Obesity is one of the commonest chronic metabolic diseases worldwide, and is often associated with comorbidities. The common clinical characteristics of the co-morbidities of obesity are described, including diabetes mellitus, hypertension, obstructive sleep apnea/ hypopnea syndrome, non-alcoholic fatty liver disease, obesity-related glomerulopathy, polycystic ovary syndrome, depressive disorders, and obesity-associated neoplasia. The aim is that obesityrelated diseases should be recognized at an early stage by medical professionals, so that they can be diagnosed and treated early in their progression.