RHR: The Hidden Harms of Ultra-Processed Foods

In this episode we discuss:

• What ultra-processed food actually means
• How the NOVA classification system works
• Why “healthy” packaged foods can still be ultra-processed
• What research reveals about UPFs and overeating
• How ultra-processing affects the food matrix and nutrient absorption
• Potential connections between UPFs, gut health, inflammation, and metabolic dysfunction
• What food additives and processing-related compounds do in the body
• How to identify ultra-processed foods by reading ingredient lists
• Simple ways to reduce your intake and eat more real food

Show notes:

• “Consumption of ultra-processed foods and associated sociodemographic factors in the USA between 2007 and 2012: Evidence from a nationally representative cross-sectional study” by Baraldi, L. G., et al.
• “Oxidized proteins in ready-to-eat beef are likely responsible for oxidative stress, dysbiosis and poor gut health in Wistar rats: Underlying biochemical insights” by Caballero, V., et al.
• “Ultra-processed diets cause excess calorie intake and weight gain: An inpatient randomized controlled trial of ad libitum food intake” by Hall, K. D., et al.
• “Ultraprocessed food versus diet quality in relation to cardiometabolic health and all-cause mortality: NHANES 1999–2018” by Hatta-Langedyk, J., et al.
• “Ultra-processed food consumption and risk of cardiovascular events: A systematic review and dose-response meta-analysis” by Qu, Y., et al.
• “The detrimental impact of ultra-processed foods on the human gut microbiome and gut barrier” by Rondinella, D., et al.
• “Trends in consumption of ultraprocessed foods among US youths aged 2-19 years, 1999-2018” by Wang, L., et al.
• “Association between ultra-processed food consumption and mortality among US adults: Prospective cohort study of the National Health and Nutrition Examination Survey, 2003–2018” by Wang, L., et al.
• Learn more about the Adapt Naturals Core Plus Bundle or take our quiz to see which products best suit your needs
• If you’d like to ask a question for Chris to answer in a future episode, submit it here
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Hey everybody, Chris Kresser here. Welcome to another episode of Revolution Health Radio. Today we’re going to talk about something that’s been dominating health headlines this summer: ultra-processed food. If you’ve spent any time reading health news in 2026, you’ve probably seen the term everywhere, from the American Journal of Public Health to CNN to your social media feed. And there’s a good reason for that. The research coming out right now is changing how we think about what makes food harmful.

I’ve been talking about food quality for over 20 years, and I have a pretty simple philosophy– eat real food. Three words, that’s it. When I was seeing patients, I used to tell them, “If it comes in a bag or a box, you probably shouldn’t be eating much of it.” Some people thought that was oversimplified. The usual pushback was something like, “Isn’t it really about the macros? The calories? The specific nutrients?” And for a long time, that was the mainstream position– food is just a vehicle for delivering nutrients, and as long as you hit your targets, it doesn’t matter whether those nutrients come from a chicken breast or a protein bar. But the latest research has confirmed what those of us in functional and integrative medicine have been arguing for decades– it’s not just what’s in processed food that’s a problem, it’s what processing does to the food itself. A major study from Tufts University, published in the American Journal of Public Health in June 2026, analyzed data from almost 50,000 adults over two decades of NHANES surveys. What they found challenges the entire framework that mainstream nutrition has been operating on, and it has big implications for anyone who thinks they’re eating healthy because they buy organic protein bars and almond milk from the health food store.

By the end of this episode, you’ll understand what ultra-processed food is and how to identify it, why the nutrition label doesn’t tell you the whole story, what new research reveals about the specific mechanisms of harm, and what practical steps you can take to reduce your exposure. Let’s dive in.

Okay, let’s talk about what ultra-processed food means. The term comes from a classification system called NOVA, developed by researchers at the University of Sao Paulo. NOVA sorts all food into four groups based on the degree of industrial processing it’s undergone. Group one is unprocessed or minimally processed food– fruits, vegetables, eggs, fresh meat, plain nuts. Group two is processed culinary ingredients– olive oil, butter, salt, sugar. Group three is processed food– canned vegetables, artisan cheese, traditionally cured meats. These three categories are all things your great-grandmother would have recognized. Group four is where it goes off the rails. Ultra-processed foods are industrial formulations made mostly or entirely from substances derived from foods and additives, with little or no intact food in the final product. We’re talking about ingredients like protein isolates, hydrogenated oils, modified starches, emulsifiers, thickeners, flavor enhancers, and colorings. These are substances that require industrial equipment to produce. You couldn’t make them in your home kitchen.

