## 1 Introduction  
The sustainability of the food system is one of the main challenges facing humanity [1; 2]. The agri-food system needs to transition toward a more balanced system from an economic, social, and environmental point of view [3; 4]. The Green Deal 2019-2024 [5] and the Farm to Fork strategy [6] address this challenge at the European level.  
The perceptions of the population about the existing food systems and their willingness to change their food habits are key in this transition. [PERSON] and [PERSON] (2005) [7] stated that sustainability is about sustainable consumption rather than sustainable production. However, consumption can compromise sustainability [8].  
Achieving changes in individuals' consumption patterns and reductions in the volumes of consumption have been referred to as \"strong sustainable consumption\" or \"deep green consumerism\". Consumers not only seek to purchase eco-friendly alternatives but, more importantly, they seek to reduce their overall level of consumption [9; 10]. On the other hand, \"weak sustainable consumption\" or \"shallow green consumerism\" only entailsan improvement in consumption efficiency and does not necessarily change their overall level of consumption [9; 10].  
Young people are a special demographic group to consider in the transition toward sustainable food consumption (SFC) [11; 12], and public universities are an environment in which people engage with the food system and make decisions about consuming food. Some studies have focused on young consumers and food habits transition [13; 14; 15]. However, more information is necessary to understand this key population and to support their transition toward more sustainable food habits. The perceptions and contexts of these young consumers are different in different regions; this study aims to fill information gaps in the relevant literature regarding young people from Spain.  
Additionally, public universities are demanding information to plan new sustainable food services. This paper focuses on filling information gaps to support the role of green public procurement and public universities in the transition toward a sustainable food system (SFS). According to FAO [16], an SFS is profitable throughout (economic sustainability), has broad benefits for society (social sustainability), and has a positive or neutral impact on the natural environment (environmental sustainability).  
This paper aims to identify and characterize the perceptions of young people aged 18 to 35 [17] and in university to support strategies to promote the transition to a more sustainable and healthy food model.  
Spanish public universities are committed to the notion of sustainability [18], but ensuring the sustainability of their food services is a big challenge for them. This paper focuses on the region of Madrid (RM), the region with the largest number of university students in Spain (17%) [19]. The research questions we sought to find answers for are listed below:  
* RQ1. What are the perceptions of university students on food sustainability?
* RQ2. What eating habits would they be willing to change?
* RQ3. What kind of profiles can be identified among young university students about sustainable food systems?