Depression, physical activity, and BMI: Findings from the National Health and Nutrition Examination Survey 2005-2006

BACKGROUND: Evidence suggests depression is an incapacitating, but treatable condition associated with impaired cognitive and physical functioning and decreased quality of life. Obese persons are more likely to suffer from depression than their normal weight peers. Regular physical activity (PA) can reduce depressive symptoms. However, the potential protective effect of PA on the relationship between depression and BMI (kg/m²) remains unclear.

PURPOSE: To examine the prevalence of depression by BMI weight status category and to determine the association between PA, BMI, and depression.

METHODS: The National Health and Nutrition Examination Survey (NHANES) 2005-2006 were used for analysis (n=4678, 52% female). Participants (aged ≥20) who scored ≥10 on the Patient Health Questionnaire were categorized as depressed. BMI was determined from measured height and weight, and PA from self-report. Multivariate regression models estimated adjusted ORs, controlling for age, gender, race/ethnicity, and education. Bonferroni adjustments were made because of multiple comparisons.

RESULTS: Multivariate models that included PA resulted in no difference in depression score for those with BMI 25-29.9 kg/m² (overweight category; OR= 0.81, 95% CI: 0.5-1.2) or ≥30 kg/m² (obese category; OR= 1.1, 95% CI: 0.7-1.8). However, individuals with regular PA were 60% less likely to be depressed than those who did not engage in regular moderate or vigorous PA (95% CI: 0.3-0.6), after controlling for BMI status.

CONCLUSIONS: Participation in regular moderate or vigorous PA appears to be associated with lower rates of depression, regardless of BMI.