Comorbidities of overweight and obesity: current evidence and research issues

Purpose: The evidence with regard to the relationship of obesity with medic al comorbidities was assessed and priority research issues identified. Meth ods: The existing literature in English was surveyed. Results: The evidence is overwhelming on the association of obesity to a number of medical condi tions. These include: insulin resistance, glucose intolerance, diabetes mel litus, hypertension, dyslipidemia, sleep apnea, arthritis, hyperuricemia, g all bladder disease, and certain types of cancer. The independent associati on of obesity seems also clearly established for coronary artery disease, h eart failure, cardiac arrhythmia, stroke, and menstrual irregularities. The relationship between central (or upper body) obesity and the above conditi ons is positive for most of them but with a lesser number of studies. Most of the fat distribution studies have been done using anthropometric measure ments rather than the more accurate magnetic resonance imaging or computer tomographic scans. Priority research issues include the following: more def initive data on the relation of central fat to comorbidities; the proportio nal importance of subcutaneous versus visceral fat in producing comorbiditi es; the relationship between obesity and psychiatric disease; the genetics of the relationship between obesity and each of the comorbidities; the inde pendent contribution of dirt and of sedentariness to the development of eac h of the comorbidities; the impact of gender, race, intensity, and duration on these associations. Conclusions: The evidence for the relationship of o besity to a number of comorbidities is strong, though the strength of the r elationship varies with the condition, Much more research is necessary on c ausation and on what other factors may play an interactive role.