Overweight people have a body mass index between 25 and 30 and obese people have a body mass index between 30 and 40. Morbidly obese people have a body mass index greater than 40. Morbid obesity is usually associated with significant medical problems which include hypertension, diabetes, heart disease, stroke, sleep apnoea, arthritis and sudden death. Life expectancy becomes increasingly diminished as the body mass index rises, so that a person with a body mass index of 40 has approximately twice the chance of premature death of a person with a normal body mass index. Morbid obesity is also associated with significant physical and social limitations.
Depression is common.
The conservative treatment of morbid obesity by dieting and exercise programs is notoriously unrewarding. Most people who are obese will have tried many diets and weight reduction programs. They usually produce only very limited and transient weight loss. In fact, most people who have tried dieting regain the lost weight and more. The failure of diet programs led to the hope that a surgical procedure would be able to achieve lasting weight loss.