Here’s a shocking statistic– almost 60 percent of the calories Americans consume come from ultra-processed foods. Let me say that again. The majority of the calories the majority of Americans eat are not foods at all. They’re chemicals, additives, isolates, and other Frankenfoods. A 2018 analysis of NHANES data confirmed that figure, and it’s been trending upward since. Among kids and teenagers, it’s even worse. A 2021 study in JAMA found that the estimated percentage of total energy from UPFs, ultra-processed foods, among U.S. youth aged two to 19 increased from 61 to 67 percent between 1999 and 2018. Two-thirds of what our children eat is industrially manufactured food product. And the disparity is stark across racial and socioeconomic lines. Among non-Hispanic Black youth, UPFs climb from 62 to 73 percent of total calories over that same period. That’s not a small dietary quirk. That’s the dominant feature of the American diet, and it’s worsening for the populations that can least afford the health consequences.

This brings us to a really important distinction that most people miss, including a lot of health-conscious people. Processing itself isn’t inherently bad. Cooking is processing. Chopping vegetables is processing. Fermenting cabbage into sauerkraut is processing. These forms of processing often make nutrients more bioavailable and food safer to eat. The problem is specifically industrial ultra-processing, the kind that strips food of its natural structure, removes beneficial compounds, and adds substances that serve the manufacturer, not the consumer.

One of the most common patterns I saw in my years of clinical practice was the health-conscious person who was eating a diet dominated by ultra-processed foods without realizing it. They’d skip eggs and bacon for breakfast because they thought it was unhealthy, and instead ate granola with almond milk, or sweetened yogurt with a protein bar on the side. They’d grab a plant-based meat burger for lunch, thinking they were making a better choice. A “healthy” smoothie from the juice bar for an afternoon snack. Everything was organic. Everything was from the health food store, and almost all of it was NOVA Group Four ultra-processed food. These were smart, motivated people who genuinely cared about their health. They’d done their research. They read labels. They spent more money on food because they believed they were buying quality. And they’d come to me frustrated because they were doing everything right in their minds, but still dealing with digestive issues, fatigue, stubborn weight, and blood sugar problems. When we’d actually audit their diet, the pattern was that they’d been fooled by the health halo. This is one of the biggest misconceptions in nutrition today. Just because something is sold in a health food store, just because it’s labeled organic, just because the marketing says “clean” or “natural,” doesn’t mean it hasn’t been industrially processed.

Protein bars are a perfect example. The protein isolation process alone, which typically involves alkaline extraction and acid precipitation, is impossible without industrial equipment. Add in the emulsifiers, maltodextrin, sugar alcohols, and natural flavors, and you’ve got a food product that bears very little resemblance to any actual food. Plant-based meat alternatives are another one. Beyond Burgers, Impossible Burgers, these are marketed as healthier and more sustainable alternatives to regular meat. But a 2023 analysis of the German food market found that plant-based meat products contain more ultra-processing markers than the actual meat products they’re designed to replace. That shouldn’t be surprising, right? Methylcellulose, soy protein isolate, refined coconut oil, a long list of additives and chemicals. The irony is hard to miss. And don’t get me started on commercial smoothies and meal replacement shakes. These get positioned as whole food nutrition in a bottle. But look at the ingredient list. Protein isolates, gums, stabilizers, seed oils, synthetic vitamins sprayed onto a matrix of processed ingredients. The same goes for most commercial plant milks. A plain oat milk made from oats and water may be fine, if not a little bit high in sugar, but the vanilla protein oat milk with dipotassium phosphate, gellan gum, and “natural flavors” is an ultra-processed product wearing a health costume.

The food industry has gotten remarkably good at this. They understand that health-conscious consumers read labels, so they use words like “plant-based,” “clean,” “simple ingredients,” and “wholesome” on packaging that contains ingredients no human kitchen has ever stocked. The packaging is doing exactly what it’s designed to do, make you feel good about buying something that serves the manufacturer’s bottom line, not your health.

So here’s a question: does any of this matter? Maybe ultra-processed foods are just a convenient way to eat, and the health concerns are overblown? The research says otherwise, and what’s emerging in 2026 goes far beyond what we knew even a few years ago. The landmark study that changed this conversation came from an NIH trial published in Cell Metabolism in 2019. Researchers admitted 20 adults to the NIH Clinical Center and randomly assigned them to eat either an ultra-processed diet or an unprocessed diet for two weeks, then switched them to the other diet for two more weeks. The meals were carefully designed to be matched for calories, energy density, macronutrients, sugar, sodium, and fiber.

