A vegetarian dietary pattern may be the most effective for weight loss, according to a meta-analysis published in the Journal of General Internal Medicine. Researchers at Harvard, in conjunction with researchers in Taiwan, reviewed 12 randomized controlled trials, with and without calorie restrictions, encompassing 1,151 participants assigned to various vegetarian and non-vegetarian weight-loss diets.

Over an average of 18 weeks, vegetarian participants lost 4.4 pounds more on average than those following non-vegetarian diets. Those assigned vegan diets lost 5.5 pounds more on average, the most weight loss of any dietary group. Increased intakes of fruits, vegetables, and whole grains provide more fiber, phytochemicals, and minerals that may contribute to weight loss.

Another recent meta-analysis conducted by researchers at the Physicians Committee found that people who adopted vegetarian and vegan diets without calorie restrictions lost an average of 7.5 to 10 pounds.

Huang RY, Huang CC, Hu FB, Chavarro JE. Vegetarian diets and weight reduction: a meta-analysis of randomized controlled trials. J Gen Intern Med. Published online July 3, 2015.