The one cautionary note about vegetarianism is that simply eliminating meat does not automatically produce a healthy diet. You still need to pay attention to the quality and quantity of what you eat. A healthy vegetarian diet focuses on whole foods like fruits, vegetables, beans, legumes, and whole unprocessed grains, and limits processed and refined sugars and empty calories. There is no shortage of vegetarian and vegan junk food out there. Remember, the root word of vegetarian is "veg" not "junk." Here are 2 pyramids here from VegSource to help you out.
VEGETARIAN FOOD PYRAMID
VEGAN FOOD PYRAMID