Dr. Sanjay Gupta
00:00:00
‘Hey everyone, it’s Sanjay here. On the last season of the podcast, we talked all about weight and health. And of course that meant talking a lot about food, calories, ingredients, even the times of day that we should eat. Now, the science is obviously pretty clear that eating fruits and vegetables, so-called whole foods, can lead to better health. But here’s a question we also had: just how bad are the food items that are on the other end of the spectrum? My colleague Meg Tirrell wanted to take a deep dive into something you’ve probably heard a lot about recently: ultra processed foods. There is a lot to learn there, some fascinating stuff, and some of it is probably going to change the way you shop.
I’m at my local supermarket picking up the typical things my family eats. Cereal. Milk. Eggs. Crackers. Goldfish. You may have guessed I have little kids. And like most parents, I worry about what they eat. Especially now when it feels like there’s headline after headline about a lot of the items in my shopping cart. Ultra processed foods.
Warning tonight about a silent killer that’s probably in your kitchen cabinets right now.
That’s right, researchers say ultra processed foods, you know, the ones with a laundry list full of additives are the culprit.
Kids in the U.S. are now getting two thirds of their calories from ultra processed foods.
Ultra processed foods. One of my favorites may be as addictive as smoking.
Ultra processed foods contain additives like flavor enhancers, colors, thickeners, gels basically ingredients you wouldn’t usually buy to cook with. And recent studies have linked ultra processed foods to heart disease, anxiety, depression, even cancer. And that’s all obviously really scary stuff. In fact, research finds ultra processed foods make up more than half of the typical American diet. I’m a health reporter and have been for 15 years, and even I feel overwhelmed by some of the things I read about the stuff we’re eating. I really wanted to make sense of it all and I knew I wasn’t alone. So today we’re going to talk with experts and dig through the best available evidence to understand how much of a risk these foods really pose to our health. Do we have to avoid them all? And what’s a realistic way to approach how we eat? I’m Meg Tirrell, CNN medical correspondent, and this is Chasing Life’s Spotlight: Ultraprocessed foods.
So there’s junk food and junk food.
The first person I wanted to talk to as we set out on this mission was Marion Nestle.
I’m professor of nutrition, food studies and public health at New York University emeritus. I retired in 2017.
The professor says she retired after more than four decade career in which she became the voice on food policy, but she still seems very busy. She’s the author of a dozen books on food and food politics, which is also the name of her daily blog. And after speaking with me, Professor Nestle was giving a lecture for an animal studies course about fish.
Then he wants me to talk about how you choose fish. Not simple.
Not simple is how a lot of us feel about most of our food choices right now, especially when you throw in a concept like ultra processed foods. But Professor Nestle says it wasn’t always this way.
Could you go back and talk to us about when these kinds of foods started proliferating, and what’s driving that?
Well, profit is driving it. That’s easy.
There are two key periods in history, she says, that led to this dramatic change in our food supply. The first was World War II.
During the Second World War, there were a lot of industrial processes that were developed in order to produce food for wartime use. And also transportation system that improved enormously during the Second World War. Highways and rail and planes and all of those things that made it possible to move foods from one part of the country to the other. And that was a big stimulus to the food industry to start producing packaged foods that could then be moved from one part of the country to the other.
The next important shifts came in the 70s and 80s. Professor Nestle told us that in the 70s, there was a major change in subsidies for farmers. Instead of paying them to keep fields fallow and avoid overproduction. The message from the government was pretty much get big or get out.
And then in the early 1980s, there was an enormous push to develop more of these things, because under the Reagan administration, there was a lot of deregulation, there was deregulation of marketing, deregulation of lots of controls over the food supply. Food, because of what had happened in the 1970s, became much more produced. So the number of calories available in the food supply per capita went from 3200 in 1980 to 4000 in the year 2000. So all of a sudden, there was an enormous amount of food available that had to be sold.
There was also a change in how Wall Street looked at companies to invest in.
