Though several randomized controlled trials have investigated the effects of ultraprocessed foods (UPF) on obesity, leading to news coverage that suggests ultraprocessing is inherently harmful, the reality is different, according to the authors of this Perspective. Based on the design of clinical trials conducted to date, it is very difficult to attribute negative effects observed in trial participants to ultraprocessing. Instead, these effects are likely due to differences in traditional nutritional properties that UPFs frequently exhibit – including soft textures (which can lead people to eat more and faster), high calorie density, high amounts of saturated fat and salt, and low fiber and protein content. These properties affect health regardless of the extent of food processing, Faidon Magkos and colleagues say. The authors describe the five clinical trials conducted so far on UPFs in the USA, UK, Denmark, and Japan, outlining the trials' methods, variable findings, and limitations. "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," Magkos et al. write. They note that the UPF concept encompasses many foods that are unhealthy, but also foods that are not necessarily harmful and even some that are beneficial. Based on evidence from the trials, they recommend that policy guidance around UPFs should focus on distinguishing nutritionally poor, calorie-dense, and rapidly consumed foods – regardless of their degree of processing.
Podcast: A segment of Science's weekly podcast with Faidon Magkos, related to this research, will be available on the Science.org podcast landing page after the embargo lifts. Reporters are free to make use of the segments for broadcast purposes and/or quote from them – with appropriate attribution (i.e., cite "Science podcast"). Please note that the file itself should not be posted to any other Web site.
