Not ideal being a vegetarian when trying to hold on to/gain lean mass (derived from protein aka COMPLETE amino acid pools). Just stating what you'll come to realize. Soy is a weak choice, milk sucks, leaving you w/eggs. Protein shakes are fine, but if you don't drink milk, I suspect you won't drink whey. In any event, liquid pales in comparison to real food which you need for satiety, nutrients, and metabolism purposes.
~SC~