While there are different harms that are related to sport/exercise (hooliganism, gambling, drug use, violence, etc.), in this chapter we are particularly interested in exploring the ‘subjective harms’ and ‘embedded harms’ associated with the exercise regime known as CrossFit, with specific attention to the use of performance and image enhancing drugs (PIEDs) and dietary supplements within this milieu. Drawing on the deviant leisure perspective, the chapter explores the possible ways in which CrossFitters may ‘self-harm’ in their conformity to social norms and values and specifically the cultural injunction to either perform or be aesthetically appealing and, more importantly, how these harms may be mitigated, meditated or exacerbated by a CrossFit leisure identity. The main purpose of this chapter is to (1) empirically investigate the reported prevalence of supplements and PIEDs in CrossFit within the UK, (2) examine the relationship between CrossFit and (un)healthy behaviours and practices more generally and (3) situate our findings within the broader theoretical lens of deviant leisure.