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Facts About Weight Loss Surgery

For severely obese people for whom diet and exercise have failed, weight loss surgery can literally be lifesaving. It's estimated roughly 220,000 people underwent weight loss surgery last year in the U.S.

Depending on the type of weight loss surgery, patients often lose 30% to 50% of their extra weight six months after surgery. Yet weight loss surgery is major surgery and does come with small but serious risks. Read on to get familiar with the types of weight loss surgery available and how they work.

How Weight Loss Surgery Works

Weight loss surgery works in two ways: by restriction and malabsorption.


This kind of weight loss surgery works by preventing the stomach from stretching to full size. Normally, the stomach can hold six cups of food. After weight loss surgery, the stomach can hold only a cup or so. This results in feeling full faster, eating less, and losing weight.


Some weight loss surgeries also divert food around a section of intestine. By skipping an area of intestine fewer calories are absorbed. Lower calorie absorption leads to weight loss.

Most weight loss surgery today is laparoscopic. In laparoscopic surgery, five to six 1-inch-long incisions are made in the belly wall. The surgeon inserts tools and a camera through these holes then operates while watching a video screen.

In open surgery (laparotomy), the surgeon makes a large incision along the middle of the belly. This is sometimes necessary, when the surgery cannot be done laparoscopically.

Types of Weight Loss Surgery

Roux-en-Y Gastric Bypass Surgery

This is the most common weight loss surgery performed today, making up about 80% of all weight loss surgery in the U.S.

There are two parts to a roux-en-Y gastric bypass:

  1. The surgeon divides the stomach into a large portion and a much smaller portion. The small stomach portion is then stapled into a small pouch.
  2. The stomach pouch is disconnected from the first part of the small intestine (the duodenum). The surgeon reconnects the stomach to the second part of the small intestine (the jejunum).

After gastric bypass, a smaller amount of food makes a person feel full. He or she eats less and loses weight. Food also bypasses a small part of intestine, which reduces absorption of calories.

Laparoscopic Adjustable Gastric Banding

This is the second most common weight loss surgery. The gastric banding procedure involves the following:

  • Using laparoscopic tools, the surgeon places an inflatable silicone band around the upper stomach.
  • The band is tightened so the stomach becomes a small pouch with a narrow outlet.
  • Afterwards, the patient feels full faster, eats less, and loses weight.
  • The band can be tightened or loosened, to minimize side effects and improve weight loss.

Gastric banding is considered the least invasive weight loss surgery and the procedure can be reversed if necessary.

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