You do know that eating non-animal products is a lot less resource-intensive than eating meat? I mean, 90% of meat eaten comes from some sort of animal that was fed some sort of feed, which again in most cases had to be grown beforehand. Instead of the feed, grain for direct human consumption could be grown instead, a lot more "effectively", if you measure by energy/calory for example.
Not even going to start with what's wrong about saying that everything that's not meat is "only one source of food", as if hundreds upon hundreds of different grains, vegetables, fruits, algae, and whatever else is just one single homologous blob.