Wall Street changed in the early 1980s from approving slow, long term returns on investment blue chip stocks like IBM to an insistence that there be immediate higher returns on investment. And as a result, food companies had to not only sell foods in an environment in which there was probably twice as much food available as the population needed, but they had to grow their profits every 90 days to report it to Wall Street. So the food industry looked for ways to sell more food, and they made bigger portions. I think a sufficient explanation for the rise in obesity during that period. Larger portions have more calories. But they also started introducing lots more processed foods, ultra processed foods. They did a lot of work on trying to figure out what flavor and texture and color combinations would be most attractive to people, and started producing foods that would make them lots of money because they had to grow their profits.
So that brings us to today, where, according to a 2022 study, ultra processed foods make up about 57% of the calories consumed by U.S. adults. But what exactly are they? Because, as Professor Nestle said.
There’s junk food and junk food.
‘In 2009, researchers at the University of Sao Paulo in Brazil proposed a new way of classifying food not based on what kind of food it is – meat, grains, vegetables, etc., but based on how processed it is. They wanted to better understand patterns in eating behavior and how what we’re eating affects our health. The system, called NOVA, separates foods into four groups based on their level of processing from group one natural and minimally processed foods like rice, apples, or eggs all the way to Group Four: ultra processed foods that come from a series of industrial processes. In other words, ultra processed foods are ones that have been altered the most before they get to you. And Professor Nestle doesn’t even call these things foods in some cases. She calls them food products. We broke this down by comparing two bags of chips.
So if we look at some of these snacks that I stole from the CNN kitchen, I’m holding up a bag of, Fritos, which are called the original corn chips. And the ingredients listed. This kind of surprised me. Corn, vegetable oil.
Yeah, they’re too salty. That’s my objection to them. But those are not ultra processed.
They’re not. So then. Okay, I’ve got these…
You could reproduce that recipe in your home kitchen. My operating definition for ultra processed is you can’t make it in your home kitchen because you don’t have the machinery and you don’t have the ingredients. In the case of Fritos, you have the ingredients. And you could take corn, mash it up, fry it and turn something in and turn it into something like Fritos. But it’s when you get into the complicated ingredient lists that you get into the ultra processed territory. Now, it may be that you can’t stop eating Fritos. Yeah, but Fritos. But Fritos have a sort of simple flavor. And I think most people start eating them and they’ve had enough. Those little bags of them are enough. Some of these other things are have more combined flavors that are so attractive and so delicious that people just can’t stop.
But then I’ve got these Baked Lay’s. Let’s look at the ingredients. Dried potatoes, corn starch, corn oil, sugar, sea salt, soy lecithin, dextrose and annatto extracts.
It is! Okay. What on there makes it ultraprocessed?
The ingredients that you can’t, you can’t go to a supermarket and buy. I would rather have Fritos. I just wish they weren’t so salty.
And she says classifying foods this way opened up a whole new frontier of research.
Once you had a definition that specified a specific category of foods defined in a specific way, that you could start doing research and say, what about all these studies looking at what people eat and how sick they get? Let’s look at what they were eating. Were they eating a lot of ultra processed foods? And so those studies, observational meaning that they were just looking at what people were reporting eating and their health outcomes. But they started coming out and they started coming out more and more and more. And now there have been more than 1500 observational studies, all of them demonstrating a consistent finding, which is that eating ultra processed foods is linked to obesity, type two diabetes, heart disease, certain cancers, bad outcome from Covid 19, overall mortality. Any bad health problem you can think of, that’s related to diet is related specifically to ultra processed foods.
But a link isn’t the same thing as saying ultra processed foods are the reason for those health problems. I guess that’s sort of the question is when do you say linked and when can you say ultra processed foods cause health problems?
Well, you can do that when you have a controlled clinical trial. And guess what? We have one.
