The environmental and health impacts of diets and dietary change in 5,500 cities worldwide

The majority of the world’s population live in cities, making urban food environments an important driver of global diets and their associated health and environmental impacts. However, only a few dietary and food-system assessments have been conducted at the city level, often with important shortcomings which limit consistent policy planning. Existing studies cover only a few cities and mostly large ones, leaving many smaller cities without estimates. Further, most simply scaled national estimates of food intake – either from food balances or surveys – to city populations. We combined dietary data for urban residences by age and sex, gridded age and sex structures from WorldPop, and urban settlement polygons from the Global Urban Polygons and Points Dataset (GUPPD), to estimate the dietary intake in 5,500 cities with populations over 100 thousand inhabitants. Our estimates indicate that diets in most cities contained greater amounts of foods compared to a country’s average intake in 2020. As a result, cities in most regions were responsible for a larger share of food-related environmental resource use and pollution compared to their share of population. This was mostly driven by increased intake of animal source foods in cities included in our impact assessment. Cities were also responsible for a large share of diet-related health burden and an outsized share of health-related costs, in line with the generally higher cost levels observed in cities. Dietary changes to healthier and more sustainable diets could substantially reduce the environmental, health, and cost impacts associated with city diets, but are dependent on consistent policy approaches and support.