Around one third of the weight of food produced for human consumption is lost or wasted, and around a third of crop calories are lost to the food system during livestock production. Meanwhile, the global food system causes significant environmental impacts and around 800 million people are undernourished. This building block examines the following aspects of food loss and waste: mainstream definitions and alternative understandings, global statistics, and ‘hierarchies’ for prevention and treatment. Last update: 25 March, 2019 https://www.doi.org/10.56661/f98ed9f6