• Depression;
  • exercise;
  • obesity;
  • health behaviors


What is already known about this subject

  • Depressive symptoms and obesity are highly prevalent in primary care settings.
  • Depressive symptoms and obesity are positively related; as body weight increases, individuals are more likely to display depressive symptoms.

What this study adds

  • This study examines the moderating roles of health behaviours (alcohol use, smoking status and vigorous exercise) on the relationship between body mass index and depressive symptoms.
  • Exercise attenuates the relationship between depressive symptoms and obesity.

Primary care patients often report multiple health risk behaviours and symptoms, including obesity and depressive symptomatology. This study examined the relationship between body mass index (BMI) and depressive symptomatology among primary care patients and tested its moderation by health behaviours. Primary care patients (n = 497) completed self-report questionnaires. Using three multilevel models, we tested the moderation of health behaviours on the BMI-depressive symptoms relationship. After controlling for relevant covariates, BMI was positively related to depressive symptoms. Smokers reported more depressive symptoms (P < 0.01), whereas vigorous exercisers reported fewer (P < 0.001). Alcohol consumption was not related to depressive symptoms (P > 0.05). Only vigorous exercise significantly moderated the BMI-depression relationship (P < 0.05). BMI is positively related to depressive symptoms among patients who do not participate in vigorous activity, suggesting that vigorous activity reduces the risk for depressive symptoms among patients with higher BMI.