But so far just one. And that’s because as we’re about to hear, these kinds of controlled clinical trials are really tricky to do when it comes to food. Coming up after the break. We talk with the researcher who ran that study about what it found and how our bodies respond when we eat ultra processed foods.
What they didn’t know is that we were measuring their leftovers.
They lived with us 24 hours a day, seven days a week for an entire month.
I’m a senior investigator here at the National Institute of Diabetes, Digestive and Kidney Disease, which is one of the National Institutes of Health just outside Washington, DC.
In 2019, his team ran a controlled clinical trial on ultra processed foods. It was the first of its kind, and so far it’s still the only one that’s been published. Which is kind of crazy when you think about it, considering how much of our food is ultra processed. But first, it’s worth telling you that Kevin has spent a lot of time studying how our bodies respond to what we put in them. In fact, you may be familiar with some of his work about what happened to participants on a popular reality TV show.
Biggest Loser Clip
00:12:11
Millions of overweight Americans have tried out for the chance to leave their friends and families behind and change their lives. I would never even think about worst nightmares that that would be this big.
Biggest Loser Clip
00:12:23
Your current weight is….
Kevin and his team followed participants in the reality show The Biggest Loser for several years, and he says what he learned helped him understand more about weight and metabolism, and led to more questions about what drives weight gain. Even though, as he says, the show wasn’t exactly a typical experience.
We measured them over the seven months that they participated in this crazy, you know, lifestyle intervention. I guess it’s a kind way to say it, but it’s it was pretty fat shaming kind of train wreck of a television show, to be honest. But they were doing it anyway, so we were really interested to see what was happening metabolically inside their bodies.
His research found that in the six years after the show, maintaining such massive weight loss was incredibly difficult for people despite huge amounts of willpower.
They maintained on average, about 13% weight loss after six years, which is a pretty decent amount of weight loss. But the way it was sort of covered in the press, given how dramatic the weight loss was initially it looked like they failed, but in fact they could never have kept up. I mean, imagine three hours a day of exercise, seven days a week. They are probably doing something close to an hour a day, when they when they kind of were six years later. Yeah.
Which is still like a huge commitment and somebody who can’t find an hour a week.
Yeah. It’s it’s pretty clear that these people did not lack willpower. Right. They had willpower in abundance. And I think that a lot of people with obesity are stigmatized with this idea that, you know, somehow they just lack the willpower to kind of change their lifestyle. And what I think a lot of people don’t realize is that that’s clearly not the case. You know, we have this surge in obesity rates that kind of started to take off in the 1980s. There was not a, you know, population wide lack of willpower that was associated with that. Some people were more susceptible to that increase in body weight and which is probably caused by the environment, but it’s interacting with our genetics. So in any given environment, people with obesity have a greater susceptibility because of their genes. So we are really interested now in trying to understand what it is about our food environment that affects how much we choose to eat and how does that affect our weight.
Okay, so after his studies showed that even people with willpower in abundance have trouble keeping weight off, Kevin now wanted to understand what was contributing to society’s weight gain. Initially, he says, he looked at the ratio of nutrients in what people eat. So carbs to fats, to protein and so on. Until he gave a lecture at a medical conference several years ago.
After the talk, a couple of folks came up to me and said, you know, you guys are still talking about nutrients, but that’s not what’s important, right? There’s what’s important is how processed the nature and extent of the processing of foods and the purpose of processing of foods. That’s what’s important. That’s nutrient stuff. That’s all sort of, you know, 20th century, nutrition science get with the program.
There’d already been a number of studies showing a link between ultra processed foods and obesity, type two diabetes and other health conditions. But Kevin says there wasn’t a clear explanation as to why. And the studies so far were all observational, meaning they couldn’t rule out other influences or causes.
