Colorectal cancer among adults 50 and younger has increased in the last three decades. Although the disease is still rare among younger adults, researchers question whether the spike is related to the rising popularity of ultra-processed foods (UPFs).

Scientists are paying more attention to UPFs, and their findings are becoming mainstream. One study in Cell Metabolism, for example, made headlines after researchers found that participants lost weight after two weeks of eating minimally processed foods, only to gain it back when they switched to UPFs for two weeks. 

The attention surrounding UPFs has helped to educate the public on why they are unhealthy. But more than half of Americans don’t even know what qualifies as a UPF. Problematically, scientists disagree on the answer. 

Ultra Processed Foods

Among nutrition researchers, there isn’t just one way to define a UPF. A 2021 study in Trends in Food Science & Technology looked at 470 scientific articles and found 146 definitions of what it meant to be “minimally processed.”

NOVA Food Classification

Many researchers follow the NOVA classification system developed by a Brazilian research group. NOVA has four categories, placing food on a spectrum from freshest to most processed.

1. NOVA1 consists of unprocessed and minimally processed foods. This group includes all fresh fruits and vegetables, milk, eggs, meat, rice and whole grains.

2. NOVA2 typically comprises ingredients a person would keep in their fridge or pantry — butter, lard, oil, salt and sugar.

3. NOVA3 is for processed food. Canned tuna, for example, is fresh fish preserved in oil. Canned beans, frozen fruit and vegetables also fit into this category. Wine, beer and bacon are all in group three.

4. NOVA4 is reserved for UPFs. Most ready-to-eat foods fall into this category, including candies, cookies and crackers. Soda is also a category 4 item. 

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Food Category Confusion

Categorizing food types can be confusing. Where, for example, would bread and cheese go? Fresh bread and cheese would go under group three. Shredded cheese and sliced bread would go under group four.

And what about pasta? It depends on the specific item. Fresh pasta made at home with an old hand-crank pasta maker would be category one. Most dried pasta, however, would also be considered minimally processed and in the same category. Premade pastas ready for the microwave would be category four.

Most people wouldn’t be surprised that Chef Boyardee Beefaroni is a category four item. But not all of the category placements are straightforward. For example, maple syrup and honey are items one might expect in category one. But they go through processing, which puts them in category two.

It’s not just consumers who can feel confused by the categories. Researchers have also struggled to sort grocery items into the NOVA categories. 

Read More: What Science Says About the Weight-Loss Potential of The One-Meal-a-Day Diet

Dualling Definitions

Although NOVA is widely used, some researchers are concerned it’s too subjective. In a 2022 article in the European Journal of Clinical Nutrition, researchers sought to see if participants could find a consensus among which items belonged in what categories. Spoiler alert – they couldn’t agree.

The researchers recruited “evaluators” who were health and science professionals in France with at least a basic understanding of nutrition. The evaluators worked alone and were given 120 branded or 111 generic foods and asked to place them in one of the four NOVA categories.

The researchers found the process was too subjective and open to interpretation. Orange juice, for example, was placed in all four categories. More than 70 percent of the evaluators marked it as NOVA3 or NOVA4. But 26 percent of evaluators coded it as minimally or lightly processed.

The study didn’t specify whether the OJ was an organic Whole Foods version with few ingredients or the French equivalent of Sunny D made from water and high fructose corn syrup. Both types are labeled as “orange juice” and demonstrate how every product’s ingredients and production process have to be considered in the NOVA classification system.

The study also found that the NOVA descriptions were often confusing. Yogurt, for example, is listed in the official descriptions as a category-one item. However, fermented items are categorized under NOVA3, and some coders thought that because yogurt goes through a non-alcoholic fermentation process, it belongs to other processed foods. 

Read More: 4 Science-Backed Diets to Improve Your Health

Processed Food Overload

Although scientists don’t fully agree on how to define or categorize UPFs, they do agree that Americans eat too much of them. A 2021 study in Nutrients found that 80 percent of American and Canadian calorie intake comes from UPFs.

Most of the UPF calorie consumption comes from soda and, as the study authors so eloquently put it, “confectionary.” Their analysis found that the more UPFs a person ate, the less real food they consumed. A higher UPF intake was related to an increase in the amount of sugar and fat a person ate. It was also correlated with a decrease in fiber, protein, and important minerals like magnesium, niacin, potassium, zinc, and vitamins A, B12, C, D and E.

Researchers also agree that UPFs are a driving force behind weight gain and that people with a diet heavy in processed foods tend to overeat and have a higher caloric intake.

People who are ready to put down the Pop-Tarts and opt for minimally processed meals can consider the Mediterranean diet, which favors fruits, nuts, healthy oils, vegetables and whole grains. And in moderation, it also includes NOVA3 category items like wine, beer and bacon.

Read More: The Benefits of Eating a Plant-Based Diet