Five- to ten-million people in the United States are morbidly obese-defined as100 pounds or more overweight or having a Body Mass Index (BMI) of 40 or greater. Ninety-five percent of morbidly obese people who lose weight through traditional medically managed programs ultimately regain it.

People who are obese have higher rates of medical problems. If a person suffers from mild obesity then diet and exercise are usually the proper treatment. Once a person reaches the level of morbid obesity, the weight causes quicker and more extensive damage to the body. These factors translate into a greater need for weight loss, supporting the rationale for more extreme measures such as surgery to control weight.

The medical complications of obesity may occur in moderately obese people, but the frequency of these associated problems (such as heart disease, high blood pressure, diabetes, premature death, etc.) increases dramatically as weight increases. For example, very obese men between the ages of 25-35 have a 12 fold greater risk of dying prematurely compared to their normal weight counterparts.