Vegetarian diets are often rich in dietary fiber. The Harvard School of Public Health describes fiber as an indigestible type of carbohydrate that adds bulk weight to the stool, causing regular bowel movements. Fiber also provides many health benefits such as lowering diabetes and diverticulitis risks. According to the Harvard School of Public Health, whole grains, beans, nuts, seeds and lentils are all high in fiber. Fruits and vegetables contain fiber too, while meat and dairy contain none. Fiber in the vegetarian diet helps to regulate digestion so that things don’t move too fast or too through the body.