‘These folks are self-selecting their diets. There might be something else different about these people, not just the diets that is driving the effects for the increased risk. And so that was the state of the science at the time. And we kind of decided, well, could we actually design a randomized controlled trial that’s clearly not going to last for, you know, decades or something like that, like these cohort studies are, but could we kind of do a really controlled study where we change people’s food environment in a highly controlled setting and just observed how they responded when they didn’t know what the purpose of the study was? They didn’t know, you know, exactly what we were measuring. And, also we were measuring a lot of different things. And how would they behave when we changed their food environment in terms of how much ultra processed foods were available to them, but then matched them for various nutrients of concern like the salt, the sugar, the fat, the fiber, the carbs, the overall energy density, glycemic load, etc. etc..
I think this is so interesting, and I think when you get into the details of how you did this experiment, it really explains why we don’t have a lot of research like this, because this is really labor intensive, right? I mean, you basically invited these folks, 20 people to live at the NIH Clinical Center for a month, right?
That’s right. And and it’s really slow going as well. Right? Because we can’t do it all at once, right? We have so many beds. It’s basically a hospital. The NIH Clinical Center is a big research hospital. And we have one ward on that hospital called the metabolic ward, where we have really tight controls over, you know, the food that goes in and out. And and so we know that people can’t cheat on their diets, but it’s a very artificial environment. But with your right, we have complete control. The only food that they’re exposed to is the food that we provide them in the study.
So 20 people each spent a month living at the NIH Clinical Center. For two weeks, each was given a very specific diet. One contained no ultra processed foods, while the other had 80% of its calories from them. The meals were matched for how many calories they contained, macronutrients which are carbs, fat, and protein, as well as for fiber, sugars, and sodium. After two weeks, the participants were switched to the other diet, and they were given loose fitting clothes to wear, so it wouldn’t be as apparent to them if their bodies were changing. They weren’t aware of their weight, and everyone exercised for 60 minutes a day on a recumbent bike.
We basically just asked people, you know, just eat as much or a little of the food that you’d like. You shouldn’t be trying to change their weight, shouldn’t be trying to gain weight or lose weight. Just eat to the same level of appetite as you normally would. And what they didn’t know is that we were measuring their leftovers.
Creepy. But it was for science. Now, we asked Kevin how they managed to convince 20 people to give up a month of their lives for a study like this. And as it turns out, there was a lot of interest.
So it’s actually more like we try to convince people not to do it. The positives are you’re going to get free food. You’ve got time to kind of work on your pet project. So we get a lot of people who would want to finish manuscripts or studying for exams, or want to write a business plan. They don’t want to have to worry about cooking. They don’t want to have to deal with their significant other or their kid bugging them every 30s. So some people feel like it’s almost like a little bit of a kind of a productivity boost.
The participants could eat as much as they wanted at mealtimes, and they also had access to snacks if they were hungry between meals. And it was the snacks on the ultra processed diet that really surprised me, and not in a good way. This really freaked me out as a parent. I think I serve a lot of these foods to my children fairly readily due to obesity. Okay, that makes me feel a lot better.
Goldfish crackers, right?
Exactly. The snacks here are Goldfish crackers. Baked Lay’s. Which like, Baked, are the healthy ones, right? These cheese and peanut butter crackers. I mean, those are like an odd shade of orange. I feel like that is pretty obvious. Salted peanuts. And, is this applesauce? That seems like a fairly healthy thing, but those are ultra processed.
They are. They are ultra processed.
So after all, the participants got through two weeks on one diet and then two weeks on the other. Kevin and his team assessed the results. They were specifically looking to see whether there was any difference in how many calories people eat on each diet. And he says he assumed they wouldn’t see much of a difference, because the conventional wisdom was that ultra processed foods led to weight gain because they’re high in salt, sugar and fat and low in fiber. And in the study, they matched the two diets in terms of nutrients.
I was kind of entrenched in the sort of nutrient focused world. I thought it was all about nutrients. And it turned out that I was dead wrong.
In fact, there was a significant difference. People on the ultra processed diet ate about 500 calories more per day than those on the minimally processed diet, which affected their weight almost immediately.
