Sustainable diets had become an increasingly important topic. This concept considers current and future generations and good conditions of life for all. This multidimensional definition makes its application challenging for consumers in their food choices. In this context, our study aimed to identify the product properties used by French consumers while making sustainable food choices and to explore some facilitators of a transition towards more sustainable choices. A total of 253 French consumers participated in an online food choice intention task that was designed to mimic an online grocery store. A between-group experimental design was used to compare participants' food-choice intentions in the two conditions induced by two different scenarios. In the "sustainable" condition, the scenario referred to a motivation for sustainability, whereas in the "control" condition, it referred to daily food choices. The food categories (fruits, vegetables, meat, fish, etc.) and characteristics (production, processing, packaging and additional information) of the products chosen by the participants were compared between the two conditions. The relative influence of the participants' characteristics and motivations induced by the scenario on food choice intentions was also analysed. The participants' sustainable choices relied mainly on sustainability characteristics (local origin of products, packaging material, fair trade, degree of processing and nutritional quality) rather than on a modification of food categories. Furthermore, the participants exposed to the "sustainable" scenario considered the task more difficult than did the participants in the control group. Finally, the effectiveness of external motivation was moderated by personal characteristics, such as gender and diet.