Overweight adults ( body mass index 25-49 .9 kg/m ( 2 ) ; age 18-65 y , 19 % non-white , and 27 % men ) were randomized to a low-fat , low-glycemic index diet : vegan ( n = 12 ) , vegetarian ( n = 13 ) , pesco-vegetarian ( n = 13 ) , semi-vegetarian ( n = 13 ) , or omnivorous ( n = 12 ) .