Climate change is threatening future global food and nutrition security. Limiting the increase in global temperature to 1·5 °C set out in The Paris Agreement (2015) while achieving nutrient security means overhauling the current food system to create one that can deliver healthy and sustainable diets. To attain this, it is critical to understand the implications for nutrition of actions to mitigate climate change as well as the impacts of climate change on food production and the nutrient composition of foods. It is widely recognised that livestock production has a much greater environmental burden than crop production, and therefore advice is to reduce meat consumption. This has triggered concern in some sectors about a lack of protein in diets, which hence is driving efforts to find protein replacements. However, in most high- and middle-income countries, protein intakes far exceed dietary requirements and it would even if all meat were removed from diets. Reduction in micronutrients should be given more attention when reducing meat. Simply eating less meat does not guarantee healthier or more sustainable diets. Climate change will also affect the type, amount and nutrient quality of food that can be produced. Studies have shown that increased temperature and elevated CO2 levels can reduce the nutrient density of some staple crops, which is of particular concern in low-income countries. Nutrition from a climate change perspective means considering the potential consequences of any climate action on food and nutrition security. In this paper, we discuss these issues from an interdisciplinary perspective.