Depressed persons have a higher risk of developing somatic conditions such as cardiovascular disease, diabetes and obesity. Somatic comorbidity in depressed persons may be explained by mediating mechanisms such as unhealthy lifestyle and unfavorable pathophysiological disturbances. There are alternative explanations for somatic comorbidity in depressed persons: genetic pleiotropy, iatrogenic effects, and the phenomenon 'somatic depression'. In the latter, the symptoms of depression are a consequence of clinical or subclinical somatic conditions. When treating a depressed patient, their somatic health should also be monitored. Further research is needed to examine whether specific interventions may prevent somatic comorbidity in depression.