‘They sort of spontaneously were gaining weight, gaining body fat. And then when they were on the minimally processed diet, they were just losing weight and losing body fat, eating the same self-reported levels of appetite. So they weren’t any more hungry. They weren’t any more full. They didn’t have any differences in satisfaction. They didn’t feel like they could eat more or less of the diets than they actually ate. And so they were doing as they were told. It just turned out that when they were exposed to a food environment that was composed primarily of ultra processed foods. Something about that food environment caused people to overconsume calories by a huge amount. And when you expose them to a diet that had 0% of calories from ultra processed foods, which is very different than our usual food environment, they basically spontaneously lost weight and lost body fat.
The average weight gain over two weeks on the ultra processed diet was about 2 pounds, whereas people on the minimally processed diet lost an average of 2 pounds. And researchers saw changes in health markers in the blood to.
A marker that’s related to inflammation was much lower when they were on the minimally processed diet, and it was basically relatively unchanged from baseline at sort of chronic levels of mild inflammation in both the ultra processed diet and at baseline, which isn’t too surprising because, like I mentioned before, about 50% of the calories that people consume are on the outside when they’re not, as part of our studies are probably ultra processed. So the real change for them was the minimally processed diet here.
They also saw early signs of changes in hormones that could have played a role in what they found. People eating the minimally processed diet, for example, had higher levels of hormones that suppress appetite. So what explains these differences? Well, they don’t have a complete answer to that yet. But there was one thing between the diets that they couldn’t match completely.
One of the things that was different between the two diets was when you remove the beverages from both diets, the number of calories per gram of the foods on the plate were actually higher in the ultra processed diet, mainly because ultra processed foods tend to be drier, so water doesn’t contain any calories that your body can use. And when you actually engage in this sort of industrial manufacturing process, one of the things that manufacturers are trying to do is to extract as much water as possible, because it it it improves the stability of the product. So they don’t kind of rot. And so basically what you end up doing is concentrating the calories and removing all that water that would normally dilute them. And so the energy density of these food items was actually quite a bit higher. And so that’s another hint that that might be a mechanism by which people could eat more calories so… Think about it like this. Every bite of food that you eat contains more calories when it’s ultra processed compared to a minimally processed food.
And not only are you getting more calories per bite with ultra processed foods. The study also found something that could have a big influence on how we decide what we’re eating. When you buy ultra processed foods, you’re likely saving money.
To actually create the minimally processed menu. It was about 40% more expensive than the ultra processed menu, and that doesn’t even account for the time that it takes to make the foods. So all those factors probably play a huge role in why we choose to eat the foods that we choose to eat in the real world.
So the study found that people eating a diet made up mostly of ultra processed foods ended up eating an average of 500 calories more per day, and that resulted in weight gain of about 2 pounds over the course of two weeks. And people eating a minimally processed diet actually lost about that much weight. Professor Nestle says this finding was really important.
If you’re not familiar with nutrition research, you have no idea what an important finding this is. 500 calories is huge. Most dietary comparisons have happy investigators if they can show 50 calories different. This was 500.
And she calls it one of the most important nutrition studies done since the discovery of vitamins.
I think the observation is sufficient to say, if you’re worried about your weight, stop eating ultra processed foods, or make sure that if you eat ultra processed foods, you don’t eat very much of them.
Okay. Just zooming out for a second. What if you’re not worried about your weight or you enjoy some ultra processed foods? Are some worse than others? And do I have to hide the goldfish from my kids? On that point, Kevin had some reassuring news. Remember how the snacks in the ultra processed diet in the study included my beloved goldfish?
You’ll be happy to know that they didn’t eat any more calories in the snacks between the two groups, so the snacks were neutral in terms of how many calories they ate. Which goes to show that not all ultra processed foods necessarily drive this effect, right? And that’s one of the things that we’re really interested in now is that trying to figure out what the mechanisms were.
And that’s the next leg of Kevin’s research at the NIH.
