A large number of previous studies have examined the effects of thin-ideal avatars on body image in virtual reality (VR), reporting mixed results. A possible explanation is that individuals' sense of embodiment (SoE) can influence the effects of avatars. Using the body discontinuity paradigm, a paradigm rarely used in prior studies, this study explores how SoE affects users' body image when using thin-ideal avatars in VR. A group of 77 female participants were randomly assigned to one of the SoE conditions to complete a VR task using a thin-ideal avatar. The body image was assessed not only using explicit but also with implicit measures. The result shows that participants in a high SoE condition were more likely to have a more positive actual body image than others in a low SoE condition, regardless of whether implicit or explicit measures were used. Furthermore, the ownership subcomponent of the SoE significantly mediated the relationship between thin-ideal avatars exposure and the actual body image using implicit measures. However, no substantial difference in ideal body image was found. These findings extend our understanding of avatar effects in VR, thereby providing additional evidence for using avatars to explore body image-related phenomena and to use them in psychotherapeutic applications such as treatments for eating disorders.