What is setting the stage for abdominal obesity reduction? A comparison between personality and health-related social cognitions.

The present longitudinal study examines whether changes in waist circumference are best predicted by relatively stable and broad personality traits (dispositional optimism and pessimism), by modifiable and domain-specific social cognitions (health-related self-efficacy), or a combination of these. Altogether 385 participants (74% women; 50-65 years) attended the GOAL Implementation Trial, a lifestyle counseling intervention to improve diet and physical activity. Measurements were conducted prior to the intervention (Time 1), and 3 months (Time 2) and 12 months (Time 3) after Time 1. Three different models of the potential interplay between dispositional optimism and pessimism and health-related self-efficacy were tested. The analyses showed that the change in health-related self-efficacy during the intervention (Time 1-Time 2) was negatively related with waist circumference change between Time 1 and Time 3, indicating that increases in self-efficacy during the intervention resulted in reduction in waist circumference over 12 months. However, optimism and pessimism were unrelated to waist circumference change either directly or indirectly through changes in self-efficacy. Interventions enhancing participants' positive health-related expectancies such as self-efficacy are likely to be effective even when participants' dispositional expectancies are pessimistic.