For many people, being a vegetarian is a logical outgrowth of “thinking green.” A meat-based food system requires more energy, land, and water resources than a plant-based food system.  This may suggest that the plant-based diet is more sustainable than the average meat-based diet.  By avoiding animal flesh, vegetarians hope to look after their own health and that of the planet at the same time.  Broadly speaking, vegetarians eat beans, grains, and fruits and vegetables and do not eat red meat, poultry, seafood, or other animal flesh.  Some vegetarians, known as Lacto vegetarians, will eat dairy products.  Others, known as Lacto-ovo vegetarians, will eat dairy products and eggs.  A vegan diet is the most restrictive vegetarian diet—vegans do not eat dairy, eggs, or other animal products, and some do not eat honey or yeast.

Vegetarian diets have many benefits.  Well-balanced eating plans can lower the risk of several chronic conditions, including heart disease, diabetes, and obesity.  They also help to promote sustainable agriculture.  However, if a vegetarian does not vary his or her food choices, the diet may be insufficient in calcium, iron, omega-3 fatty acids, zinc, and vitamin B12.  Also, if people who follow these diets do not plan out their meals, they may gravitate toward foods high in fats