Orlistat is currently the only prescribed form of pharmacological management for obesity and functions by reducing the amount of fat absorbed from food eaten. Although frequently prescribed, there is marked variability in outcomes. A total of 10 participants’ experiences of gaining weight after taking orlistat were analysed using thematic analysis. Participants attributed their failed weight loss to mechanisms of the medication, emphasised a medical model of obesity with barriers to their weight loss and other weight-loss methods which had also failed. Overall, their weight gain was considered an inevitable part of their self-identity, reflecting their self-fulfilling prophecy of being a perpetual dieter.