Macro partitioning
Adherence to a healthy vegan diet results in greater improvements in overall diet quality (HEI-2015) compared to a healthy omnivore diet, driven by higher intakes of fiber, legumes, and vegetables and lower intakes of added sugars and refined grains.
If you switch to a vegan diet, focus on increasing vegetables, legumes, nuts, seeds, and whole grains while reducing added sugars and refined grains. This study shows that a well-structured vegan diet can improve overall diet quality more than a healthy omnivore diet. Start with delivered meals or meal planning support to build skills, then transition to self-prepared meals. Ensure you monitor Vitamin B12 levels as intake drops without animal products.
Relative to baseline, mean changes in HEI total scores increased at 4 wk for both vegans (14.2) and omnivores (9.0), and these increases were largely maintained at 8 wk for both vegans (12.0) and omnivores (7.9). Differentiating factors included more legumes and fiber for vegans and more cholesterol and vitamin B-12 for omnivores.
Why this rating
Randomized controlled trial with identical twins controlling for genetics, though sample size is small (22 pairs) and duration is short (8 weeks).
Source
Diet Quality and Comparison of Plant-Based Versus Omnivore Diets in Identical Twins: A Secondary Analysis of the Twins Nutrition Study (TwiNS)
Amanda B. Zeitlin et al. · Current Developments in Nutrition · 2025
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