I'm not too clear on how to interpret hierarchical model coefficients, but they do give at least one description of effect size, on pg6:

These associations revealed clinically meaningful differences in weight. For example, participants who scored in the top 10% of Neuroticism's Impulsiveness weighed, on average, over 11 Kg more than those who scored in the lowest 10% of this trait. Likewise, participants who scored high on Conscientiousness's Order weighed about 4.5 Kg less than those who scored low on Order.

and pg8:

In addition, the emotional aspects of impulsivity (N5: Impulsiveness and E5: Excitement-Seeking) were also associated with greater increases in adiposity. For example, on average, at age 30, those who scored one standard deviation above the mean on impulsivity had a BMI that was approximately 2.30 points higher than those who scored one standard deviation below the mean on this trait. By age 90, this gap increased to a 5.22 BMI point difference (see Figure 3).