HMN 2026: What are the limits of evidence from ultraprocessed food trials

A group of eating behavior and metabolism experts from across Europe have published a Perspective article in the journal Science examining the limitations of current evidence on ultraprocessed foods (UPFs).

The authors include Professor Eric Robinson (Department of Psychology, University of Liverpool), Professor Faidon Magkos (Department of Nutrition, Exercise and Sports, University of Copenhagen), and Professor Ciarán G. Forde (Sensory Science and Eating Behavior, Division of Human Nutrition and Health, Wageningen University).

Although several randomized controlled trials have explored the effects of UPFs on obesity—leading to widespread claims that ultraprocessing is inherently harmful—the authors argue that the evidence does not support this conclusion.

They explain that, based on the design of existing clinical trials, it is difficult to attribute any negative health effects observed directly to ultraprocessing itself. Instead, these outcomes are more likely driven by common nutritional characteristics of UPFs, including:

• Soft texture, which may lead people to eat more and more quickly
• High calorie density
• High levels of saturated fat and salt
• Low fiber and protein content.

The authors emphasize that these factors can influence health regardless of how processed a food is.

The article reviews five clinical trials conducted in the U.S., UK, Denmark and Japan, highlighting their methods, varied findings, and key limitations.

Professor Eric Robinson said, “Collectively, available randomized controlled trials provide weak support for an ultraprocessing-specific effect of UPFs on body weight regulation and cardiometabolic function that is independent of established nutritional determinants.”

The authors also note that the UPF category includes a wide range of foods, from those that are clearly nutritionally poor to others that are not necessarily harmful, and some that are likely beneficial for health based on their nutritional content.

Based on current evidence, they recommend that policy guidance should focus less on the degree of processing and instead prioritize identifying foods that are nutritionally poor, calorie-dense, and rapidly consumed.

The content is provided for information purposes only.