Adopting a healthy vegetarian diet isn’t as simple as scraping meat off your plate and eating what’s left. You need to take extra steps to ensure you’re meeting your daily nutritional needs.
Vegetarian diet planning
A healthy vegetarian diet consists primarily of plant-based foods, such as fruits, vegetables, whole grains, legumes, nuts and seeds. Because the emphasis is on nonmeat food sources, a vegetarian diet generally contains less fat and cholesterol, and typically includes more fiber.
Vegetarians fall into groups defined by the types of animal-derived foods they eat:

Vegans eat only plant-based foods. They don’t eat foods from animals, including meat, poultry, fish, milk, eggs and cheese.
Lacto-vegetarians consume milk and milk products along with plant-based foods. They omit eggs as well as meat, fish and poultry.
Lacto-ovo vegetarians eat eggs, milk and milk products, such as cheese and yogurt, in addition to plant-based foods. They omit red meat, fish and poultry.
Flexitarians (semivegetarians) primarily follow a plant-based diet but occasionally eat small amounts of meat, poultry or fish.

To keep your vegetarian diet on track, you may find using a vegetarian food pyramid helpful. This pyramid outlines various food groups and food choices that, if eaten in the right quantities, form the foundation of a healthy vegetarian diet.
No matter what your age or situation, a well-planned vegetarian diet can meet your nutritional needs. Even children and teenagers can do well on a plant-based diet, as can older people, and pregnant or breast-feeding women. If you’re unsure whether a vegetarian diet is right for you, talk to your doctor or a registered dietitian.
Meatless products, such as tofu dogs, soy burgers, nut loaves or texturized vegetable protein, add variety to your vegetarian diet. These products, found in many grocery stores and health food markets, simulate the taste and texture of meat and usually have less fat and fewer calories. Many of the meatless products, such as tofu or tempeh, are made from soybeans.
If you follow a vegan diet, you may need to find alternatives for eggs and dairy products. Try these suggestions when meal planning or cooking:

Milk. Drink fortified soymilk, rice milk or almond milk in place of cow’s milk.
Butter. When sauteing, use olive oil, water, vegetable broth, wine or fat-free cooking spray instead of butter. In baked goods, use canola oil.
Cheese. Use soy cheese or nutritional yeast flakes, which are available in health food stores.
Eggs. In baked goods, try commercial egg replacers — a dry product made mostly of potato starch. Or you can use the following to replace one egg: 1/4 cup whipped tofu or 1 tablespoon milled flaxseed mixed with 3 tablespoons of water. For an egg-free omelet use tofu instead of eggs.

Ensuring adequate nutrition
The more restrictive a diet is, the more difficult it is to get all the nutrients your body needs. A vegan diet, for example, eliminates food sources of vitamin B-12, as well as milk products, which are a good source of calcium. Other nutrients, such as iron and zinc, are available in a meatless diet, but you need to make an extra effort to ensure they’re in yours.
Here are nutrients that may be deficient in a vegetarian diet and how you can get these nutrients from nonmeat sources:

Protein. Your body needs protein to maintain healthy skin, bones, muscles and organs. Vegetarians who eat eggs or dairy products have convenient sources of protein. Other sources of protein include soy products, meat substitutes, legumes, lentils, nuts, seeds and whole grains.
Calcium. This mineral helps build and maintain strong teeth and bones. Low-fat dairy foods and dark green vegetables, such as spinach, turnip and collard greens, kale, and broccoli, are good sources of calcium. Tofu enriched with calcium and fortified soy milk and fruit juices are other options.
Vitamin B-12. Your body needs vitamin B-12 to produce red blood cells and prevent anemia. This vitamin is found almost exclusively in animal products, including milk, eggs and cheese. Vegans can get vitamin B-12 from some enriched cereals, fortified soy products or by taking a supplement that contains this vitamin.
Iron. Like vitamin B-12, iron is a crucial component of red blood cells. Dried beans and peas, lentils, enriched cereals, whole-grain products, dark leafy green vegetables, and dried fruit are good sources of iron. To help your body absorb nonanimal sources of iron, eat foods rich in vitamin C — such as strawberries, citrus fruits, tomatoes, cabbage and broccoli — at the same time you consume iron-containing foods.
Zinc. This mineral is an essential component of many enzymes and plays a role in cell division and in the formation of proteins. Good sources of zinc include whole grains, soy products, nuts and wheat germ.

The key to a healthy vegetarian diet — or any diet for that matter — is to enjoy a wide variety of foods. Since no single food provides all of the nutrients that your body needs, eating a wide variety helps ensure that you get the necessary nutrients and other substances that promote good health.
Getting started
If you’re thinking of switching to a vegetarian diet but aren’t sure where to begin, start with menu planning.

Start with what you know. Make a list of meatless meals you already prepare regularly, such as spaghetti with tomato sauce or vegetable stir-fry.
Make meatless substitutions. Select meals that could easily become meat-free with a couple of substitutions. For example, you can make vegetarian chili by leaving out the ground beef and adding an extra can of black beans or soy crumbles. Or make fajitas using extra-firm tofu rather than chicken. You may be surprised to find that some dishes require only simple substitutions.
Experiment with new meal ideas. Buy or borrow vegetarian cookbooks. Scan the Internet for vegetarian menus or for tips about making meatless substitutions. Check out ethnic restaurants to sample new vegetarian cuisine. The more variety you bring to your vegetarian diet, the better the chance you’ll meet all your nutritional needs.