The mortality rate for bariatric operations ranges from 0.2 to 1.8 percent. This relates to the patient's risk for complications. Surgery on obese individuals is inherently high-risk. Many of the complications that cause postoperative death are not related specifically to bariatric surgery; rather, they are a function of obesity. For example, one of the most common causes of postoperative death is pulmonary embolus - a blood clot in the lung. These can occur in obese patients from any type of surgery they have.

The risks vary with the patient. Very large older men have a much higher risk of complications than relatively healthy, smaller women.

Although 1 in 200 or 0.5 percent seems high, death rates of 5 percent following heart operations are not unusual.