In this article, I describe the processes through which patients diagnosed with 'morbid obesity' become active subjects through undergoing obesity surgery and an empowerment lifestyle programme in a Dutch obesity clinic. Following work in actor-network theory and material semiotics that complicates the distinction between active and passive subjects, I trace how agency is configured and re-distributed throughout the treatment trajectory. In the clinic's elaborate care assemblage - consisting of dieticians, exercise coaches and psychologists - the person is not only actively involved in his/her own change, the subject of intervention is the self as 'actor': his/her material constitution, inclinations and feelings. The empirical examples reveal that a self becomes capable of self-care only after a costly and laborious conditioning through which patients are completely transformed. In this work, the changed body, implying a new, potentially disruptive reality that patients must learn to cope with, is pivotal to what the patient can do and become. Rather than striving to be disembodied, self-contained liberal subjects that make sensible decisions for their body, patients become empowered through submission and attachment and by arranging support.