A two-year randomized weight loss trial comparing a vegan diet to a more moderate low-fat diet

Objective: The objective was to assess the effect of a low‐fat, vegan diet compared with the National Cholesterol Education Program (NCEP) diet on weight loss maintenance at 1 and 2 years. Research Methods and Procedures: Sixty‐four overweight, postmenopausal women were randomly assigned to a vegan or NCEP diet for 14 weeks, and 62 women began the study. The study was done in two replications. Participants in the first replication (N = 28) received no follow‐up support after the 14 weeks, and those in the second replication (N = 34) were offered group support meetings for 1 year. Weight and diet adherence were measured at 1 and 2 years for all participants. Weight loss is reported as median (interquartile range) and is the difference from baseline weight at years 1 and 2. Results: Individuals in the vegan group lost more weight than those in the NCEP group at 1 year ?4.9 (?0.5, ?8.0) kg vs. ?1.8 (0.8, ?4.3); p < 0.05] and at 2 years ?3.1 (0.0, ?6.0) kg vs. ?0.8 (3.1, ?4.2) kg; p < 0.05]. Those participants offered group support lost more weight at 1 year (p < 0.01) and 2 years (p < 0.05) than those without support. Attendance at meetings was associated with improved weight loss at 1 year (p < 0.001) and 2 years (p < 0.01). Discussion: A vegan diet was associated with significantly greater weight loss than the NCEP diet at 1 and 2 years. Both group support and meeting attendance were associated with significant weight loss at follow‐up.