This document summarizes a talk given about issues related to food and food waste. It discusses how: 1) Rich countries like the UK have unsustainable food systems and diets, and waste a significant amount of food. 2) The global food system contributes substantially to greenhouse gas emissions, biodiversity loss, and other environmental problems. Changing many aspects of how food is produced, packaged, marketed and consumed will be needed to develop a sustainable system. 3) Making these changes will be very challenging given the complexity of the food system and entrenched interests, but awareness of the need for change is growing among governments, businesses and civil society groups.