Longitudinal studies on FFM personality traits and weight have been relatively sparse. To date, the only longitudinal study that assessed all the FFM domains and change in BMI over a significant period of time found that participants low on Conscientiousness increased in BMI across 14 years of middle adulthood (Brummett et al., 2006). In a three-year prospective study, Terracciano and colleagues (Terracciano et al., 2009) found virtually the same pattern of associations between personality and weight in concurrent and prospective analyses. During the three-year follow-up, however, there was little change in BMI. Long-term longitudinal studies that have multiple assessments of adiposity across the lifespan are needed to identify how personality is associated with the trajectory of BMI. In addition, to date, the one longitudinal study on personality and BMI change only assessed domain-level traits. Facet-level analyses provide a richer understanding of the relation between personality traits, behaviors and life outcomes (e.g., Paunonen, Haddock, Forsterling, & Keinonen, 2003).
