This chapter explores the environmental impacts of different diets, providing an overview of implications related to climate change and greenhouse gas (GHG) emissions, land and water use, and biodiversity loss. Original estimates are included for the global warming potential of GHGs associated with two selected foods (beef and wheat) on a 20-year horizon, consistent with methane’s life span in the earth’s atmosphere, as well as the population that the planet can support on a plant-based diet. Irrespective of the type of environmental impact considered, the consumption of animal-based products, and meat in particular, is associated with a heavier ecological footprint that exceeds the capacity of the planet and its ability to feed the global population. A switch to vegetarian options can significantly ameliorate the ability of the earth’s biosphere and atmosphere to provide habitat for all living species.