In several countries, nutritional labelling is one of the tools being considered or already implemented by public authorities to attempt to modify consumer behaviour in the face of the health impacts of imbalanced diets. The results summarised here attempt to identify the interests and limits of these labelling approaches and to assess the existing or potential effects both on the demand side (modification of consumer choices) and on food supply (modification of corporate strategies). Descriptive labelling would seem to have a more modest, diffuse and longer-term impact on consumers who prefer short-term taste properties to nutritional impacts. Prescriptive labelling identifying “nutritionally healthy” products and products “to be limited” could have a more pronounced impact by helping reorientate consumer behaviour. However, its impact on the supply side depends on the practical terms of implementation; there is a risk of seeing the emergence of balances between supply and demand in which the changes in the former are cancelled out by the latter, without any significant nutritional improvement.