April 3, 2006 -- When people want to lose weight, going vegetarian might be an advantage.
The finding comes from Susan Berkow, PhD, CNS, and Neal Barnard, MD, of the Physicians Committee for Responsible Medicine (PCRM), a nonprofit group that supports vegetarian diets.
The reviewed studies generally used the word "vegetarian" for people who avoid meat but consume dairy products and eggs. "Vegans avoid all food products of animal origin," write Berkow and Barnard.
The review is due to appear in April's edition of Nutrition Journals.
More Weight Lost
In weight loss studies, participants who had been randomly assigned to follow vegetarian or vegan diets lost more weight than those not on vegetarian diets.
Those studies were short and typically featured low-fat vegetarian diets. In several studies, participants were asked not to change their exercise habits. That way, their weight loss would have stemmed from diet, not extra exercise.
The review also included observational studies, in which participants weren't asked to change their diets. The observational studies showed that up to 6% of vegetarians were obese, compared with 5%-45% of nonvegetarians, and that vegetarians tended to weigh less than nonvegetarians.
Were those differences due to diet, or were other factors (such as exercise) important? The review doesn't provide the details of every study that was reviewed, so that's not clear.