On paper, the two diets were nutritionally identical. The only difference was the degree of processing. The results were striking. On the ultra-processed diet, people ate an extra 508 calories per day without being told to eat more. They didn’t report being hungrier. They weren’t eating out of boredom or emotional distress. They just ate more spontaneously, consistently, day after day. They gained about two pounds in two weeks, and when they switched to the unprocessed diet, they lost that same weight. Same calories available, same macros, same fiber, but the processing itself drove overconsumption. Something about the way food was manufactured bypassed normal satiety signals. Think about what that means. These weren’t people choosing fast food over salads. They were eating meals that were nutritionally matched by design. The researchers controlled for everything the conventional framework says matters, and the ultra-processed foods still caused overconsumption and weight gain. If that doesn’t make you question the “a calorie is a calorie” dogma, I don’t know what will.

In this episode, Chris explores the hidden effects of ultra-processed foods—from disrupted satiety signals and overeating to changes in the gut microbiome, inflammation, metabolic dysfunction, and the gut-brain axis. The takeaway? How food is processed matters more than the nutrients listed on the label #ChrisKresser #UPFs

The recent 2026 Tufts study took this much further. The team, led by researchers at the Friedman School of Nutrition and Policy, analyzed data from 48,000 adults across 10 NHANES cycles from 1999 to 2018, linked to the National Death Index. They found that every 10 percent of daily calories from ultra-processed foods was associated with higher BMI, higher HbA1c, a marker of average blood sugar, higher diastolic blood pressure, greater prevalence of metabolic syndrome, greater prevalence of diabetes and cancer, and a 4 percent higher risk of dying during the study period.

But here’s what matters most. When they adjusted for saturated fat, added sugar, and sodium, the usual suspects that mainstream nutrition blames for poor health, it barely budged the results. The associations remain. When they adjusted for overall nutritional quality using a comprehensive metric called the Food Compass Score, the associations were only partially attenuated. They still remain significant. This is a big deal. The entire edifice of mainstream dietary guidance is built on the nutrient reduction model. The assumption is, if you control for the nutrients, you’ve controlled for the health effects of the food. Eat less saturated fat, less sugar, less sodium, and you’ll be fine. It’s the framework behind the Nutrition Facts panel, behind the Dietary Guidelines for Americans, behind virtually every public health message about food for the past 50 years. What this study is saying is, no, that’s incomplete. Something about the processing itself, independent of the nutrient profile, is driving these health outcomes. The researchers specifically tested this by adjusting for every nutrient-based metric they could, and the associations held. The model that dominates public health nutrition can’t explain what’s happening.

A separate 2024 prospective cohort study in the Journal of the Academy of Nutrition and Dietetics, also from that Tufts group, reinforced these findings. In almost 40,000 adults followed for a median of eight years, each 10-point increment in a percentage of calories from UPFs was associated with a 9 percent higher risk of death from any cause. And it wasn’t evenly distributed across all UPF categories. Sugar-sweetened beverages, ready-to-eat mixed dishes, ultra-processed dairy products, and ultra-processed oils and sauces were the biggest drivers. Interestingly, ultra-processed vegetables and legumes were associated with a reduced risk, which suggests that not all ultra-processing is equally harmful, and that the base food still does matter. In a meta-analysis in eClinicalMedicine that pooled 20 studies with over 1.1 million participants and nearly 60,000 cardiovascular events, found a linear dose-response relationship between UPF intake and cardiovascular events. More ultra-processed food, more heart attacks and strokes. No safe threshold, just a steady linear climb in risk with every additional serving.

So, what’s going on here? If it’s not just the nutrients, what is it about processing that causes harm? This is where I think the metaphor of a building helps. Think of a whole food, like an apple, a piece of fish, a handful of nuts, as a building with an intact structure. The walls, the floors, the wiring, the plumbing all work together. The nutrients are the furniture inside. Now imagine you demolish that building, salvage some of the furniture, tossed in some synthetic materials, and reassembled it into something that looks like a building from the outside. On an inventory sheet, you might check off similar furniture. But the structure that made it a functional building is gone. That’s what ultra-processing does to food. It destroys the food matrix, the cellular structure that determines how nutrients are released, absorbed, and metabolized. When you eat a whole almond, the cell walls control how quickly fats and proteins are released during digestion. Your body has to do work to break those cells open, and that process takes time, which means the nutrients enter your bloodstream gradually. Your satiety hormones fire appropriately, and the undigested fiber reaches your lower gut, where it feeds beneficial bacteria. When you eat almond butter, those cell walls have been mechanically disrupted, so absorption is faster. When you eat a protein bar with almond protein isolate, the cellular structure has been completely obliterated. Same nutrients on the label, completely different biological experience in your body.