If we knew the mechanisms, then we would know exactly what the problem was and how to sub categorize the harmful ultra processed foods from the neutral, ultra processed foods from the healthy, ultra processed foods.
Are you designing a study around that?
We actually have people enrolled now at the Clinical Center to vary and reformulate our ultra processed diets, to try to see if we can still have diets that are 80% of calories from ultra processed foods, but don’t drive people to overconsume. So that’s a study that we have ongoing right now, is testing reformulated, ultra processed diets. And with the hopes, if we’ve done it correctly, that we can still have a high amount of ultra processed foods that are still tasty and still convenient, but don’t cause people to overeat.
‘And Kevin says he expects the results from that study early next year. Now, we also reached out to the food companies that make the products mentioned in this episode. Campbell’s, which makes Goldfish, told us, quote, we make delicious food with quality ingredients. The company said there’s no agreed upon scientific consensus on the definition of ultra processed, and pointed to Kevin’s findings on snacks, quote, as a good example of why it should not be labeled subjectively. PepsiCo, the parent company of Frito-Lay, which makes Fritos and Baked Lay’s, told us they follow the science closely and that they’re committed to improving the, quote, core nutritional profile of their products, including using more diverse ingredients. And they noted they’d already reduced sodium and saturated fat across the products they sell. Finally, I asked Kevin the question I really wanted to ask all along. After doing this work, did you change the way you eat?
You know, not so much. I always sort of ate a relatively healthy diet, and yeah, it probably didn’t have a huge amount of ultra processed foods in it. I mean, it was still probably something like 30 or 40%, which is kind of not super low, but it’s not terribly high either. I mean, my kids, like you mentioned earlier, I have a nine year old and a six year old, and it’s really tough to get them to eat a minimally processed diet. And at the end of the day, when you’re exhausted and you just don’t want to have a fight with your kids about what they’re going to eat. You know, my balance is, yeah, they’ll end up eating maybe some chicken nuggets, but they’ll also have some green beans and some carrots or something like that, or some chickpeas, things that are minimally processed. But yeah, there’ll be an ultra processed component probably of their dinner plate, but I try to balance it off.
Hearing that made me feel a lot better about the choices I’ve been making since I started researching this episode. I have actually changed the way I eat a little bit. I do read the labels on foods more than I did before, and maybe I won’t pick something up that I used to think might have been healthy. So to every other stressed parent out there and really anybody else who’s in the grocery store aisles feeling really bad about the food choices you might be making. I think what I’ve taken away from Kevin’s study is that it’s not as black and white as we feel like it is. We don’t have to beat ourselves up. Kevin Hall’s research tells us that, yes, there are reasons to avoid eating too much ultra processed food, but even he hasn’t cut it out completely. And hopefully we’ll get more data soon on how to make even better, more informed choices. And it feels really important to take a step back and realize that the fact that these foods can be so much less expensive and so much more convenient, means it can be a privilege to be able to avoid them. We talked with Professor Nestle about this and she said fixes. For that kind of problem really need to come at a broader societal level. Things like nudging food companies to make healthier versions of these products, or even teaching cooking in schools.
Bring back home economics.
Perhaps it’s not surprising that, like any diet advice, balance here is key because after all, even a nutrition expert like Marion Nestle likes a bag of Fritos once in a while. Chasing life is a production of CNN audio. Our podcast is produced by Eryn Mathewson, Jennifer Lai, and Grace Walker. Our senior producer and showrunner is Felicia Patinkin. Andrea Kane is our medical writer, and Dan Dzula is our technical director. And the executive producer of CNN Audio is Steve Lickteig with support from Jamus Andest, John Dianora, Haley Thomas, Alex Manasseri, Robert Mathers, Lainey Steinhardt, Nichole Pesaru, and Lisa Namerow. Special thanks to Ben Tinker, Amanda Sealy, and Nadia Kounang of CNN health, Sandy Lamotte and Katie Hinman.
