An estimated 2.5% of the U.S. population is vegetarian. Soy milk, veggie burgers and other vegetarian foods are now much more easily found, not only in mainstream grocery stores, but at restaurants and fast food joints as well. People choose to adopt vegetarianism for an array of reasons, including concerns for the environment or animals, or for health, financial, ethical, religious or cultural reasons. Vegetarian diets can vary, but vegetarians generally don't eat meat, poultry or fish, and vegans also exclude dairy products and eggs. Vegetarianism has numerous research-backed health benefits, but is it a good strategy for weight loss?

In areas of the world where most of the population is vegetarian, there is a lower incidence of chronic diseases, such as heart disease, cancer, and diabetes--diseases all linked with obesity. A recent scientific review that looked at data from 87 clinical studies showed that the body weight of vegetarians is, on average, 3-20% lower than that of non-vegetarians. Does this mean becoming a vegetarian automatically translates into weight loss?

Not exactly. Most likely, it's the consumption of plenty of fruits and vegetables, and not necessarily the exclusion of meat, that makes vegetarians so healthy. Researchers attribute the lower body weight of vegetarians to a lower total calorie intake (as most vegetables are lower in calories than meats) and a high-fiber intake, which helps curb hunger. This does not mean you will lose weight by simply cutting out animal products, as you can still get too many calories from other foods. Researchers also acknowledge that vegetarians tend to have healthier lifestyle habits in general (such as getting ample exercise), and this contributes to maintaining a healthy weight.

With all of this research indicating that vegetarian diets promote health, one may wonder if there are any drawbacks. Vegetarian diets can fall short on protein, but this can easily be avoided by incorporating more beans, nuts, legumes, and soy foods (such as tofu) into your meals and snacks. Vegetarians are also at a higher risk for certain nutritional deficiencies, including vitamin B12, iron, calcium, zinc and omega-3 fatty acids.

According to the American Dietetic Association's position statement on vegetarian diets: "Appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence and for athletes."

The bottom line: You have to balance the calories you take in from food with the calories you expend (from a combination of calories used for basal metabolism and calories burned during physical activity). Any eating plan that causes you to take in more calories than your body needs will lead to weight gain, regardless of the types of foods you choose. So whether or not you opt to eat animal products, aim for a well-balanced diet and get plenty of physical activity. This will keep your waistline from expanding while providing countless health benefits in the process.