The analysis of the food value chains for all the food consumed in metropolitan France represents a considerable scientific challenge, due to its scope and the complexity of the production, processing and distribution systems, on a globalized market. Therefore, the calculations needed to rely on a large amount of statistical data, supplemented by hypotheses and expert statements. Approximations and simplifications had to be made and are documented in the methodological report. The construction of hypotheses has always been carried out in the most "systematic" way possible in order to avoid bias, and by concentrating efforts on the most impactful structuring parameters. Thus, a particular effort was made on the agricultural stage, which represents the greatest impact phase for a majority of products, while the phases of transformation, logistics, packaging and use have been simplified.