This is the piece that mainstream nutrition keeps missing. A nutrition facts panel can tell you how many grams of protein, fat, and carbohydrates are in food. It can’t tell you anything about the food’s structure, about how those nutrients will behave once you eat them, about whether they’ll feed your gut bacteria or starve them, about whether they’ll trigger appropriate satiety or bypass it entirely. The label is measuring the furniture, not the building.

There are several mechanisms now supported by research. First, ultra-processed foods alter the gut microbiome. A 2025 review in Nutrients found that UPFs are associated with decreased microbial diversity, lower levels of beneficial bacteria, and an increase in pro-inflammatory microorganisms. The synthetic additives and emulsifiers in these foods appear to disrupt the gut barrier, increasing intestinal permeability, what’s sometimes called leaky gut. This triggers chronic low-grade inflammation, which is now recognized as a driver of metabolic syndrome, type 2 diabetes, cardiovascular disease, and even some cancers.

Second, the processing itself generates harmful compounds. A 2026 study in Food Chemistry found that ready-to-eat beef, compared to freshly cooked beef from the same source, caused significantly more oxidative stress in rats. The oxidized proteins in the processed meat increased colon oxidation markers by more than fourfold, shifted gut microbiota composition dramatically, and altered their colonic metabolome in ways associated with poor gut health. Again, the raw ingredients were the same, the processing changed everything.

Third, there’s the issue of food additives that serve no nutritional purpose. Some emulsifiers, like carboxymethylcellulose, which is common in processed foods and many health foods, have been shown to erode the mucus layer that protects the intestinal lining. Non-nutritive sweeteners alter the gut microbiome in ways we’re only beginning to understand. And then there are contaminants from processing and packaging– microplastics, phthalates, bisphenols, and other chemicals that leach from packaging into the food itself.

Fourth, there is growing evidence that ultra-processed food consumption affects the gut-brain axis. The same 2025 Nutrients review noted that UPFs may alter communication between the gut and the brain, potentially affecting cognitive function and mental health. When you consider that about 95 percent of the body’s serotonin is produced in the gut, and that the microbiome directly influences serotonin production, it starts to make sense why diets high in ultra-processed food are associated with higher rates of depression and anxiety in epidemiological studies. We’re only beginning to understand these connections, but the early data is concerning.

Many of these mechanisms compound. A food that disrupts the gut barrier also alters the microbiome. An altered microbiome increases inflammation. Chronic inflammation drives insulin resistance. Insulin resistance contributes to weight gain and metabolic syndrome. You end up with a cascade of dysfunction that starts with the food you’re eating but extends into nearly every system in the body. This is exactly why functional medicine has always taken a systems-based approach to chronic illness, and it’s why you can’t fix these problems by just switching from one brand of protein bar to another. This is why the focus on macronutrients and calories misses the point entirely. You can have two meals with identical macronutrient profiles, identical calorie counts, identical fiber content, and one of them will drive overconsumption, inflammation, gut dysbiosis, and metabolic dysfunction while the other one won’t. The variable isn’t the nutrients, it’s the processing.

For anyone who’s been paying attention to functional medicine, again, this shouldn’t come as a surprise. We’ve been saying for decades that food quality matters most, that you can’t reduce a food to its constituent parts and expect to understand its effects on health. But it’s deeply satisfying and, frankly, a little frustrating to see mainstream research finally catch up. Frustrating because millions of people have been given dietary advice based on the nutrient reductionist model for years, told to eat low-fat yogurt and whole grain cereal and lean protein bars, all of which are ultra-processed, while being warned away from eggs and butter and full-fat dairy, which are minimally processed whole foods. The conventional dietary guidelines have been optimizing for the wrong variable this entire time.

