Nutrition Support for the Obese Surgical Patient

Jay M. Mirtallo, MS, RPh


January 14, 2008

In This Article


Obesity is commonly observed in clinical practice; in fact, it is estimated that up to two thirds of the US population is overweight or obese. Diseases associated with obesity often require hospitalization and surgery, and complications are more frequent in the obese patient, often leading to a need for nutrition support.

The metabolic disorders associated with obesity present challenges to providing nutrition support, specifically as it relates to the safe and efficacious dosing of calories and protein. If not dosed properly, complications such as hyperglycemia may influence outcomes of surgical procedures. The purpose of this review is to provide an overview of nutrition support in the obese surgical patient, and to discuss specific issues that should be addressed by the clinician responsible for feeding the patient in cases where enteral or parenteral nutrition are required.

Definition and Classification of Obesity

Obesity is defined as the accumulation of excess weight, predominantly as fat. This excess body fat is associated with multiple organ-specific consequences and diseases ( Table 1 )[1] that lead to an increased risk of mortality, multiple diseases, diminished quality of life, and complications of acute illness.[2]

Simply put, obesity is the level of excess weight associated with medical consequences, and "morbid obesity" is the level at which morbidity and mortality are significantly increased. The term "morbid obesity" was adapted by the surgical community to identify those patients who were candidates for weight-reduction surgery. Obesity has also been associated with an increased risk of postoperative complications.[3]

Initially, the definition of morbid obesity was based on a level above the "ideal" body weight (IBW), such as 100 pounds over IBW or greater than 200% IBW.[4] Problems with the use of IBW,[5] however, have led to the current use of body mass index (BMI), which represents the patient's weight as it relates to his or her height. BMI is the weight in kilograms divided by the height in meters squared. Classifications for overweight and obesity are provided in Table 2 .[2,4] Whereas the identification of an obese patient for nutrition support purposes used to be based on a weight in excess of ideal (120% or 130% of IBW), identification using the BMI classification is the currently accepted method.


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