‘To me it’s junk food’

Over the past several decades, the American diet has undergone extraordinary changes. Increasingly, Americans are relying on processed food products as key parts of their everyday meals. In fact, in January of this year, the Journal of Nutrition found that a very specific type of processed food — ultraprocessed foods — now make up more than half of adults’ diets in the United States, and that percentage has been steadily increasing over the past two decades.

Despite ultraprocessed foods’ ubiquity in our food supply, scientists are just starting to scratch the surface in understanding how these food products influence our health. Interest in this connection has also skyrocketed, with numerous studies linking myriad diseases and conditions — from Type 2 diabetes to heart disease, cancer, and irritable bowel syndrome, to name a few — to a diet high in ultraprocessed foods. Now, these products have reached the political discourse. Newly-elected United States Secretary of Health and Human Services Robert F. Kennedy Jr. has targeted ultraprocessed foods as a key part of his plan to fulfill President Trump’s ongoing campaign to “Make America Healthy Again.”

On Feb. 11, just before RFK Jr. was confirmed as health secretary, I sat down with Marion Nestle, a public health advocate and professor emeritus of nutrition, food studies, and public health at New York University, to discuss the current state of ultraprocessed foods: how we got here, what we know about what these food products do to our health, how we know that, and what she thinks we need to do to move forward. 

This interview has been condensed and edited for clarity.

Claire Maldarelli: How did you become interested in studying food and food policy? 

Marion Nestle: I was teaching cell and molecular biology at Brandeis University, and I got handed a nutrition class to teach. It was like falling in love, and I’ve never looked back. It was so much easier to teach because students were just passionately interested in the topic and they really cared about what they were eating. So we had a really good time. 

CM: What was food and nutrition research like then compared to now? Was it as popular as it is now? 

MN: Then, in 1975, everybody thought there had been this sudden interest in nutrition. Linus Pauling had just published [his studies on] vitamin C and the common cold. Frances Moore Lappé had just finished publishing Diet for a Small Planet, which was enormously influential. Michael Jacobson had just started the Center for Science in the Public Interest, which published a book called Food for People, Not for Profit that I used as a textbook in that first class. It was right there from the beginning. So the interest has grown, yes, and there’s much more about it in the popular press, but there was a lot then, too. 

CM: Over the past several years, ultraprocessed foods have headlined much of the nutrition and health news. Yet the term itself still feels somewhat ambiguous and confusing to many Americans. Briefly, what exactly is an ultraprocessed food?

MN: To me, it’s junk food. It’s just a very defined category of junk food: one that you can’t make in a home kitchen, designed to be profitable and addictive, and it usually contains a lot of additives for color, flavor, and texture. Sometimes, it contains a lot of sugar and salt and saturated fat, but not always.

Where the ambiguous arguments lie is at the margins. For example, there are some ultraprocessed foods that aren’t as junky as others. Whole wheat sliced bread is an example. Another is commercially produced yogurt. But beyond those examples — and there are very, very few of them — there’s no [argument]. 

CM: When did the term ultraprocessed come to research and public interest?

MN: It was invented in 2009 by Carlos Monteiro who, at the time, was a professor of public health at the University of São Paulo in Brazil. (He’s now retired.) He and his colleagues developed the term to try to understand what was happening in Brazil with the introduction of these new products that were changing the way Brazilians ate. [They were] going from a traditional Brazilian diet that was really pretty healthy and based on real foods to one that was based on processed foods, and they could see that the nutrition transition was occurring. People in Brazil were gaining weight. 

But the thing that’s so important about this new term is that once you have a definition of a category of food, you can go back and look at loads of epidemiological studies and look at what people were eating and how much of the foods they were eating was ultraprocessed. That’s how researchers were able to do all these correlations studies. 

CM: What did the correlation studies find? 

MN: The correlation studies have a level of consistency that’s kind of breathtaking. They all show the same thing: That the more ultraprocessed foods people ate, the worse health outcomes they had. It’s directly linear, and it’s phenomenally consistent. 

