Abstract: Documenting weight-related journeys (e.g., weight loss, weight gain) is prevalent on social media, as is weight stigma, resulting in easily accessible personal archives filled with emotional, and potentially stigmatizing content. Through semi-structured interviews with 17 U.S.-based social media users sharing weight-related journeys, we investigate the motivations for and impacts of returning to previously posted weight-related social media content. We show how these personal archives foster a contested relationship between one's past and current self, where returning to past content facilitates dynamic interpretations of the self. We argue these interpretations' impacts cannot be understood without acknowledging and addressing the socio-technical context in which they exist: one filled with weight stigma, fatphobia, and narrow body ideals. We introduce the novel concepts of Transtemporal Support and Transtemporal Harm to describe the support and harms that one experiences in the present from returning to their past social media content. We posit that designs accounting for transtemporal support 1) can facilitate reflective sense-making for users who create repositories of digital artifacts about sensitive, potentially stigmatizing experiences on social media, and 2) should not perpetuate transtemporal harm.