Morbid obesity

Morbid obesity is a global health problem which carries substantial morbidity and mortality.  Obesity is defined as a body weight exceeding ideal body weight (IBW) by 20%, or a body mass index (BMI) of 30 to 35 kg/m².  Morbidly obese individuals generally exceed IBW by 100 pounds or more, or are 100% over IBW. 

In 1991, the National Institutes of Health defined morbid obesity as a BMI of 35 kg/m² or greater with severe obesity-related co-morbidity or BMI of 40 kg/m² or greater without co-morbidity [1]. Superobesity is defined as a body weight exceeding IBW by 225% or more, or a BMI of 50 kg/m² or greater.

Central obesity is associated with metabolic syndrome, which is a cluster of consists of HTN, insulin resistance, hypertriglyceridemia, hepatic steatosis, and an elevated risk of DM, CAD, and CVA.

The android body habitus (see the "apple" in the figure) carries a higher operative risk than the gynecoid pattern; because of the large amount of intra-abdominal fat, there is a paucity of intraabdominal space and enlargement of the liver. With the gynecoid (pear-shaped) pattern of obesity, adipose tissue is distributed more in the hips and thighs.

The laparoscopic adjustable gastric band is a restrictive procedure which involves placement of a silicone band around the proximal stomach. An inflatable balloon controls the diameter of the band by means of a port that is placed in the anterior abdominal wall. It is an example of a restrictive procedure, and restricts the passage of food (but not liquids). Excess weight loss (EWL) is about 40-50% at 3 yrs followup. Complications include gastric prolapse, band erosion, and esophageal dilatation. While weight loss is not as rapid as with the GBP, the band's adjustability and low morbidity and mortaility make it appealing for some patients.

The duodenal switch is a malabsorptive procedure. It combines an intestinal bypass with a sleeve gastrectomy, in which the excluded stomach is resected to create a long gastric tube. The duodenum is transected. The ileum is transected approximately 300 cm proximal to the ileocecal valve. The distal end is anastomosed to the duodenal cuff and the proximal end is anastomosed 100 cm proximal to ileocecal valve. EWL is about 70% long-term. Complications include protein-calorie malnutrition, steatorrhea, and fat-soluble vitamin deficiencies, which can lead to osteoporosis and night blindness.

The gastric bypass combines restrictive and malabsorptive features. A 15 mL pouch is created. The jejunum is divided about 40-50 cm distal to the ligament of Treitz. The distal end is anastomosed to the pouch and the proximal end is anastomosed 75-150 cm distally to create the Roux limb. EWL is about 50-60% long term. Complications include leak, venous thromboembolism, obstruction, stomal stenosis, marginal ulcer, and vitamin deficiencies.

1. National Institutes of Health Consensus Development Panel: Gastrointestinal Surgery for Severe Obesity.  Am J Clin Nutr 1992;55:615S-9S.