Overview
- Researchers analyzed dietary records from a randomized cross-over trial and published the secondary findings in Frontiers in Nutrition on Nov. 18, 2025.
- Sixty-two adults with excess weight followed a low-fat vegan diet and a Mediterranean diet for 16 weeks each with a four-week washout and no calorie limits.
- Overall plant-based diet index (PDI) scores rose on the vegan plan but not on the Mediterranean plan, while the unhealthful PDI (uPDI) increased on vegan and decreased on Mediterranean.
- Increases in PDI and uPDI—changes seen only with the vegan diet—were associated with weight loss, whereas shifts in the healthful PDI (hPDI) were not tied to weight change.
- Authors attribute the effect mainly to removing animal products and reducing added oils and nuts, noting that weight loss occurred even when refined grains and potatoes increased.