ObjectiveAppearance focused self‐concept (i.e., overvaluing the importance of appearance for self‐definition and self‐worth) is theorized to predict dietary restraint and binge eating in the short‐term (e.g., daily life). Yet, no research has examined whether appearance focused self‐concept increases within‐persons during a day and if such increases are linked to greater dietary restraint and binge eating for that day. We addressed this gap in knowledge.MethodSixty‐three female university students completed four items from the Beliefs About Appearance Scale as a measure of appearance focused self‐concept six times per day (9 am, 11 am, 1 pm, 3 pm, 5 pm, and 7 pm) for 14 days. Daily at 9 pm, they completed measures of dietary restraint and binge eating for that day.ResultsAnalyzing data from 555 days, latent growth curve analyses revealed a small‐to‐moderate linear increase in appearance focused self‐concept from 9 am to 3 pm that plateaued from 3 to 7 pm. A more rapid linear increase in appearance focused self‐concept from 9 am to 3 pm was associated with greater binge‐eating frequency during that day, but not with dietary restraint. The findings were observed when adjusting for between‐day appearance focused self‐concept at 9 am, which was positively associated with dietary restraint and binge‐eating frequency.DiscussionFindings are discussed in relation to research on appearance focused self‐concept as a risk factor for disordered eating. Findings are also discussed in relation to how sociocultural factors may increase appearance focused self‐concept over time. Future research should delve into the within‐day dynamic interplay between appearance focused self‐concept and disordered eating.Public significanceOur study revealed a noteworthy increase in the importance women attach to their appearance over the course of a day, correlating with increased binge eating during that day. Additionally, heightened appearance importance at the onset of a day was associated with more dietary restraint and binge eating during that day. These findings suggest a shorter timescale for the connection between appearance importance and disordered eating than previously understood.