This report from the EAT Forum examines current food consumption patterns and finds that most national dietary guidelines do not integrate both health and environmental sustainability. It finds that halving food-related greenhouse gas emissions in G20 countries by 2050 would contribute towards equitably feeding 10 billion people within planetary boundaries.
The modelling used in the report is based on the paper The healthiness and sustainability of national and global food based dietary guidelines: modelling study, summarised by the FCRN here.
Read the full report, Diets for a Better Future: Rebooting and Reimagining Healthy and Sustainable Food Systems in the G20, here. See also the Foodsource chapter What is a healthy sustainable eating pattern?