There are two primary approaches to surgical weight loss: restriction alone and restriction with malabsorption (a reduction of the body's ability to absorb calories and nutrients) via gastric bypass.
Gastric bypass treatments typically generate more weight loss than restriction treatments, which only decrease food intake. People who undergo gastric bypass generally lose at least two-thirds of their excess weight within two years.
Restrictive procedures, which are more common than gastric bypass surgeries, restrict food intake but do not interfere with the normal digestive process.
These procedures restrict food intake by creating a small pouch at the top of the stomach where the food enters from the esophagus. The pouch initially holds about one ounce of food, an amount that expands to six to eight ounces with time. The pouch's lower outlet usually has a diameter of about 1/4 inch. The small outlet delays the emptying of food from the pouch and causes a feeling of fullness.
After the operation, you can typically eat only 1/2 to 1 cup of food without discomfort or nausea. You will likely lose the ability to eat large amounts of food in one sitting and you must thoroughly chew your food. Ideally, you will progress to eating modest amounts of food without feeling hungry.
About 80 percent of people who have a restrictive procedure lose weight. About 30 percent of those undergoing vertical banded gastroplasty achieve normal healthy weight. However, some individuals are unable to adjust their eating habits and fail to lose the desired weight while others regain weight. As with all weight loss procedures, successful results depend on your lifestyle choices and commitment.
Gastric Banding or Laparoscopic Placement of a Lap Band
In this procedure, a band made of special material is placed around the stomach near its upper end, creating a small pouch and a narrow passage into the larger remainder of the stomach. This band is usually placed via a laparoscope, a fiber-optic tube and light source through which some surgical instruments may pass.
Vertical Sleeve Gastrectomy
The surgeon performing this procedure transforms the stomach into a gastric tube with a limited volume capacity. The term sleeve gastrectomy refers to the technique used to remove the stomach. This is achieved by doing a sleeve resection (surgical removal), and the removed portion of the stomach looks like a sleeve. Technically, 90 percent of the stomach is removed via laparoscopy.
- Vomiting – If food is not well chewed, the small stomach is over-stretched, which leads to vomiting.
- Erosion of the band
- Breakdown of the staple line
- Leakage of stomach juices into abdomen, which requires emergency surgery
- Death rate: negligible
Restrictive procedures lead to weight loss in most cases. However, some people are unable to adjust their eating habits and fail to lose the desired weight. Weight loss ranges from 30 to 100 percent of excess weight. Some patients, unfortunately, regain weight.
Restrictive and Malabsorptive Procedures
These procedures accomplish two things to encourage weight loss. First, a small stomach pouch is created to restrict food intake. Additionally, a bypass of the duodenum and other segments of the small intestine is constructed to cause malabsorption.
Roux-en-Y Gastric Bypass
This operation is the most common gastric bypass and weight loss procedure performed in the U.S. It can be done as a minimally invasive procedure or as a traditional, open surgery.
First, a small stomach pouch is created with stapling or vertical banding. This causes restriction of food intake. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the duodenum (first segment of the small intestine) as well as the first portion of the jejunum (second segment of the small intestine). This results in reduced calorie and nutrient absorption.
Extensive Gastric Bypass (Biliopancreatic Diversion with Duodenal Switch)
In this more complicated gastric bypass operation, portions of the stomach are removed. The small pouch that remains is connected directly to the final segment of the small intestine, thus completely bypassing both the duodenum and jejunum. Although this procedure successfully promotes weight loss, it is not widely used because of the high risk of nutritional deficiencies.
- Pouch stretching
- Breakdown of staple lines
- Leakage of stomach contents into the abdomen
- Nutritional deficiencies