Two healthy menus, different weight changes.
Both supplied diets met UK guidance. The minimally processed menu produced more weight loss, but processing was not isolated.
The 30-second takeaway
Participants lost weight on both supplied menus, with a larger average loss on the minimally processed one. They could eat as much as they wanted. This tests two complete menus: it cannot neatly assign the difference to processing alone. Researchers challenged that interpretation in 2026, including concerns about menu differences and the crossover analysis.
Short-term weight change is not long-term health. Nutritional differences, treatment order and participant dropout complicate attribution to processing.
What researchers found
Weight change over eight weeks
Minimally processed / ultraprocessed menu. Difference: −1.01 percentage points, 95% confidence interval −1.87 to −0.14.
Both menus had a healthy framework
All food was provided, and both menus followed the same national dietary guidance. Participants tried them in a randomized order.
Why interpretation matters
Meeting the same guidance does not make menus identical. Published critiques question whether food processing itself explains the difference.
The original publication
Ultraprocessed or minimally processed diets following healthy dietary guidelines on weight and cardiometabolic health: a randomized, crossover trial
Samuel J. Dicken et al.
Nature Medicine · 2025
- PubMed ID
- 40760353
- Record checked
Updates and discussion
2026 critique: concerns about attributing weight change to processing ↗
2026 critique: concerns about food-processing guidance ↗
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