Obesity: differential diagnosis

This topic addresses the causes and consequences of obesity, defined as a body mass index (BMI) of 30 or above. While BMI is the most commonly used measure of obesity, the waist-to-height ratio correlates better with visceral obesity. At least 1.1 billion adults are overweight worldwide, but a medical cause for obesity is found in less than 1 out of every 100 cases. The health consequences of obesity are diverse and serious. Approximately 50% of all hypertension is secondary to obesity, and the heart may also be harmed by obesity-induced chronic volume overload and ischaemic heart disease. Obesity contributes strongly to the pathophysiology of type II diabetes and its consequences. Obese patients have higher rates of stroke, osteoarthritis, obstructive sleep apnoea, gastro-oesophageal reflux, chronic liver disease, and infertility. In addition, obesity increases the incidence of some cancers (e.g. breast, prostate, and colorectal). The psychological and social effects of obesity include higher rates of depression and anxiety, and reduced employment.