Everyone’s talking about ultraprocessed foods — but what exactly are they?

What makes ultraprocessed foods different?

Processed food is as old as food itself: As some food industry apologists are quick to point out, almost everything we eat is processed in some way, and many foods are inedible without some level of processing. Because “processing” technically refers to any changes we make to food in its most basic state — even cutting it into pieces or cooking it at home — this observation is technically true, but erases important distinctions about the varying degrees and purposes of the processing that ingredients are subjected to. The current conversation on ultraprocessed foods is dealing with the extreme end of the spectrum.

The term “ultraprocessed” originated with a group of Brazilian researchers who were trying to understand why, even though sales of sugar and other ingredients traditionally considered “fattening” were falling, obesity rates within the country were rising, a trend echoed across the world.

Their research into dietary patterns led them to develop what they called the Nova system, which separates foods into four different categories based on degree of processing. Group 1 foods are whole foods, along with ingredients that have been processed with simple techniques like grinding, cutting, drying or fermentation, such as flour, yogurt and dried fruits. Group 2 foods are the product of slightly more intensive processing and refining: oils, sugars, starches and other isolated ingredients. These first two ingredient groups might remove an inedible portion of a food or separate out a more desirable part of it, but they don’t contain other additives.

Products that combine foods from Groups 1 or 2 fall into Group 3, which includes canned goods, preserved products with added salt and sugar like bacon, jerky and jams, and foods like fresh breads, cheeses, wine and beer. The addition of non-food industrial ingredients, like stabilizers, gums, chemical preservatives, flavorings and more moves foods into Group 4, the ultraprocessed foods. These foods may contain no Group 1 foods at all, and are often formulated entirely from other processed and isolated ingredients like modified food starches or proteins. Many of the processing steps used in Group 4 foods aren’t commonly used at home, like prefrying, extrusion and hydrogenation.

The Brazilian researchers found that, over the second half of the 20th century, households had begun buying more and more of these Group 4 foods. And while people were buying less and less sugar, butter and oil, the worsening health outcomes the researchers saw were largely the result of the shift toward ultraprocessed foods, which often had far higher calorie and sodium counts than people realized in part because they weren’t preparing them themselves.

The Nova system doesn’t claim to measure the nutritional value of foods; not all Group 4 ultraprocessed foods are intrinsically unhealthy. Take supermarket breads, for example. On a recent episode of the podcast “Pressure Cooker,” Chris van Tulleken, author of 2023’s “Ultra-Processed People,” outlined that most breads in the supermarket are, by definition, ultraprocessed — they tend to include preservatives, enzymes and other additives that allow them to last on a shelf for more than a day or two. But some are made of white flour with refined sugars, salts and fats, while others are made from whole grains, seeds and other whole-food ingredients. Both are nominally ultraprocessed, but the inclusion of more whole food ingredients and fewer additional sugars means the latter is clearly a better option than the former.

It’s also the purpose of certain types of processing that makes many UPFs problematic. The poster child UPFs — think chips, nuggets, cookies and soft drinks — don’t just contain additives that extend their shelf life, but they’re also engineered to be delicious. That “hyperpalatbility” is part of what makes UPFs so easy to overconsume: The excess salt and sugar, in combination with highly engineered flavorings, might convince our brains to eat more of these junk foods, even when they have little to offer us nutritionally. It doesn’t help that UPFs are often sold in “family size” packages that make it that much easier to keep eating them.

So what are the problems with eating ultraprocessed foods?

Some of the problems associated with UPFs simply come from the fact that high fat, sugar and sodium content make many of them an unbalanced addition to most people’s diets. Diets high in UPFs are higher in fats and sugars than those that center whole foods, and this contributes to obesity and diabetes.

But the issues with UPFs are a little more complicated than just their excessive calorie counts. By design, most food processing changes how nutrients will be absorbed by our bodies, and is crucial for making some foods digestible at all. But too much processing ends up being counterproductive: Extensively processed foods get stripped of vitamins and minerals as their ingredients become more refined, and they often lack the fiber that helps us feel full, aids regular bowel movements and feeds healthy gut bacteria. Certain additives can also have inflammatory effects on the digestive system and impair the function of beneficial bacteria. UPF consumption has been associated with inflammatory bowel disease, irritable bowel syndrome and even colorectal cancer.

And given the way our gut health affects the rest of our bodies, this means that there are also associations between high UPF consumption and a range of other problems, from cardiovascular disease to anxiety and depression. One recent study analyzed the diets and health outcomes of over 100,000 participants over a 30-year window, finding that the highest consumers of UPFs had a significantly higher mortality rate than the lowest consumers.

Of course, there are reasons to take these results with a grain of salt: It’s hard to separate out UPF consumption from other correlated factors that also contribute to poor health, like low physical activity and poverty. Often, it’s constraints on time, resources and money that make UPFs so appealing to shoppers in the first place. But the evidence is strong enough that many medical groups have advised consumers to limit their consumption of UPFs (particularly processed meats and high-sugar foods and beverages) wherever they can and prioritize the consumption of whole foods.

How to avoid ultraprocessed foods

Limiting UPFs is easier said than done: While avoiding the most obvious offenders is simple enough, there are a lot of ultraprocessed foods lurking outside the snack and cookie aisles. However, following a few simple rules can help you limit your intake. The easiest thing to do is a quick scan of the ingredient list. The old advice to “not eat anything you can’t pronounce” has its problems — there are plenty of perfectly safe ingredients that have complicated chemical names — but if you’re trying to avoid ultraprocessed foods, it’s a good rule of thumb to steer clear of things you wouldn’t find in your own kitchen. Products with long ingredient lists, especially those that include several different oils, gums, stabilizers, emulsifiers or preservatives, are quite likely to be ultraprocessed.

Many products, like yogurt, come in a range of processing levels, from plain yogurts that include only milk and active bacterial cultures to ultraprocessed versions with added sugars and flavorings. Try to opt for the simplest version of a given product that you can find.

Ironically, health claims, like “low sugar,” “low fat” or “reduced sodium,” are often flags that a product is ultraprocessed. These claims may well be true, but they can also be an indicator that the product is a complex formulation of ingredients, and sometimes the things that make those claims true — like artificial sweeteners — guarantee that a food is ultraprocessed. Occasionally, even Group 1 foods will be marketed this way to get in on a trend: Plain Greek yogurt, a minimally processed food, might carry a “high protein” label. But that label will be more common for UPFs with whey or plant protein isolates added during processing, so it’s still important to scan the ingredient list.