A clinical trial led by researchers at University College London (UCL) and UCLH has revealed that participants who consumed minimally processed foods (MPF) lost twice as much weight compared to those who ate ultra-processed foods (UPF), despite both diets being nutritionally matched. The study, published in Nature Medicine, is significant for being the longest experimental examination of UPF diets and the first to assess the effects of MPF versus UPF in real-world conditions.
The trial involved 55 adults who were divided into two groups, each following an eight-week diet of either MPF or UPF, with a four-week washout period in between. The diets were designed to align with the UK’s Eatwell Guide, ensuring balanced levels of macronutrients and other dietary components. Participants were provided with ample food and instructed to eat freely.
Results indicated that the MPF diet led to a 2.06% weight reduction, while the UPF diet resulted in a 1.05% reduction, correlating to calorie deficits of 290 and 120 kilocalories per day, respectively. Notably, the weight loss from the MPF diet was attributed to a decrease in fat mass and total body water, without affecting muscle or fat-free mass.
Additionally, participants on the MPF diet reported significantly improved craving control compared to those on the UPF diet. The study's authors emphasized the role of food processing in health outcomes and advocated for policy changes to improve food environments, suggesting that healthier options should be made more accessible.
The researchers acknowledged the need for further studies to explore the long-term impacts on health markers associated with these diets. Overall, the findings support the idea that adhering to nutritional guidelines and choosing less processed food options may promote better weight management and health outcomes.