Will being Veggie help one to stay slim?

Not necessarily. Even though being a vegetarian can have tremendous health benefits, it's not always the road to "slim and sexy". I have a friend who's been a vegetarian for most of his life and he's overweight. He eats a lot of dairy including ice cream and he also eats lots of pastries and cakes. Just because something is meatless doesn't mean it's going to help you lose weight or maintain a healthy weight. Whether someone is a vegetarian or not, they will still need to watch their intake of calories and fat grams if they wish to stay/become slim.

Well...not necessarily. But eating a diet that is predominately made up of plant-based foods likely is. You may ask what the difference is...well...I can make a vegetarian brownie full of sugar and fat. It is, however, no better for my health (or my waistline) than a non-veg one.

I agree with the first respondent, being a vegetarian or vegan doesn't guarantee that you will be slim. However, vegetarians tend to be slim because many of them are vegetarian for health reasons. But, I have seen a lot of "vegetarian" or "vegan" foods that are high in fat and sodium, both of which will make you gain weight and hold on to excess water. It all has to do with metabolism and calories in/calories out.