Now those are observational studies so they show correlation, not causation. But there are now at least three extremely well-controlled clinical trials that show that ultraprocessed foods induce people to eat more calories than they otherwise would — a lot more calories — enough to account for weight gain and obesity in the population. These studies need to be taken very seriously. When I’m at my most hyperbolic, I say they’re the most important studies done in nutrients and vitamins. 

CM: What did these studies entail? And what is their significance? 

MN: The subjects in those studies were in locked metabolic wards. That means they couldn’t lie or cheat about what they were eating. They were fed two different diets. One was a diet made up entirely of unprocessed foods. The other was one made up of entirely processed foods. But they were matched in protein, fat, carbohydrate, vitamins, minerals, fiber, and, importantly, palatability. The study subjects couldn’t tell the difference between the two different kinds of diets they were put on.

The studies showed that those on an ultraprocessed food diet ate, on average, 500 more calories per day. I mean, that’s a phenomenal result. An astonishing, absolutely unambiguous result. Now the investigators are trying to figure out what it is about these foods that encourages people to eat so much of them.

CM: Do you think calorie intake is the most important factor when we are talking about ultraprocessed foods? Not the food additives or something else in the food?

MN: I’m a calorie person. I think you can explain a great deal of the rise in chronic disease — certainly obesity — from calories. That’s thermodynamics. You can’t argue with that. Why that happens is what’s being studied. 

But I think we live in a food environment that encourages us to eat foods that are ultraprocessed because they’re the most profitable in the food supply and they were deliberately designed to be irresistibly delicious so you can’t stop eating them and you want more. 

As one of my friends explained it, “When you eat a salad, you know when you’ve had enough salad. Put Oreo cookies or barbecue potato chips in front of me, and I can’t stop.” Everybody has this experience. And that’s what ultraprocessed foods are designed to do, is to get you to keep eating them because the food company’s purpose is to sell food products. 

CM: What else can these studies do that the correlation studies can’t?

MN: The results were so unambiguous that if you were going to issue dietary guidelines, the first thing you would do would be to advise people to cut down on ultraprocessed foods. 

However, the dietary guidelines advisory committee chose not to consider those studies in its recommendations to the Departments of Health and Human Services and United States Department of Agriculture because the studies were too short. They stated that if the studies had lasted longer, they would have shown a much smaller difference in calorie intake.

Well, we don’t know that, do we? I mean, it’s a good guess, but we don’t know that, but the idea that they would ignore these studies to me was like ignoring the elephant in the room. There’s an elephant in the room, but let’s not pay any attention to it. I was flabbergasted.

CM: Why were these studies so short? 

MN: They cost a bloody fortune. You have to get volunteers who are willing to be locked up for a month. While they’re there to be fed and to be measured endlessly, everything they eat, drink and excrete is measured. 

CM: Is there a way to make ultraprocessed foods healthy? 

MN: That’s a very complicated question. I think the food industry is in trouble right now. There are four big threats to it. One is public interest in [the negative effects of] ultraprocessed foods. Second is the GLP-1 drugs, in which one of their side effects is they make people not want to eat ultraprocessed foods. Third is inflation. And fourth is Robert F. Kennedy Jr., who wants to get ultraprocessed foods out of the food supply. The food industry sees this as the writing on the wall, and these four things coming together.

The purpose of a food company is to sell food, especially if it’s publicly traded. If it’s publicly traded, then it goes by the shareholder value movement, in which the most important goal of a corporation is to make profits for stockholders. Unless we change that and change the rules by which companies are evaluated, that’s not going to shift. So the healthfulness of the product is a non-issue. 

CM: At the time of this interview, RFK Jr. has yet to be confirmed as secretary of the Department of Health and Human Services. But he has stated that “highly chemical intensive processed foods” were the “culprit behind many of the chronic diseases affecting Americans.” And, if confirmed, he has said he would attempt to fix the food supply by targeting how these foods are produced and sold. If RFK Jr. is confirmed, what would you want him to do regarding ultraprocessed foods? 

