Report compares UPF nutritional profile and processing as health drivers

A commentary report from Perspectives has interpreted results from multiple studies on ultra-processed foods (UPFs) and their link to obesity and other diseases. The industrial production of food processing has been hypothesized to lead to harmful products, even if the food has a healthy nutritional profile, given the alteration of its natural structure and the addition of ingredients and additives. 

The authors of the report note that UPFs are commonly characterized by their high calorie density and high amounts of salt and sugar, while being low in protein and fiber, which are unhealthy characteristics of food independent of processing level.

The report in Science investigated whether the negative health effects from UPFs are caused by the foods’ processing or nutritional qualities, using data from five previously published randomized controlled trials conducted in Japan, the US, Denmark, and the UK.

Processing vs. nutritional quality

In two of the trials with obese and overweight participants (Japan and the US), diets rich in UPFs provided a higher intake of approximately 500–800 calories daily, and caused weight gain when compared to diets without such foods.

In a UK trial, obese and overweight individuals consumed either an UPF or a non-UPF diet with food adhering to the local nutritional guidelines for adequacy and healthfulness. In this trial, the group consuming UPFs had a reduced energy intake, and there was a modest weight loss observed compared to the start of the trial.

“These results suggest that a UPF-rich diet designed according to established dietary principles that emphasize nutritional quality rather than processing methods may reduce energy intake relative to habitual intake, decrease body weight, and improve cardiometabolic risk factors,” note the authors.

The authors speculate that these results could mean that ultra-processing techniques could result in an increased energy balance.However, the non-UPF group was the most beneficial approach and had a higher average weight loss.

The two remaining studies compared the two diets with a fixed calorie intake in overweight and normal-weight participants. The calorie intake was set to either meet the daily intake or exceed it, and in both trials, the UPF-consuming group showed an average weight gain, while the non-UPF group did not.

The authors speculate that these results could mean that ultra-processing techniques could result in an increased energy balance of 500 calories daily compared to non-UPF diets. However, the hypothesis that food processing would cause a metabolic effect of this magnitude is difficult to reconcile with known human physiology, they note. 

Independent researchers have commented on the article, one among whom is Dr. Sumanto Haldar, lecturer in Nutritional Sciences at Bournemouth University, UK. 

He says: “This article is a Perspective piece rather than original research – it is a secondary evaluation and commentary on several primary research [studies], consisting of randomized controlled trials on UPF and body weight changes and cardiometabolic risk.”

He notes there will be different levels of confounder adjustments in different studies, including their inherent limitations. One of the major limitations in all these trials is that they are all short in duration and chronically determined over months, rather than years.

“Therefore, we cannot make conclusive recommendations or form policies based on the current evidence.”

Calories as an outdated system

A recent report by Healthy Eating Research (HER) distinguished between different types of UPFs, arguing that certain healthier options in this category should be exempted from food policies discouraging consumers from eating them. 

The HER report argued that some ultra-processed plant-based foods may have health benefits for consumers, while animal-based UPFs and sugary drinks have consistently been found to be harmful.

Another independent researcher, Dr. Seamus Higgins, an associate professor in Food Process Engineering at the University of Nottingham, UK, says the new paper is a useful reminder that the science surrounding UPFs is far from settled.

Higgins says the greatest challenge might be that much of nutrition science still relies on calories.“The authors argue that many of the effects attributed to UPFs can be explained by well-established factors such as calorie density, fiber content, protein levels, food texture, and eating rate, rather than processing itself. Importantly, these are the same factors that emerging research into the microbiome, satiety regulation, and metabolic health increasingly identifies as key determinants of how various foods interact with human biology.”

“But the paper does raise a broader question. Have we become overly focused on food classification systems while overlooking the underlying biological mechanisms that influence health?”

He says Nova was developed as a practical four-category identifier for food processing, not as a definitive indicator for food science.

“While it has proved valuable in highlighting trends and debate in modern food production, classification is not causation. There is a danger in treating what is meant to be a descriptive framework for consumers as a definitive explanation of how foods interact with human biology,” stresses Higgins.

He says the greatest challenge might be that much of nutrition science still relies on calories – a measurement system developed more than 125 years ago to quantify the energy value of food rather than its biological effects. 

“Calories remain useful, but they were never designed to measure satiety, metabolism, microbiome interactions, hormonal responses, or long-term health outcomes. Indeed, food labeling regulations for calorific value continue to accept a degree of inaccuracy of up to [or less than] 20%, reflecting their origins as a measure of fuel value rather than biological response.”