The primary aim of this study is to investigate the convergent and discriminant validity of injunctive and descriptive norms in forming subjective norms. It also examines the influence of subjective norms, encompassing normative beliefs (injunctive and descriptive norms) and the motivation to comply, on the intention to consume Amino 2000 supplements among fitness enthusiasts in Indonesia. This research, employing a mixed-method approach combining qualitative and quantitative analyses, was conducted in four major Indonesian cities: Jakarta, Bandung, Surabaya, and Semarang. The study sample comprised 393 fitness aficionados from five distinct fitness centers across the region. The findings support four hypotheses posited by the researcher. Overall, subjective norms, including normative beliefs (injunctive and descriptive norms) and motivation to comply, more effectively predict and explain the intention of fitness mania to consume Amino 2000 supplements, compared to either injunctive norms, descriptive norms, a combination of both, or the normative beliefs formed by these norms, along with the constituent motivation to comply.

Keywords: Subjective norms, Injunctive norms, Descriptive norms, Mixed method, Fitness mania