The availability of wearable devices recently boosted the popularity of self-tracking technologies. Self-trackers are involved in a complex process of knowledge development, but this cannot be achieved without knowing the body. However, self-tracking devices seem to embrace an abstract and scattered conception of the body, based on unrelated numbers, graphs, and depictions, which may not be integrated into a coherent body image. This may turn into biases and distortions of how we look at our bodies, worsening, rather than improving, our self-knowledge. In this chapter we explore the ways through which the progressive “quantification” introduced by self-tracking technologies is affecting the body. We first explain a series of theoretical constructs concerning the body, which are essential to understand the impact of self-tracking on our bodies, like body schema, body image, and bodyawareness. Then, we illustrate how individuals’ body image and awareness are affected by the usage of self-tracking technologies in the sports domain. Finally, we point out some lines of future research aimed at providing people with more meaningful representations of their own body, improving their body awareness and even their body image.