My buddy pointed out a thing we all learned in Biology: that each step up the food chain is only a 10%(at best) transfer of energy. Therefore, it if you eat 1000 calories of meat, it took 10,000 calories of grains and grasses to make that meat.
So, let's just say it would take an acre of plants to feed you for a year, it would take 10 acres of plants to feed the meat if you ate only meat, instead. Now, assuming you eat a mixture of plants and meat, it could be assumed that you might need 3-5 acres to feed yourself, so by eating only plant products, you would be reducing the amount of land you would need to displace to 1/3 -1/5th of the land required if you ate meat.
Considering that, you would also be using 1/3 of the time farming, 1/3 of the soil amendments, 1/3 of the processing, 1/3 of material shipping costs, 1/3 of the storage costs, 1/3 of the water, so-on, and so forth. The total saved by eating only plant-foods would be immense.
I like my meat, as well, but after going over the maths, I think I might try cutting down on my meat and animal products as well. This includes wool and leather. ...I mean, I could justify hunting, because we've killed off predators in some areas, and we need to take that place in some ecosystems, but shoot...