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One of the biggest boogeymen around these days is ultraprocessed food. You can see dozens if not hundreds of news articles every week decrying the damage that these foods are doing to our health. UPFs are apparently responsible for everything from dementia to heart disease and virtually every other health problem in between. They’re so bad that the U.S. Food and Drug Administration is considering “taking action” against UPFs to stop Americans from eating them.
If you’re a lover of hot dogs, it’s probably been a pretty terrifying couple of years. But despite what you may have heard, well, everywhere, the truth is that we have never really defined what a UPF is and we still don’t have good evidence that food processing is itself bad for your health.
The first issue takes us back to the creation of the term “ultraprocessed food.” Researchers in Brazil introduced the term in a 2009 paper as part of the Nova grading system, a classification framework to help determine the processing level of food. It draws a distinction between what they consider to be “food” and “ultra-processed food products.” But what does the term “ultra” even mean?
For one thing, there’s very little grading of processing. Foods are either unprocessed, minimally processed, or ultraprocessed. Some versions of the Nova scale also include “processed” food as a third level in between minimally processed and ultra. But that leaves a huge gap. Things become either ultraprocessed or not, which dichotomizes food into good vs. bad. A more realistic grading might see us talk about moderately processed, heavily processed, very heavily processed, and then ultraprocessed, or something similar. We might also consider completely removing the term ultra because it is weirdly emotional and sounds more like a meme than science.
This is a fundamental limitation with Nova. The scale—which is used for virtually all research on UPFs—does not measure food processing at all. It does not look at how many industrial processes a food requires to end up on your shelves. Instead, it measures what researchers think a UPF should look like. Most studies simply get three or four researchers together to discuss how they should define UPFs in that piece of research.
In the original 2009 paper, the concept was that any food which required some form of cooking—including bread, cured sausages, corn chips, etc.—would be considered an “ultra” processed food product. But this is obviously absurd. Very few people would consider a fresh bakery loaf to be “ultra” processed. You see this throughout the UPF literature, with many studies grouping foods differently based largely on the opinions of the researchers involved.
I like to give a solid example of this: corn chips. You can very easily make salted corn chips at home with some corn flour, oil, and salt. I’ve done it before, it’s delicious. Most plain corn chips should therefore be considered minimally processed, because they take almost no processing to make.
But that’s not what happens. In practice, corn chips are generally considered to be UPFs regardless of how much they are actually processed. The concept of “ultra” processing has nothing to do with the actual amount of processing that foods undergo.
You can see this in the writing of professor Carlos Augusto Monteiro, who is the researcher behind the Nova classification. In one 2017 paper, he and his team explicitly say that food processing is not the issue, as all foods are processed. Rather, the problem is foods being “separated from nature,” with UPFs being “branded,” “convenient,” “highly profitable,” and “usually packaged attractively and marketed intensively.” If that all sounds vague and subjective to you … well.
There’s also the evidence side of things. As I’ve written before, most of the research showing that UPFs are bad for health is low-quality and very misleading. The majority of the studies on UPFs that make headlines are observational papers looking at associations between self-reported food intake and health outcomes—these tell us little about whether UPFs actually cause ill health.
And the most robust studies—randomized trials where people are given either “ultra” processed or less processed diets to eat—show few negative impacts. At worst, eating a diet of 100 percent UPF compared to a diet with no UPF might cause you to gain a few pounds, but even that is uncertain.
And even this is contested. A recent paper in the journal Science argued that even the modest negative effects seen in some of these randomized trials are probably down to differences between UPF diets and less processed diets that have nothing to do with the processing. For example, most of the UPF diets provided in these studies have higher energy density—meaning more calories per bite of food—which is known to cause people to gain a bit of weight. Even though the studies are in theory comparing diets that are identical except for the processing, in practice the UPF diet generally ends up being gummy bears and ice cream while the minimally processed diet has yogurt and fresh fruit. It’s not hard to see how this could impact which diet people eat a bit more of.
This is why in its 2025 guidance, the U.K.’s Food Standards Agency largely discarded the concept of UPFs. After a detailed scientific review, they found that UPFs include many foods that are unhealthy, but others that are not. Their advice was not to focus on processing, but to “try to follow a healthy diet, which for most people means cutting down on how much saturated fat, sugar and salt you eat and eating more vegetables and fibre.” The key problem here is, and has always been, that the term UPF is almost entirely meaningless. We do not define ultraprocessed foods based on how much they are processed—instead, the definition is more about subjective opinions. It’s probably not a great idea to regulate your entire food system based on vibes.
