eating a vegetarian diet has nothing to do with weightloss. or rather it has about as much to do with weightloss as what color shirt you decided to wear today.
if you really want to break out of a food rut, you could try switching to all veg meals. or you could simply head to the library, get a vegetarian cookbook and start trying out some of the recipes. or you could check out fatfreevegan.com
, or vegweb.com
and incorporate some of those recipes. you don't have to do it all at once, you can just try one or two new meals a week and see how you like it. if it works, great, keep going. if it's not quite to your tastes, head back to the library or any recipe site on the web and keep trying new things until you feel like you are out of your rut.