Biopsychosocial characteristics of overweight and obese primary care patients: do psychosocial and behavior factors mediate sociodemographic effects?

Background The increasing prevalence of obesity and obesity-related conditions in primary care settings challenges the health care system. Thus, we used available baseline data from an on-going clinical trial to examine the biopsychosocial characteristics of overweight and obese primary care patients. The primary research objective was to ascertain whether theoretically important psychosocial and behavioral variables mediate the empirical relationships between sociodemographic factors and body mass index (BMI). Methods Overweight or obese primary care patients (n = 665) enrolled in an on-going trial of a cognitive-behavioral obesity intervention provided baseline sociodemographic, psychosocial, nutritional, physical activity, and anthropometric data that were analyzed via multiple regression. Results Lower educational attainment was associated with a higher BMI after controlling for decisional balance, social support, self-efficacy, energy intake, and energy expenditure (P < 0.05). In contrast, ethnicity was not associated with BMI after controlling for the psychosocial and behavioral variables. Decisional balance and social support variables were associated with BMI and energy intake, but the directions of some of the associations were not consistent with a priori expectations. Conclusions Overall, we found some evidence of mediation by the psychosocial and behavioral variables of the relationship between ethnicity and BMI, but not for the relationship between education and BMI. In addition, some of the relationships between the psychosocial variables and BMI were opposite of our expectations.