This 3D animation from The Human Atlas explains Laparoscopic Gastric Banding.

The digestive process begins in the mouth, where chewing and saliva breakdown food. Digestion continues in the stomach, where food is tuned into a liquid called chyme.

Chyme next passes into the small intestine. Here, enzymes from the pancreas and liver further digest food. It is also in the small intestine where all nutrients and vitamins are absorbed. Small fingerlike projections lining the small intestine, called villi, enable digested food to enter the bloodstream.

Laparoscopic Gastric Banding, or Lap-Band surgery, is one of the more common bariatric procedures because it does not require removal of any part of the digestive tract.

In this procedure, a silicone band is placed around the upper part of the stomach to create a small pouch. The inner surface of the silicone band can be inflated with saline or can be deflated to change the size of the opening. The band is connected by a tube to a reservoir, which is placed under the abdominal skin and fat. After the operation, the surgeon can control the size of the band by injecting saline into the reservoir with a needle.

The lower, larger part of the stomach is still intact below the band. These two parts of the stomach are connected by a small opening. Food passes through the opening, or stoma, from the upper gastric pouch to the lower part more slowly. This delayed emptying gives the patient a sense of fullness, thereby reducing the urge to eat between meals.