So, what do you do with this information? I want to be practical here because knowing that ultra-processed food is harmful doesn’t help you unless you know how to make changes that are sustainable. The good news is this doesn’t require a radical overhaul of your life unless you’re one of those Americans that’s eating 60 percent of calories from ultra-processed food. It requires a shift in how you evaluate what you eat. So here are several practical steps. First, apply the bag or box test. If it comes in a bag or a box, take a closer look. That doesn’t mean everything in a bag or box is harmful. Frozen vegetables, dried lentils, canned sardines, these are minimally processed and perfectly healthy. But if the ingredient list includes substances you’ve never cooked with at home, things like maltodextrin, soy protein isolate, modified food starch, or any of the various gums and emulsifiers, that’s an ultra-processed food. A useful rule of thumb: if your grandmother wouldn’t recognize an ingredient, or if you couldn’t buy it at a farmer’s market, it’s probably an ultra-processing marker.

Second, be skeptical of health halo foods. Protein bars, plant-based meat alternatives, flavored probiotic drinks, commercial smoothies, most plant milks with added protein and stabilizers, granola marketed as “clean” or “wholesome,” these are the foods most likely to fool health-conscious people. Read the ingredient list, not the marketing.

Third, build your diet around whole, minimally processed foods. Vegetables, fruits, high-quality animal proteins, eggs, nuts, seeds, properly prepared legumes and whole grains if you tolerate them, fermented foods like sauerkraut and yogurt made from simple ingredients. Cooking at home, even simple cooking, almost always produces a less processed meal than anything you can buy pre-made. And I want to push back on the idea that cooking at home is too time-consuming or complicated. A piece of salmon with roasted vegetables takes 25 minutes. A slow cooker stew with whole ingredients takes 15 minutes of active prep and then cooks itself while you go about your day. Scrambled eggs with sautéed greens takes 10. A big salad with canned sardines, olive oil, and lemon takes five. These aren’t gourmet projects, they’re meals that our parents and grandparents made every day without thinking twice.

Fourth, pay attention to cooking oils and fats. Many ultra-processed foods are made with industrial seed oils like soybean, canola, and sunflower because they’re cheap and shelf-stable. When you cook at home, use olive oil, avocado oil, butter, ghee, or coconut oil. This single switch eliminates one of the most pervasive ultra-processing ingredients from your diet.

Fifth, don’t let perfection stop you from making progress. If you currently eat a diet that’s 60 percent ultra-processed, the American average, you don’t need to go to zero overnight. Start by swapping out the biggest offenders: the breakfast bars, the flavored yogurts, the ready-to-eat mixed dishes, the seed oils. Every swap from ultra-processed to minimally processed is moving you in the right direction. And sixth, rethink breakfast. For many people, breakfast is the most ultra-processed meal of the day. Cereal with skim milk, protein bar on the way to work, commercial smoothie. Compare that to eggs scrambled in butter with some sautéed vegetables, or full-fat plain yogurt with fresh berries and a handful of walnuts. The second option is simpler, faster than most people think, and orders of magnitude less processed. If you change nothing else, changing breakfast alone can shift a significant percentage of your daily calories away from ultra-processed sources.

I also want to acknowledge that this is harder for some people than others. Ultra-processed foods are cheaper, more convenient, and more widely available than whole foods in many communities. That’s a systemic problem, not an individual failing. The American Journal of Public Health Special Edition I mentioned earlier made exactly this point, calling for policy changes, including mandatory front-of-package warning labels for ultra-processed foods, reforms to agricultural subsidies, and changes to school meal programs. These are conversations we need to be having at a societal level, but at the individual level, the evidence is clear. Reducing your intake of ultra-processed food, even modestly, is one of the most impactful things you can do for your long-term health.

I think the biggest takeaway from this research isn’t a specific nutrient to avoid or a specific food to eat more of, it’s a shift in how we think about food entirely. For decades, mainstream nutrition has been obsessed with reductionism, breaking food down into its component parts– this many grams of protein, this many milligrams of sodium, this many calories. The ultra-processed food research tells us this framework is fundamentally incomplete and wrong. Food is more than the sum of its nutrients. The structure, the matrix, the way the food was prepared and processed, all of it matters. And ignoring that has contributed to exactly the chronic disease epidemic we’re trying to solve. Eat real food. It really is that simple.

Thanks for listening. You can find show notes and links to all the studies I mentioned at ChrisKresser.com. If you have questions about this episode or suggestions for future topics, head over to ChrisKresser.com/podcastquestion and leave me a message. I read all of them, and your questions help shape the content I create. I’ll talk to you next time.