Obesity is becoming a significant problem in the United States. From 1960 to 2000 the rate of obesity more than doubled from 12.8% to 30%. Obesity is defined as a body mass index greater than 30. This index is calculated by applying a formula to a person’s height and weight. The chances of having a knee replacement are 8 times higher for patients with a body mass index or BMI of 30 or greater and 18 times higher for patients with a BMI of 35 or more. The morbidly obese, those with a BMI over 40, have higher complication rates, higher risk of infection, and premature loosening and failure of the implant. Obese patients often say they will loose weight after they have their joint replacement, though most studies show that does not typically happen. In one study, patients gained an average of three pounds one year after their joint replacement surgery. Surgical outcomes can markedly improve if a patient loses weight prior to surgery, according to several studies. As we proceed down a path to health care reform it is important for all of us insurers, physicians, and patients to take responsibility to do what we can do to lower the cost of health care and improve outcomes.