For lumia: it can be quite difficult to keep down weight without exercise on a veggie/pasta diet. Mostly because that pretty much translates to carb diet. That doesn't mean you have to eat meat, but do ensure you're getting plenty of protein from beans, nuts and seeds. Also make sure your veggies cover a large variety. And try to stick with whole wheat/grain pastas whenever possible. And be careful with the use of oils to flavor (including salad dressings)

Many people think eating salads and going vegan is 'healthier' or will translate to weight loss, but rarely is that the case in fact the opposite is generally more true. The number one issue is to pull off a vegetarian diet one has to basically be a grazer, that is not allowing more than two hours pass without eating. When ones diet is higher in carbohydrates it quickly burns through them, by not replenishing them you're telling your body it is in 'starvation' mode. Which causes it to store them any way they can (weight gain).

Also there's the difficult task of finding veggies and fruits with similar amino acids to red meat (such acids actually help the body build muscle and burn fat) I beleive its gourds that can mimick meats in that, but not 100% sure.

However the number one thing is to ensure you are still getting plenty of protein without eating meat. A body with insufficient protein will turn to mush, it's what fuels and builds muscles, without enough even if you were an Olympic competitor last year your body would quickly breakdown making weight loss impossible.