Formally, the concept of sustainable consumption and production was born at the 1992 World Summit on Sustainable Development, seeking to address sustainability challenges ^[1][35] and linking consumption with sustainable development ^[2][36]. In 1994, the Norwegian Ministry of the Environment provided the most cited definition (Table 1): sustainable consumption (SC) implies the use of services and products that meet both needs and improvement of the quality of life while reducing environmental impact so as not to endanger the well-being of future generations ^{[1][3][4][5][6][7]}[3,6,15,35,37,38].

In the vision of ^[8][39], the conceptualization of SC can be seen as a part of sustainable development, as the previously mentioned definition, or as a term that brings together key characteristics revolving around the satisfaction of needs, improvement of quality of life, resource efficiency, minimization of waste, the extension of shelf life [9] or the need for changes in consumption patterns ^{[9][10][11][12]}[9,12,17,20]. In other words, it brings together concepts linked to environmentally friendly behavior in the context of the acquisition of products and services ^[13][40]. According to ^[14][41], SC should no longer mean voluntary abstention from consumption choices (created in the linear paradigm) but the ability to maintain or improve a high quality of life despite the lower resource availability.

Despite the above-mentioned conceptualizations, there are criticisms due to the conceptual vagueness of SC or sustainability ^[11][15][17,42]. It is said that there is no generalized definition widely accepted by the scientific community ^{[5][11][12][16][17][18]}[11,15,16,17,18,20]. The obstacles that prevent consensus are rooted in its conceptual complexity and the nature of its application. Some of these may be: SC subjectivity that may have a different meaning for each person, i.e., it may involve buying organic food, recycling, opting for environmentally friendly means of transport or other eco-friendly behaviors ^[4][6], the heterogeneity of parallel research streams (responsible—ethical—green consumption, etc.) that generate both greater breadth and vagueness ^[16][11], the dichotomy present in its name (sustainability vs. consumption) and the multidisciplinary approach of its base terms ^[11][17], the current state of the market that encourages unsustainable consumption patterns and consumerism ^[10][16][11,12], the involvement of consumers and their systemic alterations as actors of social change interacting with the environment ^[10][19][12,43], the conjunction of individuals and entities of different levels in decision-making ^[20][44], or the need to consider alterations caused by disruptive agents in future consumption patterns ^[17][16]. In light of everything that has been said, it becomes clear that sustainable consumption can have different conceptualizations (Table 2), depending in many cases on the perceptions of the authors, the purpose of the study, and the contexts in which the phenomenon occurs, among others.

Both the conceptual complexity and breadth of SC are given from the links with related terms, such as responsible consumption, ethical consumption, anti-consumption, mindful consumption ^[11][17], or green consumption ^[21][45], highlighting the differences between these concepts. For example, according to ^[25][48], the difference between green consumption and ethical consumption is that the former focuses only on the environmental factor, while the latter integrates social factors. In another case, the difference between anti-consumption and mindful consumption is also observed. The former is the voluntary choice to avoid waste due to a thrifty (but not environmentally conscious) personality, deriving pleasure in not spending, or the desire to lead a simple life considering non-materialistic factors, although it may integrate an environmental concern ^[26][49], while the latter invites reflection in consumption, replacing hedonic values and prioritizing benevolent behaviors that reduce impulsive, compulsive or addictive purchases ^[11][17]. Similarly, SC is based on the 3Rs [reduce, reuse, and recycle] ^[4][9][6,9], being a guide that makes up the shared action of circular behavior ^[27][50] while finding conceptual similarities in its environmental nature with green consumption ^[21][25][45,48].

It should be noted that sustainable consumption and production have two compounds, and there are discrepancies as to how they should be approached. Ref. ^[28][51] points out that sustainable production is subject to SC, although he also states that both terms can be approached jointly or separately. On the other hand, Ref. ^[22][46] considers that SC depends on sustainable production, intuiting that products should be conceived under the circular paradigm so that both concepts should be approached as a whole. From another perspective, sustainable consumption and production are considered to interact with each other, where the consumer has a vital role in the former and little direct influence on production ^[12][20], which actively involves business and government.

