A seemingly more optimal nutritional indicator is body mass index (BMI) (body weight in kilograms divided by the square of the height in meters). This index aims to overcome the limitations of changes in body weight and the need to compare it with expected normal values. The data to support the use of BMI are solid. In any scenario, a BMI of less than 15 kg/m2 is associated with a significant increase in morbidity.18,21 In hospitalized patients, a BMI less than 18.5 kg/m2 is associated with a longer stay in the intensive care unit, increased frequency in postoperative complications, higher readmission rates, and delays in resumption of oral intake.22 The use of BMI as a measure of nutritional assessment is limited by poor sensitivity with respect to baseline assessment, particularly for overweight patients. First, individuals in the high-normal range can undergo significant change in nutritional status prior to estimation of having an abnormal status or being nutritionally deplete. Furthermore, in our practice, based on a BMI of 25.0 to 29.9 kg/m2, we consider nearly 30% of the US population is overweight, with another 30% categorized as obese (BMI >30 kg/m2). This elevated BMI has documented links to heart disease, diabetes, hypertension, and increased morbidity with major operations. Is the increased incidence of perioperative morbidity in patients with elevated BMIs all related to comorbid illness or is it that these patients are truly malnourished? Furthermore, comorbid illness that promotes underhydration, edema, or ascites (ie, renal failure, liver disease, or malignancy) confounds this calculation. However, BMI is a useful tool, particularly for the subset of surgical patients in the lower range, who traditionally have needed and benefited from nutrition intervention.