In France, collective catering is a sector under pressure due to, inter alia, controlled meal prices, strict health regulations, and new needs and consumption patterns (such as the development of teleworking and food preferences). In addition to these constraints, there are new regulations and directives for the development of a sustainable food supply, notably under the Egalim law. This encourages, and sometimes even compels, changes within these collective catering organizations. Our aim is to study how managers are steering these changes. In this article we propose a multidisciplinary approach that combines management science and ergonomics to identify the work transformations introduced by middle managers, and their framework for managing change in private catering organizations seeking to offer more sustainable meals. In order to identify key situations in middle managers’ work that require further investigation, we adopt a longitudinal and systemic approach to organizational change and highlight some markers of the managerial activity (organizational processes and management tools). This method is structured around four forms of representation: (1) a timeline of change; (2)a narrative focusing on a given lever of change in relation to sustainability issues; (3) a process flow chart; and (4) an identity card for management tools. We illustrate its use with the case of the introduction of a daily vegetarian dish in a collective catering organization. The multiplication and articulation of these representations allow us to identify and to characterize the nature and extent of the changes while providing a more systemic understanding. This serves as a support to discuss with the middle managers their activity related to the development of a sustainable food supply