The fact is that regardless of how it is approached, SC is quite broad since a large number of factors influence how it performs. Omitting the already influential demographic characteristics, aspects, such as religion ^[29][30][52,53], parental environmental values and family upbringing ^[31][54], culture [3], corporate irresponsibility ^[32][55], consumer associations ^[33][56], informed consumer and information availability ^[7][38], or the green consumer value-action/intention-behavior gap ^[23][34][35][47,57,58], to mention a few, are aspects that add layers of complexity to a term that is already difficult to define.

At a recent juncture, the COVID-19 pandemic has brought about changes in consumers, and economic problems. It is argued that the pandemic prompted changes in sustainable behavior, generating greater environmental awareness subject to sociodemographic characteristics ^[36][19], although, by itself, it does not appear to have the potential to change current consumption paradigms ^[12][20]. Despite having tentatively generated changes in favor of SC, such as the reduction in purchases of “frivolous” products ^[37][21], irresponsible behaviors linked to panic buying and unnecessary accumulation of products have occurred ^[5][12][15,20]; however, such attitudes are related to a natural reflex of human beings in a crisis. From the perspective of ^[24][22], the problems caused by the pandemic have led to impulsive and hasty purchases linked to the excessive use of credit cards, going totally against SC.

In essence, CE focuses on the extension of the shelf life of a product after its first life cycle ^[38][59], has a disruptive capacity that integrates concepts related to the interests of SC ^[11][16][11,17], having an impact ^[16][22][11,46] on the three main actors (consumers, governments, and corporations) that influence sustainability in consumption and production issues ^[39][60], which implies its capacity to generate socio-environmental changes in both the private and public sectors ^[16][11]. For all these reasons, its capacity to sustain and accelerate the development of sustainable consumption and production ^[40][41][42][61,62,63] is denoted, highlighting at the same time how it reliably integrates the paradigm of economic growth without undermining environmental well-being ^[43][64], which implicitly includes a cross-sectional vision that not only benefits SDG 12 but also several others ^[42][44][63,65].

The literature on CE tends to focus on the private sector, emphasizing sustainable business models while neglecting the necessary changes in the consumer to accept such scenarios ^[45][66]. It should be kept in mind that consumers perform a fundamental role in both the adoption of CE ^[2][16][11,36] and SC ^[10][12][19][12,20,43], being both concepts linked by the implications of the former, which demands an abrupt change in consumption values, patterns, and relationships ^[45][66], and encompass the idea of resource optimization, low-emission production, product efficiency, and gradual transition to green consumption ^[22][46].

Although various sustainable development practitioners focus on reducing the use of virgin materials at the production level, changes in this area are slow ^[46][67]. Given this, the consumer is key to achieving and accelerating the shift from a linear to a circular economy ^[47][68]. Its approval is a significant generator of change for current organizations ^[2][36], pointing out how the idea of generating changes at the behavioral level would allow for reducing the paradigm of “consume and throw,”, i.e., through the conception of multiple ownership of products, a closed loop is created that maximizes the use of resources while reducing waste ^[46][67]. According to the research by ^[48][69], consumers have a fundamental role that they do not usually perform, as they do not have a clear understanding of what CE is and how it allows for raising awareness and contributing to sustainable consumption and production. Ref. ^[47][68] add that citizens are becoming increasingly aware of their responsibility in consumption cycles, although the latter recognize their lack of understanding of CE.

In the context of CE, consumer behavior implicitly encompasses aspects of SC ^[27][50], and consumer intervention can be reflected in the basic concept of the 3Rs ^[4][6] and its variants ^[27][50]. In other words, the consumer has a sustainable behavior when repairing, extending the shelf life of the product even considering the implicit design limitations ^[49][70], how difficult it is to allocate time to repair, and how easy it is to purchase a new product online ^[50][71]; recycling, sending products to a treatment process so that their materials serve as raw material for new materials or products, contemplating the differences in product categories and the type of recycling of these ^[51][72]; rethinking/reusing, considering the financial and social benefits of renting or buying second-hand products ^[21][52][53][45,73,74]; refurbishing a product, understood as improving the functional performance of an item (e.g., laptop), to keep it updated ^[54][75]; or remanufacturing, which involves the producer restores the product preserving its original function and added value ^[55][76]. Ref. ^[27][50] expands on this by expressing how the 9Rs framework interacts with CE (Table 3).