Ephedrine use in sport is a common practice among men. Less well-understood is men’s use of ephedrine as a slimming aid. Arguably fuelled by the ‘war on obesity’ and the drive for muscularity the internet has become awash with claims presenting ephedrine as safe. The use of this psychoactive substance can have acute health implications such as tachycardia, arrhythmias and cardiovascular disease. Given the tension between health risk and ephedrine-induced weight loss, how men justify their use of ephedrine becomes an important question. In particular, we wished to analyse how male users talked to others about ephedrine in discussions linked to an online version of a popular men’s magazine. Because we were particularly interested in how men accounted for their ephedrine use, we used discourse analysis to examine their posts. In analysing the data, we noted that a “community of practice” was constructed online categorising legitimate (and barred) users, emphasising the benefits of ephedrine, and downplaying health-defeating side effects. Our analysis has clear implications for engaging men who use ephedrine in health promotion interventions.