► The food system contributes substantially to global greenhouse gas emissions. ► Technological mitigation approaches, while necessary, may not be sufficient. ► Dietary shift away from meat and dairy products is also needed. ► This could yield health benefits for developed world consumers. ► But it would pose major nutritional challenges for developing countries. ► A nutrition oriented agriculture that sits within environmental limits is needed. This paper reviews estimates of food related greenhouse gas (GHG) emissions at the global, regional and national levels, highlighting both GHG-intensive stages in the food chain, and GHG-intensive food types. It examines approaches that have been proposed for mitigating emissions at each stage in the chain and looks at how these sit within wider discussions of sustainability. It finds that efficiency-focused technological measures, while important, may not only be insufficient in reducing GHGs to the level required but may also give rise to other environmental and ethical concerns. It gives evidence showing that in addition to technological mitigation it will also be necessary to shift patterns of consumption, and in particular away from diets rich in GHG-intensive meat and dairy foods. This will be necessary not just in the developed but also, in the longer term, in the developing world. This move, while potentially beneficial for food secure, wealthier populations, raises potentially serious nutritional questions for the world’s poorest. A priority for decision makers is to develop policies that explicitly seek to integrate agricultural, environmental and nutritional objectives.