Emotions are expressed by the face, the voice and the whole body. Research on the face and the voice has not only demonstrated that emotions are perceived categorically, but that this perception can be manipulated. The purpose of this study was to investigate, via two separate experiments using adaptation and multisensory techniques, whether the perception of body emotion expressions also shows categorical effects and plasticity. We used an approach developed for studies investigating both face and voice emotion perception and created novel morphed affective body stimuli, which varied in small incremental steps between emotions. Participants were instructed to perform an emotion categorisation of these morphed bodies after adaptation to bodies conveying different expressions (Experiment 1), or while simultaneously hearing affective voices (Experiment 2). We show that not only is body expression perceived categorically, but that both adaptation to affective body expressions and concurrent presentation of vocal affective information can shift the categorical boundary between body expressions, specifically for the angry body expressions. Overall, our findings provide significant new insights into emotional body categorisation, which may prove important in gaining a deeper understanding of body expression perception in everyday social situations.