Every diet has an impact on an individual’s health status, the environment, as well as on social concerns. A growing number of meals are consumed in the out-of-home catering sector, in which a systematic sustainability assessment is not part of common practice. In order to close this gap, an instrument was developed as part of the NAHGAST project. After more than one year of using the NAHGAST online tool, it needs to be assessed what positive environmental influences can be realized by using the tool. For this reason, this article deals with the question of whether an online tool can enable stakeholders from the out-of-home consumption sector to revise their meals with regard to aspects of a sustainable diet. In addition, it will be answered how precise recipe revisions of the most popular lunchtime meals influence the material footprint as well as the carbon footprint. In conclusion, an online tool can illustrate individual sustainability paths for stakeholders in the out-of-home consumption sector and enables an independent recipe revision for already existing meals. The results show that even slight changes in recipes could lead to savings of up to a third in carbon footprint as well as in material footprint. In relation to the out-of-home consumption sector, this results in the potential for substantial multiplication effects that will pave the way for the dissemination of sustainable nutrition.

Sustainability as a guiding idea for societal and economic development causes a growing need for reliable sustainability assessments (SAs). In response, a plethora of increasingly sophisticated, standardizAed, and specialized approaches have emerged. However, little attention has been paid to how applications of SAs in different contexts navigate the challenges of selecting and customizing SA approaches for their research purposes. This paper provides an exploration of the context-specific conditions of SA through a case study of three research projects. Each case study explores the different approaches, methodologies, as well as difficulties and similarities that researchers face in “doing” SA based on the research question “What are common challenges that researchers are facing in using SA approaches?” Our case study comparison follows a most different approach for covering a wide range of SA applications and is structured along with three key challenges of doing SA: (i) Deliberation, learning and assessment; (ii) normative assessment principles; (iii) feasibility, especially regarding data quality/availability. Above all, the comparative case study underlines the role and importance of reflexivity and context: We argue that a more explicit and transparent discussion of these challenges could contribute to greater awareness, and thus, to improving the ability of researchers to transparently modify and customize generic SA methodologies to their research contexts. Our findings can help researchers to more critically appraise the differences between SA approaches, as well as their normative assumptions, and guide them to assemble their SA methodology in a reflexive and case-sensitive way.