We likewise used HLM to test whether adiposity was associated with change in personality across the adult lifespan. Similar to BMI, we fit a quadratic model for personality at Level 1 because of nonlinear changes in personality across adulthood (Terracciano, McCrae, Brant, & Costa, 2005), and tested sex, ethnicity, education, and the first BMI assessment as Level 2 predictors of the linear slope. Again, to account for secular trends, we also included the year of each participant’s first personality assessment, centered on the grand mean (1995).
