I suspect you've got your tongue in cheek, but I actually believe this to be true. The amount of vegetables, legumes, grains, and fruit required to eat to satiety is enormous. Eating a low carb, primarily carnivorous diet, I make fewer trips to the grocery store, fewer trucks have to bring in produce, my fridge is opened fewer times, less water is used to wash my food, etc. etc. Until I see a study taking all the never considered factors into account, I will assume that the advice that vegetarianism will save the planet is as fake as the food pyramid.