The vegetarian diet is becoming increasingly popular among the general population and has been accompanied by an increasing number of publications in the last twenty years. However, the spread of selective diets raises some questions, especially with regard to health. This review examines studies on vegetarianism published between 2000 and 2022 that investigated the associations between this diet, weight, and eating disorders. The descriptive studies conclude that vegetarians have a lower body mass index, and the interventional studies show the value of a vegetarian diet for weight loss. While some studies suggest that vegetarianism may be associated with orthorexia nervosa, the results regarding the association between vegetarianism and eating disorders are more heterogeneous and depend on the type of samples and dimensions studied. The heterogeneity of these findings is discussed in light of the methodological limitations of the studies to provide perspectives for future research.