Associations between class III obesity, high waist circumference and depression: Results from NHANES 2005-2006

Background and Significance: Although the affects of obesity on physical health have been well documented, the consequences for mental health are less certain. Objectives: (1) To investigate the association between obesity and depression in a representative sample of American adults, (2) to investigate gender and severity of obesity as modifiers of the association between depression and body mass index (BMI), (3) to determine if waist circumference (WC) is associated with depression, (4) to explore whether specific health behaviors or poor physical health are possible mediators of the obesity depression association. Methods: Logistic regression models were run using data from the National Health and Nutrition Examination Survey, 2005-2006 to investigate associations of BMI and WC with current depression as measured by the Patient Health Questionnaire. Results: In unadjusted analyses high WC (>88 cm in women and >102 cm in men), and severe obesity (BMI =>40) were associated with higher prevalence of depression in women only. Among the overweight (BMI =>25 and <30), high WC was associated with depression (odd ratio (OR) = 2.20, 95% confidence interval (CI): 1.10, 4.39). These associations weakened and lost statistical significance after adjusting for self-rated health and number of chronic conditions. Conclusion: These findings are supportive of an association between depression and obesity in women who are severely obese. They are also suggestive of an association between central abdominal fat and depression, even in those who are not obese. Poor physical health should be investigated further as a possible mediator of the obesity depression association.