I still think you have to watch your fat and calories while on a vegetarian diet. If you are not careful you may end up loading up on carbs and dairy products. When I first started looking for vegetarian recipes to make for my dad I found that there were a lot that consisted of pasta, rice and/or cheese. But I am now able to find ones that are lower in calories and fat. there are also a whole slew of vegetarian products on the market now which means there is a lot more choice out there than there used to be
I think if you switch to lower fat cheese or soy cheese and go for whole grains and whole wheat pasta it may help. The important thing is to make sure you are eating a balanced diet and getting proper amounts of protein, iron and vitamins from other sources besides meat.
Including exercise in your plan is just as important as what you eat.
For myself I try to eat as many fresh foods as possible and prepare my own lunches and meals. I am not a big fan of processed food so I don't buy prepackaged foods or frozen dinners very often. I also try to buy organic foods when I can find them and if they are affordable.
I am also trying to incoporate soy into my life but I am not a huge fan of it so for the moment I am sticking to drinking chocolate soy milk -which I find quite tasty and chocolate soy pudding which is not bad.
Try to read to read the labels of any vegetarian products to check for the fat content if you are concerned about the amount of fat in your diet and use "good" oils like olive oil when cooking.