Nowadays, the lighting in any supermarket feels almost clinical, with rows of identical packaging and ingredient lists written in unreadable fonts. It’s difficult to ignore how much of the food on those shelves belongs to what scientists now refer to as ultra-processed food. And for the past few years, that label has carried a lot of weight because it has been connected in study after study to heart disease, obesity, and early mortality. The science appeared to be settled. However, it isn’t.
A question that has been quietly circulating among nutrition researchers is raised by a close examination of ultra-processed food review science, particularly the five randomized controlled trials carried out in the United States, the United Kingdom, Denmark, and Japan: are ultra-processed foods truly harmful because of their manufacturing process or just because of what they contain?
The difference is more important than it might seem. Under carefully monitored conditions, participants in these trials—which are considered the gold standard of nutritional research—were fed either highly processed or minimally processed diets. Participants who followed ultra-processed diets consumed 500–800 more calories daily than those who ate whole foods when they were allowed to eat at will. They put on weight. Then came headlines. However, the process that led to that weight gain was rarely examined as closely as the result.
The majority of what occurred seems to be explained by two factors: food texture and calorie density. Because ultra-processed foods are typically softer, people tend to chew less, eat more quickly, and consume more before feeling satisfied. Additionally, they typically contain more energy in the same amount of space, making them more calorie-dense. Researchers reported that in a different feeding experiment, participants’ daily energy intake increased by 600 to 800 calories when calorie density was simply increased by 0.45 kilocalories per gram without their knowledge. These are potent effects that are independent of whether food was prepared in a kitchen or a factory.
The picture was further complicated by one eight-week trial that took place in the UK. The ultra-processed diet was created by researchers while adhering to national nutritional guidelines, which include controlled calorie density, appropriate fat distribution, and sufficient fiber. Although it was marginally less than the non-processed comparison diet, participants did lose weight on it. For a straightforward story, the outcome was inconvenient. It implied that the contents of a processed food are far more important than the industrial method used to produce it.
Some researchers believe that the narrative surrounding highly processed foods has surpassed the available data. Mass-produced soft drinks and some whole-grain breads are grouped together under the NOVA classification system, which classifies foods according to their level of processing. That’s a broad net that includes some foods that are nutritionally neutral or even helpful in addition to those that actually cause harm. Whether the label is a helpful policy tool or an idea that has become too simplistic to be truly instructive is still up for debate.
Another twist was introduced by the fixed-calorie trials. The non-processed diet still produced better weight results when calories were kept constant and ultra-processed foods were contrasted with high-fiber substitutes. However, a large portion of that benefit was due to the increased fiber content, which decreased the amount of calories the body actually absorbed, rather than any enigmatic processing characteristic. Fiber just functions. It is frequently eliminated by ultra-processing. There is a nutritional solution to that nutritional issue.
The science is gradually showing that dietary policies based on processing categories may be misguiding people. The factors that consistently predict harm include low fiber, high calorie density, soft texture, and excess sodium. They frequently, but not always, travel with highly processed foods. As this research progresses, it becomes evident that the food industry has legitimate issues to address; these issues may not be precisely what the general public believes.
