Urban metabolism studies use different approaches to quantify urban food demand (Goldstein et al. 2016). They either use national per capita statistics scaled to the resident population or an input-output balance using trade statistics (Barles 2009, Niza et al. 2009; Rosado et al. 2014). The benefit of these approaches lies in the good availability of the required data and their easy operation. Their inconvenience lies in the approximate nature, considered insufficient, of the resulting food flows for studies interested in sustainability issues of urban food systems, such as urban foodprint or the relation to the supplying hinterland (Billen et al. 2012. Quantitative studies about e.g. cities’ or metropolitan areas’ degree of self-sufficiency in food supply (Tedesco et al. 2018) or linearity versus circularity of nutrient flows (Esculier et al. 2018) requires a detailed assessment of urban food consumption.

To overcome this limitation for urban food metabolism studies, we developed the notion of the eating population and the equivalent eater, anchored in the urban public services literature, to characterize and quantify the actual eating population of a city, including tourists and commuters, and its related food consumption. Its operationalization as developed so far combines multiple and different types of data from the field of tourism, transport and mobility and food intake available partly from databases of official statistics or national surveys. A web-based tool currently under development within the INRAE-funded project POPCORN aims to simplify the operation of quantification.
Our first empirical results show that the eating population and its related food consumption are equal or lower than comparable results calculated with the resident population, for the cities and periurban areas covered so far in our research. Future work includes analysis of more diverse urban or periurban areas according to different characteristics (embeddedness in metropolitan areas, isolated cities, tourist places etc.).

As a contribution to this conference, we suggest to share the concept, method and first empirical results of our research. We would moreover like to discuss with the participants experiences or expertise with respect to the following questions:
- Usefulness of the approach of population equivalent for non-food sectors (e.g. energy consumption) as it covers mobility, time of presence versus absence from the urban system
- Features of cities that influence the eating population, e.g. socio-economic status of the population, embeddedness in commutersheds etc.