Can You Lose More Weight Eating the Same Calories-Just Less Processed? Study Sheds Light

Despite both diets being designed to meet the UK government’s Eatwell Guide in terms of calories, fat, salt, and fibre, weight loss was significantly higher on the MPF diet.

Participants on the MPF diet lost an average of 2.06% of their body weight, compared to just 1.05% on the UPF diet. The MPF group also experienced greater reductions in fat mass and total body water, while maintaining muscle mass—indicating healthier body composition.

The MPF diet also improved participants' ability to resist cravings, particularly for savoury foods.

"The primary outcome of the trial was to assess percentage changes in weight, and on both diets, we saw a significant reduction, but the effect was nearly double on the minimally processed diet. Though a 2% reduction may not seem very big, that is only over eight weeks and without people trying to actively reduce their intake. If we scaled these results up over the course of a year, we'd expect to see a 13% weight reduction in men and a 9% reduction in women on the minimally processed diet, but only a 4% weight reduction in men and 5% in women after the ultra-processed diet. Over time this would start to become a big difference," said Dr. Samuel Dicken, first author of the study from the UCL Centre for Obesity Research and UCL Department of Behavioural Science & Health.

Though the trial found no significant negative effects from the UPF diet on blood markers, experts stress the long-term benefits of reducing food processing.

Reference: Dicken, S. J., et al. (2025). Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial. Nature Medicine. doi.org/10.1038/s41591-025-03842-0.