Purpose <p>This study examined what is associated with self-objectification, body uneasiness, body investment, and depersonalization in adults who altered their bodies. We tested adults involved in body modification (BM) or plastic surgery (PS), and we compared them to controls to clarify these associations.</p> Methods <p>We conducted an observational cross-sectional study of 235 adults (72.8% female) and grouped them into three categories: BM (<i>n</i> = 63), PS (<i>n</i> = 48), and controls (<i>n</i> = 124). Participants completed the Objectified Body Consciousness Scale, the Body Investment Scale, and the Body Uneasiness Test. We used analysis of covariance to compare groups while controlling for age and gender. We tested mediation by Body Investment Scale subscales and moderation by the number of BM and PS interventions in the relationship between self-objectification and depersonalization.</p> Results <p>PS showed the highest self-objectification and body uneasiness, BM was intermediate, and controls were lowest. Body investment, particularly the body image subscale, mediated the association between self-objectification and depersonalization. The number of BM interventions strengthened the association between body investment and depersonalization, and PS tended to moderate the direct link between self-objectification and depersonalization.</p> Conclusion <p>These findings suggest that body investment partly explains the connection between self-objectification and depersonalization, and that BM and PS relate differently to depersonalization in nonclinical adults. Given the cross-sectional design, we can only draw associative (not causal) conclusions.</p> <p>Level of Evidence: III, observational cross-sectional study.</p>