Current financing for research in obesity surgery is virtually nonexistent, despite the magnitude of this disease as a public health problem.

Dr. Mason also developed the original gastric bypass for weight reduction in 1966 and is known for his pioneering work as the "father of obesity surgery".

Dr. Fobi says the risk of death in his experience - nearly 20 years of obesity surgery and thousands of operations - is 1 in 500.

It is also common in persons whose bodies do not absorb food properly (malabsorption), such as sometimes occurs after obesity surgery.

There are two main types of obesity surgery.

Rapid weight loss after obesity surgery can contribute to the development of gallstones as well by increasing the lithogenicity of bile.

In a report last month, the agency said that 40 percent of patients who have obesity surgery develop complications within six months.

Federal researchers found that complications from obesity surgery significantly increased costs.

Over all, said William E. Encinosa, an economist at the health research agency, medical spending averaged $29,921 for obesity surgery and six months of follow-up care.

It has been reported to occur in up to 20% of patients who had jejunoileal bypass surgery, a form of obesity surgery that is rarely performed today.