Vegetarian is not necessarily healthier and may not lead to weight loss.
Not all vegetarians are skinny or healthy. It is important to understand that vegan or vegetarian diets are not all the same. Vegetarians often eliminate meat for religious or health reasons. Many will continue to eat processed foods. I have many friends who replaced meat with beans but continued to eat junk food. They tout the benefits of a plant-based diet but fail to understand the ramifications of each decision they make.
While vegetarians and vegans consume fewer calories and less fat on average than those that eat meat. This fact may not tell all of the stories. One study looked at this very issue. It was published in The Journal of the Academy of Nutrition and Dietetics. It is a cross-sectional study of 71,751 subjects with a mean age of 59 years from the Adventist Health Study 2. The study looked at the dietary patterns of nonvegetarians, semi-vegetarians, pesco vegetarians, lacto-ovo vegetarians, and strict vegetarians. Calorie intake was similar among dietary patterns at close to 2,000 kcal/day, but the semi-vegetarians had an intake of 1,707 kcal/day. The results revealed that the mean body mass index was highest in nonvegetarians (mean=28.7) and lowest in strict vegetarians (mean=24.0).
Going vegetarian solely for weight loss could backfire. You must be extra vigilant with a vegan diet to get the nutrients you need. When you avoid meat and dairy, it is easy to lack essential amino acids, fatty acids, nutrients, and vitamins. Many vegans may also find themselves reaching for more processed foods like vegan cookies, chips, desserts or snacks with such a restricted diet which could pack on the pounds. To get enough protein, many vegetarians will reach for foods such as beans, legumes, eggs, nuts, seeds, low-fat dairy, and soy products. These are high in protein and often have high in fat and calorie-dense. Weight loss is still dependent on the number of calories you eat and burn and no change in the type of food you consume will change that fact.
The bottom line: Research shows that people who follow a vegetarian eating plan tend to eat fewer calories and less fat than non-vegetarians. Some research has even found that vegetarian-style eating patterns are associated with lower levels of obesity, lower blood pressure, and a reduced risk of heart disease. Vegetarians also tend to have lower body mass index scores than people with other eating plans. But vegetarians can make poor food choices that can cause weight gain. You still must make sound decisions to avoid weight gain.