According to a popular saying, we are what we eat. And if you look at the human diet, it is clear that we—and are food—are environmentally destructive. Adopting more plant-based diets—veganism, vegetarianism, pescatarianism, the Mediterranean diet, or even just a diet that adheres to common health recommendations—could offer a win-win for both human and environmental health. According to recent research, such dietary changes could reduce global mortality by up to 10% and reduce food-related greenhouse gas emissions by up to 70% relative to a 2050 reference scenario. The economic benefits would be in the trillions of dollars. Realizing such gains will require major changes at all levels of the modern industrial food system, but if we want thriving lives on a livable planet, then we need to whet our appetite for social and political change.