MN: There are a number of things that you could do to make it more inconvenient and more expensive to buy those foods. For one, he could call for warning labels on all ultraprocessed foods, like they have done in many Latin American countries. He could also raise the prices of ultraprocessed foods. And last, he could put restrictions on marketing. 

That’s never been a Trump agenda, though, so I’m not sure where that’s going to go. And I haven’t seen strong food industry opposition to his candidacy. It may be behind the scenes, but I haven’t seen any public statement. And he’s been in a lot of debates opposing his candidacy from the food industry, which makes me think that the food industry must not think that he’s for real, but I don’t know that. We’ll find out in due course. 

CM: Has anyone been able to stand up to the food industry in the way that RFK Jr. wants to? Is there any precedent for that? 

There’s certainly precedent. They’ve been able to get warning labels on food products in several countries in Latin America. They’re very, very worried about obesity there because they don’t have enough money to pay for treatment of Type 2 diabetes, which is an expensive disease to treat.

In the United States, there’s never been a public health campaign at the national level, a real one, to try to get people to reduce their calorie intake. Part of that is because eating less is really bad for business. The food industry doesn’t like it. The food industry’s job is to sell more food, not less. So, there are these sort of built in contradictions here.

CM: A lot of the blame gets placed on individuals to say “I am just going to avoid ultraprocessed foods.”

MN: Oh, good luck with that. These are powerful forces that are, in every possible way, trying to get you to eat more of their products: by having them displayed, by having them cheap, by advertising them, by having them talked about on social media, by having them seem so normal that to go to a supermarket and not buy sugar sweetened beverages seems like a weird thing to do. 

And you’re not supposed to notice any of this. The way an advertising executive explained it to me was that if the advertising is successful, it slips below the radar of conscious thought. It’s impossible. 

CM: What would be your dream scenario for combatting ultraprocessed foods? 

MN: We would have publicly funded election campaigns and candidates for office would not be able to spend one penny more than what the public allowed. We would overturn Citizens United, the Supreme Court decision that allowed unlimited corporate money in politics. 

That’s my starting place. Then I want an agricultural system that is focused on food for people rather than feed for animals and fuel for automobiles. I want farmers growing fruit and vegetables for people under regenerative, organic, sustainable conditions. 

I want universal school meals, so kids get fed in school. Foods that the kids are eating in school should be healthy. I totally agree with RFK Jr. that ultraprocessed foods should be removed from schools. I want to see a universal basic income so that poor people can have enough money to buy healthy foods. Dietary guidelines should be straightforward and honest and should talk about the need to avoid eating junk food and ultraprocessed foods.

That’s my shopping list.

CM: What about the role of food companies in advertising?

MN: I like restrictions on advertising. Especially restrictions on advertising to children. I think advertising junk food to children is unconscionable. I once went to a meeting at the White House when the Obamas were in it. And it was a meeting run by Michelle Obama about marketing food to kids. After the speeches, everybody broke up into smaller groups to discuss what could be done. And in my smaller group, there was an executive from a very large food company who said, “You know, I wish we didn’t have to market to kids. … I really don’t think it’s right. I wish we could stop, but our stockholders won’t let us.”

And if you, as an individual, are trying to keep your kid from demanding sugar sweetened cereals, or other kinds of snack foods that are designed for kids, you know, with millions and millions of dollars in advertising and promotion budgets behind them, you’re fighting that on your own. That’s pretty hard for individuals to do. 

CM: Do you think that means individuals should just give up? 

MN: No! Organize! Advocate! If a senator’s or representative’s office is flooded by phone calls and letters asking them to do something or to stop doing something, they’re going to have to pay attention. Yes, it’s a slow process. Yes, it’s cumbersome. Yes, food companies have a lot more money than you do. But there are ways of fighting back and sometimes you succeed. And if you don’t fight back, you certainly won’t get what you want.