attribute," to a food product. We often don't think about texture, but it is texture that we like.

Let me give you an example. I can take a very low-fat vanilla ice cream and I can take a very high-fat, high-end ice cream. Both of them have sweetness, both of them have vanilla, and I can give them to people and ask them which one they prefer. They will prefer the high-fat one. Why? Because they like the texture of that high-fat ice cream. Texture is a key attribute of any food product. ...

Why [is food] more than just nourishment?

Very often, nutritionists and food scientists think of foods as simply a delivery vehicle for nutrients, but as consumers, we think of foods much, much more broadly. They are very important psychological vehicles for us. People eat when they're depressed. They eat when they're happy. They eat socially. They have religious connections. Almost all religions have some kind of food connected to them, or food laws connected to them. They are fun. Many foods are simply of no value beyond fun, really. They are habit. They are joy. They are unhappiness. Foods are very ingrained in a whole variety of social and psychological aspects, for societies that have the luxury of having such choices.

What has led to our current obesity epidemic?

There've been a variety of factors, and I don't think it's any one simple factor that you can point at, but we certainly have the cheapest food in the world. No one can deny that. That's a fact. We have the greatest bounty and range of foods. There are something like 10,000 new foods introduced into the U.S. every year. Most of those don't make it very far, but they're at least available. So we have a tremendous range of foods. They're cheap.

We understand how to change foods to make them desirable for people, how to take away some of the undesirable aspects of foods. Things like convenience. We live in a society where people want high quality food, but "By the way, I want them in the next 30 seconds," kind of thing. We understand how to do some convenience factors.

We understand how to make them available year round. So in other words, all of these things make food available, and we seem to clearly overuse those foods. The availability and the quality of them make us want them more, and we overuse them. We simply take in too much. ...

How much do Americans eat?

Americans eat about 138 percent, according to the World Health Organization, of the minimum calories that they need. So we clearly over-consume. There's no question about that. That's a fact.

How many pounds of food are we talking about?

An average U.S. resident consumes approximately 1,600 pounds of food per year. That number has been inching up very slowly. Clearly, that amount of food, by itself, is not the sole factor in our obesity problem. Probably what makes up that 1,600 pounds is more important.

What are the food companies competing for?

Every food company is competing for a share of the stomach. In other words, people can only eat so much food. They're only going to consume about that 1,600 pounds. If I am a food company, I must convince that consumer to stop eating some other company's foods and start eating my foods, so they're really competing for what they call the "share of stomach."

Aren't they to blame for producing all these products? How many products are in a grocery store?

A large grocery store will have more than 40,000, maybe as many as 50,000 what the industry calls stock-keeping units, different numbers. So those are all different products, to some degree. Is that a fault of the industry? I don't know. Do we make too many cars? Maybe there're too many choices in cars. Maybe there are too many choices in television programs as well. I don't know. That's usually not the way we play the game. We usually don't play the game by limiting people's choices, whether they're good or bad for them. We play the game by teaching people to make wiser and more limited choices.

Is the argument that they've made more bad food available than good [food] a good argument?

The food industry has produced some horrendously bad foods and some strikingly good foods. The consumer votes with their dollars each time they go into a restaurant or grocery store. The consumer can buy in any grocery store in the United States an extremely healthful diet, in my view. They can also go into the same grocery store and buy a horrendously bad diet, as well.

The food industry is in the position of producing foods that meet consumer demands, whatever those demands are. The industry may not always understand those demands. They may not meet them because they don't know what they are, but they work very hard to meet whatever the consumer wants, be it good or bad. ...

Some say obesity is the biggest public health crisis since smoking. What should we do about it?

There is no question that obesity is a major public health issue. Maybe, behind smoking, the major health issue, and as smoking declines in the U.S. population, the importance of this as a health issue will increase. No question, no disagreement about that.

The disagreements become what to do about it and who's at fault here. And it's easy to point a lot of fingers at different groups and different people, at different industries, and government and nutritionists, and even at food scientists for developing all these foods. But I'm always reminded of Pogo, who I think looked for the enemy and he found out "the enemy are us." And I think that if we want a healthier lifestyle, that we really have to learn how to use foods more rationally and better, and understand what's good for us and what's not good for us. ...

Can the food industry survive if people decide to eat less food?

A very interesting question. … For the food industry, you could make the argument in my view that it would be a benefit for them. They make their money on volume, true. But their food is so cheap that for a healthy lifestyle, I think people, on a per pound basis, would pay more for healthier food. I think that's borne out by lettuce. When a head of lettuce gets to be a dollar, a dollar and a half a pound, there's consumer hysteria. Yet we each go into the grocery store these days and buy a pre-made packaged salad that's more convenient for us. We may pay $8, $9, $10 a pound for that kind of lettuce. So I think that if we provide consumers with a benefit -- better health -- I think we can expect a better return on that. …

How cheap is food, relative to what we earn?

According to the USDA data, I believe that this year food will be about 10.3 or 10.4 percent of the average income, disposable income, in the U.S. If you have above average disposable income, it will be even lower. If you are quite wealthy in the U.S., even though you eat very high quality and expensive food, it may only be 1 or 2 percent of your income. On the other hand, unfortunately, if you're quite poor, you have to spend a bigger proportion of your income for food. But on the average, it's about 10.4 percent.

That makes the U.S. have the cheapest food in the world. The second cheapest food in the world happens to be our neighbors to the north in Canada, followed by the rest of the developed world. If you march on down that list, the developing world can spend as much as 30 to 50 percent of their income on food. ...

[What's the] nutritional history, the swings back and forth, from the standpoint of food scientis[?

The food scientist looks at food very basically made out of these four components, takes food apart and recombines it in a way that we believe people want. If people want healthier foods, we are in a position to make those foods much healthier for them. The problem is that what is exactly a healthy diet seems to change over time quite a bit. We go from times of "low fat is good," now to "high fat is good." Time was that carbohydrates used to be blamed for obesity in the 1970s. All of a sudden now carbohydrates are again blamed for obesity. In between, they were considered good things to eat.

In other words, the target is constantly moving, and so we don't know exactly where to shoot at that target. Our goal then is to understand foods in a basic sense, and be able to produce foods, whatever the best current science says we should do. ...

Aren't you just amplifying theories which could turn out to be wrong?

Certainly the danger is there, and I think that has happened. True that we take what we think is the best advice today, [and it] may turn out in the future we found out it is not the best advice. That's why, when asked for advice, I always say, "A little bit of everything and a lot of nothing," because under that kind of dietary scenario, where you eat a small amount of a wide variety of foods, but not a lot of any food, including carrots or high-fat cookies at either end of the scale, if you eat a little bit across the whole food [range], you're much less [at] risk, and you're certainly staying away from the faddishness of foods and nutrition.

I've heard dire predictions about obesity. Do you see us solving this problem? How would we deal with this love-hate relationship with food?

In my view, Americans are very adaptable and responsive people. I think that you could have made the same argument about smoking in the 1960s: Americans are never going to decrease their smoking. They're never going to be banning cigarettes from restaurants and stuff. We've seen a lot of progress in that.

I think over time we will learn to use foods better as well. As the public begins to demand better foods, the industry -- those industries that can survive -- will provide those better foods. If they don't, they won't survive. Only companies who can meet consumer demand survive in the very, very competitive and difficult marketplace, so I'm optimistic. I think that the controversy, I think that the public debate, I think that even the fringes of this debate are useful because they focus our attention on what is clearly a serious issue, but an issue that I think is quite solvable. ...

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posted april 8, 2004

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